| 1. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Hu, Jutao, et al.
(författare)
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The origin of anomalous hydrogen occupation in high entropy alloys
- 2022
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 10:13, s. 7228-7237
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Tidskriftsartikel (refereegranskat)abstract
- Metal hydrogen storage materials have been the focus of intensive research in the field of hydrogen-based economy. An outstanding question is that the number of hydrogen atoms accommodated in metal hydrides is generally much below the number of interstices, which limits their hydrogen storage capacities. Unlike traditional FCC metal hydrides where hydrogen can only occupy tetrahedral interstices, this study demonstrates that hydrogen can also occupy octahedral interstices in FCC high entropy alloy (HEA) hydrides, which leads to the violation of the Switendick criterion. For Ti25V25Nb25Ta25 and Ti25V25Nb25Zr25 HEAs, nearly 20% and 17.5% of octahedral interstices can be occupied by hydrogen, respectively. The anomalous hydrogen occupation mainly originates from the intrinsic electron delocalization between hydrogen atoms in HEA hydrides, which presents a sharp contrast to traditional metal hydrides. Such electron delocalization decreases repulsive interactions between hydrogens and promotes the electron localization at octahedral interstices. Additionally, this study reveals that hydrogen occupation at octahedral interstices enhances the structural disordering and decreases the thermal stability of HEA hydrides, which will be beneficial to reduce the dehydrogenation temperature. The presented results may provide a new strategy for the design of high-density storage materials.
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| 3. |
- Li, Xiane, et al.
(författare)
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Mapping the energy level alignment at donor/acceptor interfaces in non-fullerene organic solar cells
- 2022
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Ingår i: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Energy level alignment (ELA) at donor-acceptor heterojunctions is of vital importance yet largely undetermined in organic solar cells. Here, authors determine the heterojunction ELA with (mono) layer-by-layer precision to understand the co-existence of efficient charge. Energy level alignment (ELA) at donor (D) -acceptor (A) heterojunctions is essential for understanding the charge generation and recombination process in organic photovoltaic devices. However, the ELA at the D-A interfaces is largely underdetermined, resulting in debates on the fundamental operating mechanisms of high-efficiency non-fullerene organic solar cells. Here, we systematically investigate ELA and its depth-dependent variation of a range of donor/non-fullerene-acceptor interfaces by fabricating and characterizing D-A quasi bilayers and planar bilayers. In contrast to previous assumptions, we observe significant vacuum level (VL) shifts existing at the D-A interfaces, which are demonstrated to be abrupt, extending over only 1-2 layers at the heterojunctions, and are attributed to interface dipoles induced by D-A electrostatic potential differences. The VL shifts result in reduced interfacial energetic offsets and increased charge transfer (CT) state energies which reconcile the conflicting observations of large energy level offsets inferred from neat films and large CT energies of donor - non-fullerene-acceptor systems.
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| 4. |
- Qian, Deping, et al.
(författare)
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Correlating the Hybridization of Local-Exciton and Charge-Transfer States with Charge Generation in Organic Solar Cells
- 2023
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Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- In organic solar cells with very small energetic-offset (& UDelta;ELE - CT), the charge-transfer (CT) and local-exciton (LE) states strongly interact via electronic hybridization and thermal population effects, suppressing the non-radiative recombination. Here, we investigated the impact of these effects on charge generation and recombination. In the blends of PTO2:C8IC and PTO2:Y6 with very small, ultra-fast CT state formation was observed, and assigned to direct photoexcitation resulting from strong hybridization of the LE and CT states (i.e., LE-CT intermixed states). These states in turn accelerate the recombination of both CT and charge separated (CS) states. Moreover, they can be significantly weakened by an external-electric field, which enhanced the yield of CT and CS states but attenuated the emission of the device. This study highlights that excessive LE-CT hybridization due to very low , whilst enabling direct and ultrafast charge transfer and increasing the proportion of radiative versus non-radiative recombination rates, comes at the expense of accelerating recombination losses competing with exciton-to-charge conversion process, resulting in a loss of photocurrent generation.
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| 5. |
- Sun, Huiliang, et al.
(författare)
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Reducing energy loss via tuning energy levels of polymer acceptors for efficient all-polymer solar cells
- 2020
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Ingår i: Science China Chemistry. - : Springer Science and Business Media LLC. - 1869-1870 .- 1674-7291. ; 63:12, s. 1785-1792
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Tidskriftsartikel (refereegranskat)abstract
- The open-circuit voltage (Voc) of all-polymer solar cells (all-PSCs) is typically lower than 0.9 V even for the most efficient ones. Large energy loss is the main reason for limiting Voc and efficiency of all-PSCs. Herein, through materials design using electron deficient building blocks based on bithiophene imides, the lowest unoccupied molecular orbital (LUMO) energy levels of polymer acceptors can be effectively tuned, which resulted in a reduced energy loss induced by charge generation and recombination loss due to the suppressed charge-transfer (CT) state absorption. Despite a negligible driving force, all-PSC based on the polymer donor and acceptor combination with well-aligned energy levels exhibited efficient charge transfer and achieved an external quantum efficiency over 10% while maintaining a large Voc of 1.02 V, leading to a 9.21% efficiency. Through various spectroscopy approaches, this work sheds light on the mechanism of energy loss in all-PSCs, which paves an avenue to achieving efficient all-PSCs with large Voc and drives the further development of all-PSCs.
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| 6. |
- Sun, Huiliang, et al.
(författare)
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Reducing energy lossviatuning energy levels of polymer acceptors for efficient all-polymer solar cells
- 2020
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Ingår i: Science China Chemistry. - : Science China Press and Springer-Verlag GmbH Germany. - 1674-7291 .- 1869-1870. ; 63, s. 1785-1792
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Tidskriftsartikel (refereegranskat)abstract
- The open-circuit voltage (V-oc) of all-polymer solar cells (all-PSCs) is typically lower than 0.9 V even for the most efficient ones. Large energy loss is the main reason for limitingV(oc)and efficiency of all-PSCs. Herein, through materials design using electron deficient building blocks based on bithiophene imides, the lowest unoccupied molecular orbital (LUMO) energy levels of polymer acceptors can be effectively tuned, which resulted in a reduced energy loss induced by charge generation and recombination loss due to the suppressed charge-transfer (CT) state absorption. Despite a negligible driving force, all-PSC based on the polymer donor and acceptor combination with well-aligned energy levels exhibited efficient charge transfer and achieved an external quantum efficiency over 10% while maintaining a largeV(oc)of 1.02 V, leading to a 9.21% efficiency. Through various spectroscopy approaches, this work sheds light on the mechanism of energy loss in all-PSCs, which paves an avenue to achieving efficient all-PSCs with largeV(oc)and drives the further development of all-PSCs.
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| 7. |
- Hertzberg, Joachim, et al.
(författare)
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The RACE Project : Robustness by Autonomous Competence Enhancement
- 2014
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Ingår i: Künstliche Intelligenz. - : Springer Berlin/Heidelberg. - 0933-1875 .- 1610-1987. ; 28:4, s. 297-304
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the aims, the approach, and the results of the European project RACE. The project aim was to enhance the behavior of an autonomous robot by having the robot learn from conceptualized experiences of previous performance, based on initial models of the domain and its own actions in it. This paper introduces the general system architecture; it then sketches some results in detail regarding hybrid reasoning and planning used in RACE, and instances of learning from the experiences of real robot task execution. Enhancement of robot competence is operationalized in terms of performance quality and description length of the robot instructions, and such enhancement is shown to result from the RACE system.
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| 8. |
- Jiang, Kui, et al.
(författare)
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Suppressed recombination loss in organic photovoltaics adopting a planar-mixed heterojunction architecture
- 2022
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Ingår i: Nature Energy. - : NATURE PORTFOLIO. - 2058-7546. ; 7:11, s. 1076-1086
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Tidskriftsartikel (refereegranskat)abstract
- At present, high-performance organic photovoltaics mostly adopt a bulk-heterojunction architecture, in which exciton dissociation is facilitated by charge-transfer states formed at numerous donor-acceptor (D-A) heterojunctions. However, the spin character of charge-transfer states originated from recombination of photocarriers allows relaxation to the lowest-energy triplet exciton (T-1) at these heterojunctions, causing photocurrent loss. Here we find that this loss pathway can be alleviated in sequentially processed planar-mixed heterojunction (PMHJ) devices, employing donor and acceptor with intrinsically weaker exciton binding strengths. The reduced D-A intermixing in PMHJ alleviates non-geminate recombination at D-A contacts, limiting the chance of relaxation, thus suppressing T-1 formation without sacrificing exciton dissociation efficiency. This resulted in devices with high power conversion efficiencies of >19%. We elucidate the working mechanisms for PMHJs and discuss the implications for material design, device engineering and photophysics, thus providing a comprehensive grounding for future organic photovoltaics to reach their full promise. Organic solar cells with a bulk-heterojunction architecture suffer from photocurrent loss driven by triplet states. Now, Jiang et al. show that sequentially deposited donor-acceptor planar-mixed heterojunctions suppress triplet formation, enabling efficiencies over 19%.
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| 9. |
- Liu, Tao, et al.
(författare)
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16% efficiency all-polymer organic solar cells enabled by a finely tuned morphology via the design of ternary blend
- 2021
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Ingår i: Joule. - : CELL PRESS. - 2542-4351. ; 5:4, s. 914-930
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Tidskriftsartikel (refereegranskat)abstract
- A SUMMARY There is an urgent demand for all-polymer organic solar cells (AP-OSCs) to gain higher efficiency. Here, we successfully improve the performance to 16.09% by introducing a small amount of BN-T, a B <- N-type polymer acceptor, into the PM6:PY-IT blend. It has been found that BN-T makes the active layer, based on the PM6:PY-IT:BN-T ternary blend, more crystalline but meanwhile slightly reduces the phase separation, leading to enhancement of both exciton harvesting and charge transport. From a thermodynamic viewpoint, BN-T prefers to reside between PM6 and PY-IT, and the fraction of this fine-tunes the morphology. Besides, a significantly reduced nonradiative energy loss occurs in the ternary blend, along with the coexistence of energy and charge transfer between the two acceptors. The progressive performance facilitated by these improved properties demonstrates that AP-OSCs can possibly comparably efficient with those based on small molecule acceptors, further enhancing the competitiveness of this device type.
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| 10. |
- Pan, Junxiu, et al.
(författare)
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pi-Extended Nonfullerene Acceptors for Efficient Organic Solar Cells with a High Open-Circuit Voltage of 0.94 V and a Low Energy Loss of 0.49 eV
- 2021
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 13:19, s. 22531-22539
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Tidskriftsartikel (refereegranskat)abstract
- A combination of high open-circuit voltage (V-oc) and short-circuit current density (J(sc)) typically creates effective organic solar cells (OSCs). Y5, a member of the Y-series acceptors, can achieve high V-oc of 0.94 V with PM6 but low J(sc) of 12.8 mA cm(-2). To maintain the high V-oc while increasing the J(sc) of devices, we developed a new nonfullerene acceptor, namely, BTP-C2C4-N, by extending the conjugation of a Y5 molecule with a naphthalenebased end acceptor. In comparison with Y5-based devices, PM6:BTP-C2C4-N-based devices exhibited significantly higher J(sc) of 18.2 mA cm(-2) followed by a high V-oc. To further increase the photovoltaic properties of BTP-C2C4-N analogues, BTP-C4C6-N and BTP-C6C8-N molecules with better processability and film morphology are obtained by adjusting the alkyl branched chain length. The optimized OSCs based on BTP-C4C6-N with a moderate alkyl branched chain length exhibited the best PCE of 12.4% with a high V-oc of 0.94 V and J(sc) of 20.7 mA cm(-2). Notably, the devices achieved a low energy loss of 0.49 eV (0.51 eV for Y5 system) accompanied by a small nonradiative energy loss. The results indicate that nonfullerene acceptors with extended terminal motifs and optimized branched chain lengths can effectively enhance the performance of OSCs and reduce energy loss.
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| 11. |
- Sun, Huiliang, et al.
(författare)
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A monothiophene unit incorporating both fluoro and ester substitution enabling high-performance donor polymers for non-fullerene solar cells with 16.4% efficiency
- 2019
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Ingår i: Energy & Environmental Science. - : ROYAL SOC CHEMISTRY. - 1754-5692 .- 1754-5706. ; 12:11, s. 3328-3337
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Tidskriftsartikel (refereegranskat)abstract
- Thiophene and its derivatives have been extensively used in organic electronics, particularly in the field of polymer solar cells (PSCs). Significant research efforts have been dedicated to modifying thiophene-based units by attaching electron-donating or withdrawing groups to tune the energy levels of conjugated materials. Herein, we report the design and synthesis of a novel thiophene derivative, FE-T, featuring a monothiophene functionalized with both an electron-withdrawing fluorine atom (F) and an ester group (E). The FE-T unit possesses distinctive advantages of both F and E groups, the synergistic effects of which enable significant downshifting of the energy levels and enhanced aggregation/crystallinity of the resulting organic materials. Shown in this work are a series of polymers obtained by incorporating the FE-T unit into a PM6 polymer to fine-tune the energetics and morphology of this high-performance PSC material. The optimal polymer in the series shows a downshifted HOMO and an improved morphology, leading to a high PCE of 16.4% with a small energy loss (0.53 eV) enabled by the reduced non-radiative energy loss (0.23 eV), which are among the best values reported for non-fullerene PSCs to date. This work shows that the FE-T unit is a promising building block to construct donor polymers for high-performance organic photovoltaic cells.
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| 12. |
- Wang, Yuming, et al.
(författare)
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Origins of the open-circuit voltage in ternary organic solar cells and design rules for minimized voltage losses
- 2023
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Ingår i: Nature Energy. - : NATURE PORTFOLIO. - 2058-7546. ; 8:9, s. 978-988
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Tidskriftsartikel (refereegranskat)abstract
- The power conversion efficiency of ternary organic solar cells (TOSCs), consisting of one host binary blend and one guest component, remains limited by large voltage losses. The fundamental understanding of the open-circuit voltage (V-OC) in TOSCs is controversial, limiting rational design of the guest component. In this study, we systematically investigate how the guest component affects the radiative and non-radiative related parts of V-OC of a series of TOSCs using the detailed balanced principle. We highlight that the thermal population of charge-transfer and local exciton states provided by the guest binary blend (that is, the guest-component-based binary blend) has a significant influence on the non-radiative voltage losses. Ultimately, we provide two design rules for enhancing the V-OC in TOSCs: high emission yield for the guest binary blend and similar charge-transfer-state energies for host/guest binary blends; high miscibility of the guest component with the low gap component in the host binary blend. The performance of ternary organic solar cells is limited by voltage losses. Using the detailed balance principle, Wang et al. show how the third component of the blend affects the open-circuit voltage and delineate molecular design rules.
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| 13. |
- Zhang, Liwei, et al.
(författare)
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Evaluation metrics for an experience-based mobile artificial cognitive system
- 2014
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Ingår i: 11th World Congress on Intelligent Control and Automation (WCICA2014). - : Springer Berlin/Heidelberg. - 9783642289613 ; , s. 2225-2232
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Konferensbidrag (refereegranskat)abstract
- In this paper, an FIM (Fitness to Ideal Model)and a DLen (Description Length) based evaluation approachhas been developed to measure the benefit of learning from experienceto improve the robustness of the robot’s behavior. Theexperience based mobile artificial cognitive system architectureis briefly described and adopted by a PR2 service robot withinthe EU-FP7 funded project RACE. The robot conducts typicaltasks of a waiter. Temporal and lasting obstacles and standardtable items, as shown in the demonstrations of “Deal-withobstacles”and “Clear-table-intelligently”, are being adoptedin this work to test the proposed evaluation metrics, validateit on a real PR2 robot system and present the evaluationresults. The relationship between the FIM and DLen has beenvalidated. This work proposes an effective approach to evaluatea cognitive service robot system which enhances its performanceby learning.
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| 14. |
- Zhang, Xin, et al.
(författare)
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Enhancing the Photovoltaic Performance of Triplet Acceptors Enabled by Side-Chain Engineering
- 2021
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Ingår i: Solar RRL. - : WILEY-V C H VERLAG GMBH. - 2367-198X. ; 5:10
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Tidskriftsartikel (refereegranskat)abstract
- Triplet excitons have both longer lifetimes and diffusion lengths than singlet excitons due to the nature of triplet excitons, which is expected to increase the photocurrent and further improve the performance of organic solar cells (OSCs). However, the working mechanism of triplet excitons in OSCs is not clearly clarified. Therefore, it is urgent to develop new triplet acceptors for in-depth understanding. Herein, a series of acceptors (BTn-4Cl) are synthesized by fine-tuning of the side-chain branch positions. The generation of triplet excitons of BTn-4Cl is confirmed by the time-resolved photoluminescence (TRPL) spectra, magnetophotocurrent (MPC) experiment, and electron paramagnetic resonance (EPR) spectra. The effects of side-chain engineering on the optoelectronic properties, packing behaviors, energy losses, charge transport properties, spin lifetimes of triplet polarons, and blend film morphologies are systematically studied. These results show that D18:BT3-4Cl-based OSCs possess the best power conversion efficiency (PCE) of 17.31% due to lower energy losses, less recombination losses, more balanced charge carrier mobilities, longer spin-lattice (T-1) relaxation time, and more favorable morphology. This work enhances the understanding of the structure-property relationship for high-performance triplet acceptors.
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| 15. |
- Zhang, Xin, et al.
(författare)
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Side-Chain Engineering for Enhancing the Molecular Rigidity and Photovoltaic Performance of Noncovalently Fused-Ring Electron Acceptors
- 2021
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 60:32, s. 17720-17725
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Tidskriftsartikel (refereegranskat)abstract
- Side-chain engineering is an effective strategy to regulate the solubility and packing behavior of organic materials. Recently, a unique strategy, so-called terminal side-chain (T-SC) engineering, has attracted much attention in the field of organic solar cells (OSCs), but there is a lack of deep understanding of the mechanism. Herein, a new noncovalently fused-ring electron acceptor (NFREA) containing two T-SCs (NoCA-5) was designed and synthesized. Introduction of T-SCs can enhance molecular rigidity and intermolecular pi-pi stacking, which is confirmed by the smaller Stokes shift value, lower reorganization free energy, and shorter pi-pi stacking distance in comparison to NoCA-1. Hence, the NoCA-5-based device exhibits a record power conversion efficiency (PCE) of 14.82 % in labs and a certified PCE of 14.5 %, resulting from a high electron mobility, a short charge-extraction time, a small Urbach energy (E-u), and a favorable phase separation.
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| 16. |
- Chai, Gaoda, et al.
(författare)
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Deciphering the Role of Chalcogen-Containing Heterocycles in Nonfullerene Acceptors for Organic Solar Cells
- 2020
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Ingår i: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 5:11, s. 3415-3425
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Tidskriftsartikel (refereegranskat)abstract
- The field of organic solar cells has experienced paradigm-shifting changes in recent years because of the emergence of nonfullerene acceptors (NFAs). It is critically important to gain more insight into the structure-property relationship of the emerging A-DAD-A-type NFAs. In this Letter, a family of NFAs named BPF-4F, BPT-4F, and BPS-4F incorporating various chalcogen-containing heterocycles, i.e., furan, thiophene, and selenophene, respectively, was designed and synthesized. These NFAs exhibited dramatic differences in their photovoltaic performances with device efficiencies of 16.8% achieved by the thiophene-based cells, which was much higher than the furan-based ones (12.6%). In addition, the selenophene-based NFA showed a red-shifted absorption relative to the furan- and thiophene-based ones and obtained a decent efficiency of 16.3% owing to an improved J(SC). The reasons why these NFAs performed differently are systematically studied by comparing their optoelectronic properties and film morphology, which provides new understandings of the molecular design of high-performance NFAs.
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| 17. |
- Gao, Yanhong, et al.
(författare)
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Comparison between past and future extreme precipitations simulated by global and regional climate models over the Tibetan Plateau
- 2018
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 38:3, s. 1285-1297
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Tidskriftsartikel (refereegranskat)abstract
- Past studies on regional climate change over the Tibetan Plateau (TP) have mainly looked at changes in the mean climate. This study focuses on past and future extreme precipitations, simulated by global and regional climate models over the TP. To assess the influence of large-scale forcing on dynamic downscaling using Weather Research and Forecasting (WRF) model, downscaling results for the historical period (1980–2005) with ERA-Interim reanalysis and CCSM4 as forcings are evaluated against a gridded observational data set. These are inter-compared before future projections for the period 2005–2100 under two scenarios (RCP4.5 and RCP8.5). The followings are obtained: (1) the reanalysis greatly overestimates not only the mean, but also extreme precipitation. The overestimation in CCSM4 is even larger than that of the reanalysis. (2) The two downscalings outperform their forcings, reflected by reduced overestimation for extreme precipitation frequency, increased spatial pattern correlations and more accurate linear trends, especially for the downscaling driven by CCSM. This demonstrates the constraining power of the fine-scale modelling and the importance of more realistic representations of surface forcing and related processes in the TP. (3) CCSM4 projects a general wetting across the whole TP with increases of heavy precipitation as well as the wetting intensification with warming. WRF also projects an overall wetting, but the wetting is less sensitive to the warming and there is more of an increase in light precipitation frequency. More importantly, a diverse pattern with wetting in the north and drying in the south is found in the dynamical downscaling in contrast to the uniform wetting in its forcing.
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| 18. |
- Hu, Jutao, et al.
(författare)
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Effects of NH4+ doping on the hydrogen storage properties of metal hydrides
- 2023
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Ingår i: International journal of hydrogen energy. - : Elsevier Ltd. - 0360-3199 .- 1879-3487. ; 48:50, s. 19153-19159
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Tidskriftsartikel (refereegranskat)abstract
- Doping can modify the properties of metal hydrogen storage materials significantly. Currently, the metal doping is a frequent strategy, while the non-metal cation doping has not been examined extensively so far. In this study, the effects of NH4+ doping on the hydrogen storage properties of different metal hydrides, including TiH2, Ti0·25V0·25Nb0·25Zr0·25H2, Ti0·5V0·5H2 and VH2, are investigated by first-principles calculations. It is found that the NH4+ presents a good affinity for metal hydrides and the NH4+ incorporation leads to charge redistribution and formation of dihydrogen bond. Furthermore, the NH4+ doping in metal hydrides is favorable for enhancing the hydrogen storage capacity and decreasing the thermal stability simultaneously. The possible reason for the NH4+ doping induced destabilization in metal hydrides is the relatively weak interaction between NH4+ and hydrogen atoms.
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| 19. |
- Lee, Cheng-Ruei, et al.
(författare)
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Young inversion with multiple linked QTLs under selection in a hybrid zone
- 2017
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Ingår i: NATURE ECOLOGY & EVOLUTION. - : Springer Science and Business Media LLC. - 2397-334X. ; 1:5
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Tidskriftsartikel (refereegranskat)abstract
- Fixed chromosomal inversions can reduce gene flow and promote speciation in two ways: by suppressing recombination and by carrying locally favoured alleles at multiple loci. However, it is unknown whether favoured mutations slowly accumulate on older inversions or if young inversions spread because they capture pre-existing adaptive quantitative trait loci (QTLs). By genetic mapping, chromosome painting and genome sequencing, we have identified a major inversion controlling ecologically important traits in Boechera stricta. The inversion arose since the last glaciation and subsequently reached local high frequency in a hybrid speciation zone. Furthermore, the inversion shows signs of positive directional selection. To test whether the inversion could have captured existing, linked QTLs, we crossed standard, collinear haplotypes from the hybrid zone and found multiple linked phenology QTLs within the inversion region. These findings provide the first direct evidence that linked, locally adapted QTLs may be captured by young inversions during incipient speciation.
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| 20. |
- Liang, Lin, et al.
(författare)
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Non-Interpenetrated Single-Crystal Covalent Organic Frameworks
- 2020
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 59:41, s. 17991-17995
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Tidskriftsartikel (refereegranskat)abstract
- Growth of covalent organic frameworks (COFs) as single crystals is extremely challenging. Inaccessibility of open-structured single-crystal COFs prevents the exploration of structure-oriented applications. Herein we report for the first time a non-interpenetrated single-crystal COF, LZU-306, which possesses the open structure constructed exclusively via covalent assembly. With a high void volume of 80 %, LZU-306 was applied to investigate the intrinsic dynamics of reticulated tetraphenylethylene (TPE) as the individual aggregation-induced-emission moiety. Solid-state(2)H NMR investigation has determined that the rotation of benzene rings in TPE, being the freest among the reported cases, is as fast as 1.0x10(4) Hz at 203 K to 1.5x10(7) Hz at 293 K. This research not only explores a new paradigm for single-crystal growth of open frameworks, but also provides a unique matrix-isolation platform to reticulate functional moieties into a well-defined and isolated state.
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| 21. |
- Liu, Xintao, et al.
(författare)
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Analysis of urban agglomeration structure through spatial network and mobile phone data
- 2021
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Ingår i: Transactions in GIS. - : Wiley. - 1361-1682 .- 1467-9671. ; 25:4, s. 1949-1969
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Tidskriftsartikel (refereegranskat)abstract
- Urban agglomeration is an important strategy used to promote economic development and urbanization in China. Understanding the structure of urban agglomeration is therefore essential for policy-makers and planners. In this study, the Beijing–Tianjin–Hebei urban agglomeration (BTHUG) is explored through a proposed spatial network analytical framework and a large mobile phone data set (over 20 million users). We first construct a weight-directed spatial interaction network based on an origin–destination matrix derived from the data set. Several network metrics (i.e., degree, strength, the rich-club coefficient, and the assortativity coefficient) and three selected community detection algorithms (i.e., Infomap, Louvain, and Regionalization) are applied and compared to reveal the structure of the BTHUG. A four-level hierarchical structure is defined and observed: one global center, two local centers, major cities that have low mobility flow but strong linkages with the three centers, and peripheral cities that have low mobility flow and weak linkages with the three centers. In particular, the results imply that the spatial structure of the BTHUG is over-dependent on the global center (i.e., Beijing and northern Langfang). Further, ignoring spatial interaction patterns in top-down administrative planning for urban agglomeration may lead to ineffective integrated development. The implications for BTHUG planning are discussed.
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| 22. |
- Luo, Zhenghui, et al.
(författare)
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Fine-Tuning Energy Levels via Asymmetric End Groups Enables Polymer Solar Cells with Efficiencies over 17%
- 2020
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Ingår i: Joule. - : CELL PRESS. - 2542-4351. ; 4:6, s. 1236-1247
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Tidskriftsartikel (refereegranskat)abstract
- Generally, it is important to fine-tune the energy levels of donor and acceptor materials in the field of polymer solar cell (PSCs) to achieve a minimal highest occupied molecular orbital (HOMO) energy offset, which yet is still sufficient for charge separation. Based on the high-performance small-molecule acceptor (SMA) of BTP-4F, we modified the end groups of BTP-4F from IC-2F to CPTCN-Cl. It was found that when both end groups were substituted by CPTCN-Cl, the energy level upshift was too large that caused unfavorable energetic alignment, thus poor device performance. By using the strategy of asymmetric end groups, we were able to achieve near optimal energy level match, resulting in higher open-circuit voltage (V-OC) and power conversion efficiency (PCE) compared with those given by the PM6:BTP-4F system. Our strategy can be useful and potentially applied to othermaterial systems for maximizing efficiency of non-fullerene PSCs.
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| 23. |
- Ma, Ruijie, et al.
(författare)
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All-polymer solar cells with over 16% efficiency and enhanced stability enabled by compatible solvent and polymer additives
- 2022
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Ingår i: Aggregate. - : Wiley. - 2692-4560 .- 2766-8541. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- Considering the robust and stable nature of the active layers, advancing the power conversion efficiency (PCE) has long been the priority for all-polymer solar cells (all-PSCs). Despite the recent surge of PCE, the photovoltaic parameters of the state-of-the-art all-PSC still lag those of the polymer:small molecule-based devices. To compete with the counterparts, judicious modulation of the morphology and thus the device electrical properties are needed. It is difficult to improve all the parameters concurrently for the all-PSCs with advanced efficiency, and one increase is typically accompanied by the drop of the other(s). In this work, with the aids of the solvent additive (1-chloronaphthalene) and the n-type polymer additive (N2200), we can fine-tune the morphology of the active layer and demonstrate a 16.04% efficient all-PSC based on the PM6:PY-IT active layer. The grazing incidence wide-angle X-ray scattering measurements show that the shape of the crystallites can be altered, and the reshaped crystallites lead to enhanced and more balanced charge transport, reduced recombination, and suppressed energy loss, which lead to concurrently improved and device efficiency and stability.
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| 24. |
- Majed, Ahmad, et al.
(författare)
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Transition Metal Carbo-Chalcogenide "TMCC": A New Family of 2D Materials
- 2022
-
Ingår i: Advanced Materials. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 34:26
-
Tidskriftsartikel (refereegranskat)abstract
- A new family of 2D transition metal carbo-chalcogenides (TMCCs) is reported, which can be considered a combination of two well-known families, TM carbides (MXenes) and TM dichalcogenides (TMDCs), at the atomic level. Single sheets are successfully obtained from multilayered Nb2S2C and Ta2S2C using electrochemical lithiation followed by sonication in water. The parent multilayered TMCCs are synthesized using a simple, scalable solid-state synthesis followed by a topochemical reaction. A superconductivity transition is observed at 7.55 K for Nb2S2C. The delaminated Nb2S2C outperforms both multilayered Nb2S2C and delaminated NbS2 as an electrode material for Li-ion batteries. Ab initio calculations predict the elastic constant of TMCC to be over 50% higher than that of TMDC.
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| 25. |
- Qi, Zhenyu, et al.
(författare)
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Blueshifting the Absorption of a Small -Molecule Donor and Using it as the Third Component to Achieve High-Efficiency Ternary Organic Solar Cells
- 2022
-
Ingår i: Solar RRL. - : WILEY-V C H VERLAG GMBH. - 2367-198X. ; 6:9
-
Tidskriftsartikel (refereegranskat)abstract
- Adding a small-molecule donor (SMD) to state-of-the-art nonfullerene organic solar cells (OSCs) is demonstrated as a useful strategy to construct ternary organic solar cells, as SMDs typically have high crystallinity and can tune charge transport properties of OSCs. However, the absorption of most SMDs overlaps with typical donor polymers (e.g., PM6), which is against the general guidelines of adopting materials with complementary absorption in ternary OSCs. Herein, the absorption of state-of-art SMDs (BTR-CI) by linking the beta position of the outer thiophene to the alpha position of the inner thiophene unit is intentionally blueshifted. The resulting molecule beta-S1 shows a maximum absorption peak at 505 nm in the film state, which exhibits wider bandgap and shows complementary absorption with the host system (PM6:Y6). The corresponding ternary OSCs with 20%wt beta-S1 show significantly enhanced efficiency from 16.2% to 17.1% due to the increased short-circuit current (J(sc)) and improved fill factor (FF). Herein, an effective strategy to design SMDs with both wider bandgaps and higher crystallinity for high-performance ternary OSCs is presented.
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| 26. |
- Qin, Linqing, et al.
(författare)
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Triplet Acceptors with a D-A Structure and Twisted Conformation for Efficient Organic Solar Cells
- 2020
-
Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 59:35, s. 15043-15049
-
Tidskriftsartikel (refereegranskat)abstract
- Triplet acceptors have been developed to construct high-performance organic solar cells (OSCs) as the long lifetime and diffusion range of triplet excitons may dissociate into free charges instead of net recombination when the energy levels of the lowest triplet state (T-1) are close to those of charge-transfer states ((CT)-C-3). The current triplet acceptors were designed by introducing heavy atoms to enhance the intersystem crossing, limiting their applications. Herein, two twisted acceptors without heavy atoms, analogues of Y6, constructed with large pi-conjugated core and D-A structure, were confirmed to be triplet materials, leading to high-performance OSCs. The mechanism of triplet excitons were investigated to show that the twisted and D-A structures result in large spin-orbit coupling (SOC) and small energy gap between the singlet and triplet states, and thus efficient intersystem crossing. Moreover, the energy level of T-1 is close to (CT)-C-3, facilitating the split of triplet exciton to free charges.
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| 27. |
- Rockel, Sebastian, et al.
(författare)
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Integrating physics-based prediction with semantic plan execution monitoring
- 2015
-
Ingår i: 2015 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS). - : IEEE. - 9781479999941 ; , s. 2883-2888
-
Konferensbidrag (refereegranskat)abstract
- Real-world robotic systems have to deal with uncertain and dynamic environments to reliably perform tasks. State-of-the-art cognitive robotic systems use an abstract symbolic representation of the real world that is used for high level reasoning. Some aspects of the world, such as object dynamics, are inherently difficult to capture in an abstract symbolic form, yet they influence whether the executed action will succeed or fail. This paper presents an integrated system that uses a physics-based simulation for predicting robot action results and durations, combined with a Hierarchical Task Network (HTN) planner and semantic execution monitoring. We describe a fully integrated system performing functional imagination, which is essentially contributed by a Semantic Execution Monitor (SEM). Based on information obtained from functional imagination, the robot control decides whether it is necessary to adapt the plan that is currently being executed. As a proof of concept, we demonstrate PR2 able of carrying objects on a tray without the objects toppling. Our approach achieves this by considering the robot and object dynamics in simulation. A validation shows that robot action results in simulation can be transferred to the real world. The system improves on state-of-the-art AI plan-based systems by feeding simulated prediction results back into the execution system.
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| 28. |
- Shi, Yanan, et al.
(författare)
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Optimizing the Charge Carrier and Light Management of Nonfullerene Acceptors for Efficient Organic Solar Cells with Small Nonradiative Energy Losses
- 2021
-
Ingår i: Solar RRL. - : WILEY-V C H VERLAG GMBH. - 2367-198X. ; 5:4
-
Tidskriftsartikel (refereegranskat)abstract
- The photovoltaic properties and energy losses of organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) are highly dependent on their molecular structures and aggregation morphologies. Charge carrier and light managements are important to optimize NFA molecules. Herein, four NFAs with different alkyl substituents and end groups, named BTP-C11-N2F, BTP-C9-N2F, BTP-C9-IC4F, and BTP-C9-N4F, are designed and synthesized by side-chain shortening, end-acceptor pi-extension, and fluorination. As a result, a favorable morphology is achieved in BTP-C9-N4F-based OSCs by using typical high bandgap polymer PM6 as a donor, and this system obtains the highest power conversion efficiency of 17.0% with a short circuit current (J(sc)) of 26.3 mA cm(-2), an open circuit current (V-oc) of 0.85 V, and a fill factor (FF) of 75.7%. In addition, its light (J(sc)) and charge carrier (V-oc x FF) managements relative to the Shockley-Queisser limit are also increased. Extending the conjugation of the end groups increased the energy levels of NFAs and enabled an E-loss of 0.50 eV with a nonradiative recombination loss of as low as 0.20 eV in BTP-C11-N2F-based OSCs. This work provides an efficient strategy to optimize the molecular structures of nonfullerene acceptors and further improve the properties of OSCs.
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| 29. |
- Sun, Huiliang, et al.
(författare)
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A Narrow-Bandgap n-Type Polymer with an Acceptor-Acceptor Backbone Enabling Efficient All-Polymer Solar Cells
- 2020
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32
-
Tidskriftsartikel (refereegranskat)abstract
- Narrow-bandgap polymer semiconductors are essential for advancing the development of organic solar cells. Here, a new narrow-bandgap polymer acceptor L14, featuring an acceptor-acceptor (A-A) type backbone, is synthesized by copolymerizing a dibrominated fused-ring electron acceptor (FREA) with distannylated bithiophene imide. Combining the advantages of both the FREA and the A-A polymer, L14 not only shows a narrow bandgap and high absorption coefficient, but also low-lying frontier molecular orbital (FMO) levels. Such FMO levels yield improved electron transfer character, but unexpectedly, without sacrificing open-circuit voltage (V-oc), which is attributed to a small nonradiative recombination loss (E-loss,E-nr) of 0.22 eV. Benefiting from the improved photocurrent along with the high fill factor andV(oc), an excellent efficiency of 14.3% is achieved, which is among the highest values for all-polymer solar cells (all-PSCs). The results demonstrate the superiority of narrow-bandgap A-A type polymers for improving all-PSC performance and pave a way toward developing high-performance polymer acceptors for all-PSCs.
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| 30. |
- Wang, Wei, et al.
(författare)
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Enhanced edge detection for polarimetric SAR images using a directional span-driven adaptive window
- 2018
-
Ingår i: International Journal of Remote Sensing. - : TAYLOR & FRANCIS LTD. - 0143-1161 .- 1366-5901. ; 39:19, s. 6340-6357
-
Tidskriftsartikel (refereegranskat)abstract
- Automatic edge detection for polarimetric synthetic aperture radar (PolSAR) images plays a fundamental role in various PolSAR applications. The classic methods apply the fixed-shape windows to detect the edges, whereas their performance is limited in heterogeneous areas. This article presents an enhanced edge detection method for PolSAR data based on the directional span-driven adaptive (DSDA) window. The DSDA window has variable sizes and flexible shapes, and is constructed by adaptively selecting samples that follow the same statistical distribution. Therefore, it can overcome the limitation of classic fixed-shape windows. To obtain refined and reliable edge detection results in heterogeneous urban areas, we adopt the spherically invariant random vector (SIRV) product model since the complex Wishart distribution is often not met. In addition, a span ratio is combined with the SIRV distance to highlight the dissimilarity measure and to improve the robustness of the proposed method. The simulated PolSAR data and three real data sets from experimental synthetic aperture radar, electromagnetics institute synthetic aperture radar, and Radarsat-2 systems are used to validate the performance of the enhanced edge detector. Both quantitative evaluation and visual presentation of the results demonstrate the effectiveness of the proposed method and its superiority over the classic edge detectors.
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| 31. |
- Wang, Wei, et al.
(författare)
-
Enhanced Edge Detection for Polarimetric SAR Images Using Directional Span-Driven Adaptive Window
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Automatic edge detection for polarimetric synthetic aperture radar (PolSAR) images plays a fundamental role in various PolSAR applications. The classic methods apply the fixed-shape windows to detect the edges, whereas their performance is limited in heterogeneous areas. This paper presents an enhanced edge detection method for PolSAR data based on the directional span-driven adaptive (DSDA) window. The DSDA window has variable sizes and flexible shapes, and is constructed by adaptively selecting samples which follow the same statistical distribution. Therefore, it can overcome the limitation of classic fixed-shape windows. To obtain refined and reliable edge detection results in heterogeneous urban areas, we adopt the spherically invariant random vector (SIRV) product model, since the complex Wishart distribution is often not met. In addition, a span ratio is combined with the SIRV distance to highlight the dissimilarity measure and to improve the robustness of the proposed method. The simulated PolSAR data and three real data sets from ESAR, EMISAR and RADARSAT-2 systems are used to validate the performance of the enhanced edge detector. Both quantitative evaluation and visual presentation of the results demonstrate the effectiveness of the proposed method and its superiority over the classic edge detectors.
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| 32. |
- Wang, Wei, et al.
(författare)
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Integrating Contextual Information With H/(alpha)over-bar Decomposition for PolSAR Data Classification
- 2016
-
Ingår i: IEEE Geoscience and Remote Sensing Letters. - : IEEE. - 1545-598X .- 1558-0571. ; 13:12, s. 2034-2038
-
Tidskriftsartikel (refereegranskat)abstract
- The use of contextual information is beneficial to improve both the accuracy and reliability of image classification. Based on the robust fuzzy c-means (RFCM) clustering method and an adaptive Markov random field model, this letter proposes a contextual H/(alpha) over bar classifier for polarimetric synthetic aperture radar images. At each iterative step of RFCM clustering, the prior probability extracted from the local neighborhood is combined with the fuzzy membership derived from inherent polarimetric characteristics, thus the enhanced fuzzy membership is more reliable. In addition, an adaptive smoothing factor is proposed for use during contextual information retrieval, which can prevent oversmoothing and preserve the local spatial details. The experimental results implemented using AIRSAR and ESAR L-band data validate the efficacy of the proposed method. Compared with the iterated Wishart classifier and fuzzy H/(alpha) over bar classifier, the proposed method significantly improves the classification accuracy, with less noise and increased preservation of details.
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| 33. |
- Wang, Wei, et al.
(författare)
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POLSAR IMAGE SEGMENTATION BASED ON HIERARCHICAL REGION MERGING AND SEGMENT REFINEMENT WITH WMRF MODEL
- 2017
-
Ingår i: 2017 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS). - : IEEE. - 9781509049516 ; , s. 4574-4577
-
Konferensbidrag (refereegranskat)abstract
- In this paper, a superpixel-based segmentation method is proposed for PolSAR images by utilizing hierarchical region merging and segment refinement. The loss of the energy function, which determines the consistency of two adjacent regions from the statistical aspect, is applied to guide the merging procedure. In addition to the edge penalty term, the homogeneity measurement is also employed to prevent merging the regions that are from different land covers or objects. Based on the merged segments, the segment refinement is applied to further improve the segmentation accuracy by iteratively relabeling the edge pixels. It uses a maximum a posterior (MAP) criterion using the statistical distribution of the pixels and the Markov random field (MRF) model. The performance of the proposed method is validated on an experimental PolSAR dataset from the ESAR system.
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| 34. |
- Wang, Wei, et al.
(författare)
-
Superpixel-Based Segmentation of Polarimetric SAR Images through Two-Stage Merging
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a superpixel-based segmentation method for multilook polarimetric SAR (PolSAR) data. By exploring the PolSAR statistics, a two-stage merging strategy is proposed to improve the segmentation efficiency and accuracy. First, based on the initial superpixel partition, the Wishart-merging stage (WMS) simultaneously merges the regions in homogeneous areas, which can be modelled by the Wishart distribution. The Wishart energy loss together with the edge penalty is utilized so that the merged superpixels are from the same land cover and without ambiguity. In the second stage, the doubly flexible two-parameter KummerU distribution is applied to better characterize the resultant regions from the WMS, which are usually located in heterogeneous areas. This KummerU-merging stage (KUMS) iteratively merges the adjacent regions based on the KummerU energy loss. In addition, the edge penalty and the proposed homogeneity penalty are also adopted to guide the merging procedure, and prevent merging the regions from distinct land covers. Compared with the classical iterative merging methods, the two-stage merging strategy can improve the efficiency based on the WMS, and increase the segmentation accuracy through the KUMS. Two experimental PolSAR datasets acquired by ESAR and EMISAR system are used to demonstrate the effectiveness of the proposed segmentation method.
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| 35. |
- Wang, Wei, et al.
(författare)
-
Superpixel Segmentation of Polarimetric SAR Data Based on Integrated Distance Measure and Entropy Rate Method
- 2017
-
Ingår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. - : IEEE. - 1939-1404 .- 2151-1535. ; 10:9, s. 4045-4058
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes to integrate two different distances to measure the dissimilarity between neighboring pixels in PolSAR images, and introduces the entropy rate method into PolSAR image superpixel segmentation. Since the Gaussian model is commonly used for homogeneous scenes and less suitable for heterogeneous scenes, we adopt the spherically invariant random vector (SIRV) model to describe the back-scattering characteristics in heterogeneous areas. Moreover, a directional span-driven adaptive (DSDA) region is proposed such that it contains independent and identically distributed samples only, thus it can obtain accurate estimation of the distribution parameters. Using the DSDA region, the Wishart distance and SIRV distance are calculated, and then combined together through a homogeneity measurement. Therefore, the integrated distance takes advantage of the SIRV model and the Gaussian model, and suits both homogeneous and heterogeneous areas. Finally, based on the integrated distance, the superpixel segments are generated using the entropy rate framework. The experimental results on ESAR and PiSAR L-band datasets show that the proposed method can generate homogeneity-adaptive segments, resulting in smooth representation of the land covers in homogeneous areas, and better preserved details in heterogeneous areas.
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| 36. |
- Wei, Yanan, et al.
(författare)
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A universal method for constructing high efficiency organic solar cells with stacked structures
- 2021
-
Ingår i: Energy & Environmental Science. - : ROYAL SOC CHEMISTRY. - 1754-5692 .- 1754-5706. ; 14:4, s. 2314-2321
-
Tidskriftsartikel (refereegranskat)abstract
- The construction of organic solar cells with stacked structures by the sequential deposition (SD) of donor and acceptor films has great potential in industrial production, as it demonstrates little dependence on the ratio of donor and acceptor materials, solvents, and additives. Herein, we present an eco-friendly solvent protection (ESP) method for the fabrication of high-performance OSCs with stacked structures. Several non-aromatic and non-halogenated solvents are employed as protective agents to build SD devices with a configuration of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS Clevios P VP Al 4083)/donor/protective solvent/acceptor/perylene diimide functionalized with amino N-oxide (PDINO)/Al, which shows that n-octane is the optimal choice for SD devices. Nine different SD systems including the fullerene and nonfullerene ones present comparable photovoltaic performance to their BC counterparts, which proves the universality of this ESP method. Significantly, the device of ITO/PEDOT:PSS/D18/N3/PDINO/Al with n-octane as the protective solvent achieves a maximum PCE of 17.52%, which is the record efficiency of SD devices. Furthermore, a protective factor (delta) is proposed to demonstrate the quantitative relationship between delta and PCE after experimental and theoretical investigation, which presents an idea to understand the mechanism and provides a guideline for solvent choices.
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| 37. |
- Wei, Zhongbao, et al.
(författare)
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Multi-stage state of health estimation of lithium-ion battery with high tolerance to heavily-partial charging
- 2022
-
Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 37:6, s. 7432-7442
-
Tidskriftsartikel (refereegranskat)abstract
- State of health (SOH) is critical to the management of lithium-ion battery (LIB) due to its deep insight into the health diagnostic and protection. However, the absence of complete charging data, which is common in practice, risks impairing the charging-based SOH estimators. This paper proposes a multi-stage SOH estimation method with a broad scope of applications, including the unfavorable but practical scenarios of heavily-partial charging. In particular, different sets of health indicators (HIs), covering both the morphological IC features and the voltage entropy information, are extracted from the partial CC charging data with different initial charging voltage to characterize the aging status. Following this endeavor, artificial neural network (ANN)-based HI fusion is proposed to estimate the SOH of LIB precisely in real time. The proposed method is evaluated with long-term aging experiments performed on different types of LIBs. Results validate several superior merits of the proposed method, including high estimation accuracy, high tolerance to partial charging, strong robustness to cell inconsistency, and wide generality to different battery types.
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| 38. |
- Xu, Xiaoxiang, et al.
(författare)
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Nanocarriers for Inner Ear Disease Therapy
- 2021
-
Ingår i: Frontiers in Cellular Neuroscience. - : Frontiers Media SA. - 1662-5102. ; 15
-
Forskningsöversikt (refereegranskat)abstract
- Hearing loss is a common disease due to sensory loss caused by the diseases in the inner ear. The development of delivery systems for inner ear disease therapy is important to achieve high efficiency and reduce side effects. Currently, traditional drug delivery systems exhibit the potential to be used for inner ear disease therapy, but there are still some drawbacks. As nanotechnology is developing these years, one of the solutions is to develop nanoparticle-based delivery systems for inner ear disease therapy. Various nanoparticles, such as soft material and inorganic-based nanoparticles, have been designed, tested, and showed controlled delivery of drugs, improved targeting property to specific cells, and reduced systemic side effects. In this review, we summarized recent progress in nanocarriers for inner ear disease therapy. This review provides useful information on developing promising nanocarriers for the efficient treatment of inner ear diseases and for further clinical applications for inner ear disease therapy.
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| 39. |
- Yao, Huatong, et al.
(författare)
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All-Polymer Solar Cells with over 12% Efficiency and a Small Voltage Loss Enabled by a Polymer Acceptor Based on an Extended Fused Ring Core
- 2020
-
Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Although the field of all-polymer solar cells (all-PSCs) has seen rapid progress in device efficiencies during the past few years, there are limited choices of polymer acceptors that exhibit strong absorption in the near-IR region and achieve high open-circuit voltage (V-OC) at the same time. In this paper, an all-PSC device is demonstrated with a 12.06% efficiency based on a new polymer acceptor (named PT-IDTTIC) that exhibits strong absorption (maximum absorption coefficient: 2.41 x 10(5)cm(-1)) and a narrow optical bandgap (1.49 eV). Compared to previously reported polymer acceptors such as those based on the indacenodithiophene (IDT) core, the indacenodithienothiophene (IDTT) core has further extended fused ring, providing the polymer with extended absorption into the near-IR region and also increases the electron mobility of the polymer. By blending PT-IDTTIC with the donor polymer, PM6, a high-efficiency all-PSC is achieved with a small voltage loss of 0.52 V, without sacrificingJ(SC)and FF, which demonstrates the great potential of high-performance all-PSCs.
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| 40. |
- Yu, Han, et al.
(författare)
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Fluorinated End Group Enables High-Performance All-Polymer Solar Cells with Near-Infrared Absorption and Enhanced Device Efficiency over 14%
- 2021
-
Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorination of end groups has been a great success in developing efficient small molecule acceptors. However, this strategy has not been applied to the development of polymer acceptors. Here, a dihalogenated end group modified by fluorine and bromine atoms simultaneously, namely IC-FBr, is first developed, then employed to construct a new polymer acceptor (named PYF-T) for all-polymer solar cells (all-PSCs). In comparison with its non-fluorinated counterpart (PY-T), PYF-T exhibits stronger and red-shifted absorption spectra, stronger molecular packing and higher electron mobility. Meanwhile, the fluorination on the end groups down-shifts the energy levels of PYF-T, which matches better with the donor polymer PM6, leading to efficient charge transfer and small voltage loss. As a result, an all-PSC based on PM6:PYF-T yields a higher power conversion efficiency (PCE) of 14.1% than that of PM6:PY-T (11.1%), which is among the highest values for all-PSCs reported to date. This work demonstrates the effectiveness of fluorination of end-groups in designing high-performance polymer acceptors, which paves the way toward developing more efficient and stable all-PSCs.
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| 41. |
- Zhang, Jianwei, et al.
(författare)
-
Electrochemical Palladium-Catalyzed Oxidative Carbonylation-Cyclization of Enallenols
- 2022
-
Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 61:49
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, we report an electrochemical oxidative palladium-catalyzed carbonylation-carbocyclization of enallenols to afford gamma-lactones and spirolactones, which proceeds with excellent chemoselectivity. Interestingly, electrocatalysis was found to have an accelerating effect on the rate of the tandem process, leading to a more efficient reaction than that under chemical redox conditions.
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| 42. |
- Zhang, Xin, et al.
(författare)
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High-Performance All-Small-Molecule Organic Solar Cells Enabled by Regio-Isomerization of Noncovalently Conformational Locks
- 2022
-
Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 32:19
-
Tidskriftsartikel (refereegranskat)abstract
- The power conversion efficiencies (PCEs) of organic solar cells (OSCs) have surpassed 19% thanks to the innovation of polymer donors and molecular acceptors. However, the batch-to-batch variations in polymer materials are detrimental to the reproducibility of the device performance. In comparison, small-molecule donors (SMDs) possess some unique advantages, such as well-defined molecular weights, easy purification, and excellent batch-to-batch repeatability. Herein, a pair of regioisomeric SMDs (BT-O1 and BT-O2) has been synthesized with alkoxy groups as S center dot center dot center dot O noncovalently conformational locks (NoCLs) at the inner and outer position, respectively. Theoretical and experimental results reveal that the regioisomeric effect has a significant influence on the light-harvest ability, energy levels, molecular geometries, internal reorganization energy, and packing behaviors for the two SMDs. As a result, BT-O2-based binary device shows an impressive PCE of 13.99%, much higher than that of BT-O1 based one (4.07%), due to the better-aligned energy level, more balanced charge transport, less charge recombination, lower energy loss, and more favorable phase separation. Furthermore, the fullerene derivative PC71BM is introduced into BT-O2:H3 as the third component to achieve a notable PCE of 15.34% (certified 14.6%). Overall, this work reveals that NoCLs is a promising strategy to achieve high-performance SMDs for all-small-molecule OSCs.
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| 43. |
- Zhang, Xin, et al.
(författare)
-
High-Performance Noncovalently Fused-Ring Electron Acceptors for Organic Solar Cells Enabled by Noncovalent Intramolecular Interactions and End-Group Engineering
- 2021
-
Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 60:22, s. 12475-12481
-
Tidskriftsartikel (refereegranskat)abstract
- Noncovalently fused-ring electron acceptors (NFREAs) have attracted much attention in recent years owing to their advantages of simple synthetic routes, high yields and low costs. However, the efficiencies of NFREAs based organic solar cells (OSCs) are still far behind those of fused-ring electron acceptors (FREAs). Herein, a series of NFREAs with S...O noncovalent intramolecular interactions were designed and synthesized with a two-step synthetic route. Upon introducing pi-extended end-groups into the backbones, the electronic properties, charge transport, film morphology, and energy loss were precisely tuned by fine-tuning the degree of multi-fluorination. As a result, a record PCE of 14.53 % in labs and a certified PCE of 13.8 % for NFREAs based devices were obtained. This contribution demonstrated that combining the strategies of noncovalent conformational locks and pi-extended end-group engineering is a simple and effective way to explore high-performance NFREAs.
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| 44. |
- Zhou, Ruimin, et al.
(författare)
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All-small-molecule organic solar cells with over 14% efficiency by optimizing hierarchical morphologies
- 2019
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- The high efficiency all-small-molecule organic solar cells (OSCs) normally require optimized morphology in their bulk heterojunction active layers. Herein, a small-molecule donor is designed and synthesized, and single-crystal structural analyses reveal its explicit molecular planarity and compact intermolecular packing. A promising narrow bandgap small-molecule with absorption edge of more than 930 nm along with our home-designed small molecule is selected as electron acceptors. To the best of our knowledge, the binary all-small-molecule OSCs achieve the highest efficiency of 14.34% by optimizing their hierarchical morphologies, in which the donor or acceptor rich domains with size up to ca. 70 nm, and the donor crystals of tens of nanometers, together with the donor-acceptor blending, are proved coexisting in the hierarchical large domain. All-small-molecule photovoltaic system shows its promising for high performance OSCs, and our study is likely to lead to insights in relations between bulk heterojunction structure and photovoltaic performance.
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