| 1. |
- Miao, Yanfeng, et al.
(författare)
-
Stable and bright formamidinium-based perovskite light-emitting diodes with high energy conversion efficiency
- 2019
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Solution-processable perovskites show highly emissive and good charge transport, making them attractive for low-cost light-emitting diodes (LEDs) with high energy conversion efficiencies. Despite recent advances in device efficiency, the stability of perovskite LEDs is still a major obstacle. Here, we demonstrate stable and bright perovskite LEDs with high energy conversion efficiencies by optimizing formamidinium lead iodide films. Our LEDs show an energy conversion efficiency of 10.7%, and an external quantum efficiency of 14.2% without outcoupling enhancement through controlling the concentration of the precursor solutions. The device shows low efficiency droop, i.e. 8.3% energy conversion efficiency and 14.0% external quantum efficiency at a current density of 300 mA cm(-2), making the device more efficient than state-of-the-art organic and quantum-dot LEDs at high current densities. Furthermore, the half-lifetime of device with benzylamine treatment is 23.7 hr under a current density of 100 mA cm(-2), comparable to the lifetime of near-infrared organic LEDs.
|
|
| 2. |
- Yang, Rong, et al.
(författare)
-
Inhomogeneous degradation in metal halide perovskites
- 2017
-
Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 111:7
-
Tidskriftsartikel (refereegranskat)abstract
- Although the rapid development of organic-inorganic metal halide perovskite solar cells has led to certified power conversion efficiencies of above 20%, their poor stability remains a major challenge, preventing their practical commercialization. In this paper, we investigate the intrinsic origin of the poor stability in perovskite solar cells by using a confocal fluorescence microscope. We find that the degradation of perovskite films starts from grain boundaries and gradually extend to the center of the grains. Firmly based on our findings, we further demonstrate that the device stability can be significantly enhanced by increasing the grain size of perovskite crystals. Our results have important implications to further enhance the stability of optoelectronic devices based on metal halide perovskites. Published by AIP Publishing.
|
|
| 3. |
- Yang, Rong, et al.
(författare)
-
Oriented Quasi-2D Perovskites for High Performance Optoelectronic Devices
- 2018
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:51
-
Tidskriftsartikel (refereegranskat)abstract
- Quasi-2D layered organometal halide perovskites have recently emerged as promising candidates for solar cells, because of their intrinsic stability compared to 3D analogs. However, relatively low power conversion efficiency (PCE) limits the application of 2D layered perovskites in photovoltaics, due to large energy band gap, high exciton binding energy, and poor interlayer charge transport. Here, efficient and water-stable quasi-2D perovskite solar cells with a peak PCE of 18.20% by using 3-bromobenzylammonium iodide are demonstrated. The unencapsulated devices sustain over 82% of their initial efficiency after 2400 h under relative humidity of approximate to 40%, and show almost unchanged photovoltaic parameters after immersion into water for 60 s. The robust performance of perovskite solar cells results from the quasi-2D perovskite films with hydrophobic nature and a high degree of electronic order and high crystallinity, which consists of both ordered large-bandgap perovskites with the vertical growth in the bottom region and oriented small-bandgap components in the top region. Moreover, due to the suppressed nonradiative recombination, the unencapsulated photovoltaic devices can work well as light-emitting diodes (LEDs), exhibiting an external quantum efficiency of 3.85% and a long operational lifetime of approximate to 96 h at a high current density of 200 mA cm(-2) in air.
|
|
| 4. |
- Chen, Haoran, et al.
(författare)
-
Decoupling engineering of formamidinium-cesium perovskites for efficient photovoltaics
- 2022
-
Ingår i: National Science Review. - : Oxford University Press. - 2095-5138 .- 2053-714X. ; 9:10
-
Tidskriftsartikel (refereegranskat)abstract
- Sequential Cs incorporation strategy is developed to decouple crystallization of FACs perovskite with reduced electron-phonon coupling, resulting in highly stable FACs tri-iodide perovskite photovoltaics with record efficiency. Although pure formamidinium iodide perovskite (FAPbI(3)) possesses an optimal gap for photovoltaics, their poor phase stability limits the long-term operational stability of the devices. A promising approach to enhance their phase stability is to incorporate cesium into FAPbI(3). However, state-of-the-art formamidinium-cesium (FA-Cs) iodide perovskites demonstrate much worse efficiency compared with FAPbI(3), limited by the different crystallization dynamics of formamidinium and cesium, which result in poor composition homogeneity and high trap densities. We develop a novel strategy of crystallization decoupling processes of formamidinium and cesium via a sequential cesium incorporation approach. As such, we obtain highly reproducible, highly efficient and stable solar cells based on FA(1)(-)(x)Cs(x)PbI(3) (x = 0.05-0.16) films with uniform composition distribution in the nanoscale and low defect densities. We also revealed a new stabilization mechanism for Cs doping to stabilize FAPbI(3), i.e. the incorporation of Cs into FAPbI(3) significantly reduces the electron-phonon coupling strength to suppress ionic migration, thereby improving the stability of FA-Cs-based devices.
|
|
| 5. |
- Nie, Shisong, et al.
(författare)
-
High Conductivity, Semiconducting, and Metallic PEDOT:PSS Electrode for All-Plastic Solar Cells
- 2023
-
Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 28:6
-
Tidskriftsartikel (refereegranskat)abstract
- Plastic electrodes are desirable for the rapid development of flexible organic electronics. In this article, a plastic electrode has been prepared by employing traditional conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and plastic substrate polyethersulfone (PES). The completed electrode (Denote as HC-PEDOT:PSS) treated by 80% concentrated sulfuric acid (H2SO4) possesses a high electrical conductivity of over 2673 S/cm and a high transmittance of over 90% at 550 nm. The high conductivity is attributed to the regular arrangement of PEDOT molecules, which has been proved by the X-ray diffraction characterization. Temperature-dependent conductivity measurement reveals that the HC-PEDOT:PSS possesses both semiconducting and metallic properties. The binding force and effects between the PEDOT and PEI are investigated in detail. All plastic solar cells with a classical device structure of PES/HC-PEDOT:PSS/PEI/P3HT:ICBA/EG-PEDOT:PSS show a PCE of 4.05%. The ITO-free device with a structure of Glass/HC-PEDOT:PSS/Al4083/PM6:Y6/PDINO/Ag delivers an open-circuit voltage (V-OC) of 0.81 V, short-circuit current (J(SC) ) of 23.5 mA/cm(2), fill factor (FF) of 0.67 and a moderate power conversion efficiency (PCE) of 12.8%. The above results demonstrate the HC-PEDOT:PSS electrode is a promising candidate for all-plastic solar cells and ITO-free organic solar cells.
|
|
| 6. |
- Wang, Nana, et al.
(författare)
-
Perovskite light-emitting diodes based on solution-processed self-organized multiple quantum wells
- 2016
-
Ingår i: Nature Photonics. - : NATURE PUBLISHING GROUP. - 1749-4885 .- 1749-4893. ; 10:11, s. 699-
-
Tidskriftsartikel (refereegranskat)abstract
- Organometal halide perovskites can be processed from solutions at low temperatures to form crystalline direct-bandgap semiconductors with promising optoelectronic properties(1-5). However, the efficiency of their electroluminescence is limited by non-radiative recombination, which is associated with defects and leakage current due to incomplete surface coverage(6-9). Here we demonstrate a solution-processed perovskite light-emitting diode (LED) based on self-organized multiple quantum wells (MQWs) with excellent film morphologies. The MQW-based LED exhibits a very high external quantum efficiency of up to 11.7%, good stability and exceptional highpower performance with an energy conversion efficiency of 5.5% at a current density of 100 mA cm(-2). This outstanding performance arises because the lower bandgap regions that generate electroluminescence are effectively confined by perovskite MQWs with higher energy gaps, resulting in very efficient radiative decay. Surprisingly, there is no evidence that the large interfacial areas between different bandgap regions cause luminescence quenching.
|
|
| 7. |
- Xu, Weidong, 1988-, et al.
(författare)
-
Rational molecular passivation for high-performance perovskite light-emitting diodes
- 2019
-
Ingår i: Nature Photonics. - : Springer Nature Publishing AG. - 1749-4885 .- 1749-4893. ; 13:6, s. 418-424
-
Tidskriftsartikel (refereegranskat)abstract
- A major efficiency limit for solution-processed perovskite optoelectronic devices, for example light-emitting diodes, is trap-mediated non-radiative losses. Defect passivation using organic molecules has been identified as an attractive approach to tackle this issue. However, implementation of this approach has been hindered by a lack of deep understanding of how the molecular structures influence the effectiveness of passivation. We show that the so far largely ignored hydrogen bonds play a critical role in affecting the passivation. By weakening the hydrogen bonding between the passivating functional moieties and the organic cation featuring in the perovskite, we significantly enhance the interaction with defect sites and minimize non-radiative recombination losses. Consequently, we achieve exceptionally high-performance near-infrared perovskite light-emitting diodes with a record external quantum efficiency of 21.6%. In addition, our passivated perovskite light-emitting diodes maintain a high external quantum efficiency of 20.1% and a wall-plug efficiency of 11.0% at a high current density of 200 mA cm−2, making them more attractive than the most efficient organic and quantum-dot light-emitting diodes at high excitations.
|
|
| 8. |
- Zhang, Liangdong, et al.
(författare)
-
Bright Free Exciton Electroluminescence from Mn-Doped Two-Dimensional Layered Perovskites
- 2019
-
Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 10:11, s. 3171-3175
-
Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional (2D) perovskites incorporating hydrophobic organic spacer cations show improved film stability and morphology compared to their three-dimensional (3D) counterparts. However, 2D perovskites usually exhibit low photoluminescence quantum efficiency (PLQE) owing to strong exciton-phonon interaction at room temperature, which limits their efficiency in light-emitting diodes (LEDs). Here, we demonstrate that the device performance of 2D perovskite LEDs can be significantly enhanced by doping Mn(2+)in (benzimidazolium)(2)PbI4 2D perovskite films to suppress the exciton-phonon interaction. The distorted [PbI6](4-) octahedra by Mn-doping and the rigid benzimidazolium (BIZ) ring without branched chains in the 2D perovskite structure lead to improved crystallinity and rigidity of the perovskites, resulting in suppressed phonon-exciton interaction and enhanced PLQE. On the basis of this strategy, for the first time, we report yellow electroluminescence from free excitons in 2D (n = 1) perovskites with a maximum brightness of 225 cd m(-2) and a peak EQE of 0.045%.
|
|
| 9. |
- Zou, Wei, et al.
(författare)
-
Minimising efficiency roll-off in high-brightness perovskite light-emitting diodes
- 2018
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Efficiency roll-off is a major issue for most types of light-emitting diodes (LEDs), and its origins remain controversial. Here we present investigations of the efficiency roll-off in perovskite LEDs based on two-dimensional layered perovskites. By simultaneously measuring electroluminescence and photoluminescence on a working device, supported by transient photoluminescence decay measurements, we conclude that the efficiency roll-off in perovskite LEDs is mainly due to luminescence quenching which is likely caused by non-radiative Auger recombination. This detrimental effect can be suppressed by increasing the width of quantum wells, which can be easily realized in the layered perovskites by tuning the ratio of large and small organic cations in the precursor solution. This approach leads to the realization of a perovskite LED with a record external quantum efficiency of 12.7%, and the efficiency remains to be high, at approximately 10%, under a high current density of 500 mA cm(-2).
|
|
| 10. |
- Gennemark, Peter, et al.
(författare)
-
An oral antisense oligonucleotide for PCSK9 inhibition
- 2021
-
Ingår i: Science Translational Medicine. - : AMER ASSOC ADVANCEMENT SCIENCE. - 1946-6234 .- 1946-6242. ; 13:593
-
Tidskriftsartikel (refereegranskat)abstract
- Inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9) reduce low-density lipoprotein (LDL) cholesterol and are used for treatment of dyslipidemia. Current PCSK9 inhibitors are administered via subcutaneous injection. We present a highly potent, chemically modified PCSK9 antisense oligonucleotide (ASO) with potential for oral delivery. Past attempts at oral delivery using earlier-generation ASO chemistries and transient permeation enhancers provided encouraging data, suggesting that improving potency of the ASO could make oral delivery a reality. The constrained ethyl chemistry and liver targeting enabled by N-acetylgalactosamine conjugation make this ASO highly potent. A single subcutaneous dose of 90 mg reduced PCSK9 by >90% in humans with elevated LDL cholesterol and a monthly subcutaneous dose of around 25 mg is predicted to reduce PCSK9 by 80% at steady state. To investigate the feasibility of oral administration, the ASO was coformulated in a tablet with sodium caprate as permeation enhancer. Repeated oral daily dosing in dogs resulted in a bioavailability of 7% in the liver (target organ), about fivefold greater than the plasma bioavailability. Target engagement after oral administration was confirmed by intrajejunal administration of a rat-specific surrogate ASO in solution with the enhancer to rats and by plasma PCSK9 and LDL cholesterol lowering in cynomolgus monkey after tablet administration. On the basis of an assumption of 5% liver bioavailability after oral administration in humans, a daily dose of 15 mg is predicted to reduce circulating PCSK9 by 80% at steady state, supporting the development of the compound for oral administration to treat dyslipidemia.
|
|
| 11. |
- Giuri, Antonella, et al.
(författare)
-
Ultra-Bright Near-Infrared Perovskite Light-Emitting Diodes with Reduced Efficiency Roll-off
- 2018
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, an insulating biopolymer is exploited to guide the controlled formation of micro/nano-structure and physical confinement of alpha-delta mixed phase crystalline grains of formamidinium lead iodide (FAPbI(3)) perovskite, functioning as charge carrier concentrators and ensuring improved radiative recombination and photoluminescence quantum yield (PLQY). This composite material is used to build highly efficient near-infrared (NIR) FAPbI(3) Perovskite light-emitting diodes (PeLEDs) that exhibit a high radiance of 206.7 W/sr*m(2), among the highest reported for NIR-PeLEDs, obtained at a very high current density of 1000 mA/cm(2), while importantly avoiding the efficiency roll-off effect. In depth photophysical characterization allows to identify the possible role of the biopolymer in i) enhancing the radiative recombination coefficient, improving light extraction by reducing the refractive index, or ii) enhancing the effective optical absorption because of dielectric scattering at the polymer-perovskite interfaces. Our study reveals how the use of insulating matrixes for the growth of perovskites represents a step towards high power applications of PeLEDs.
|
|
| 12. |
- Jin, Yingzhi, et al.
(författare)
-
Laminated Free Standing PEDOT:PSS Electrode for Solution Processed Integrated Photocapacitors via Hydrogen-Bond Interaction
- 2017
-
Ingår i: ADVANCED MATERIALS INTERFACES. - : WILEY. - 2196-7350. ; 4:23
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a novel lamination method employing hydrogen-bond interaction to assemble a highly conductive free standing poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film as a common electrode is demonstrated in a solution processed metal-free foldable integrated photocapacitor (IPC) composed of a monolithic organic solar cell (OSC) and a capacitor. The highlights of the work are:(1) micrometer free standing PEDOT:PSS electrode is successfully laminated onto a relatively large area (1 cm(2)) OSCs; (2) a free standing capacitor based on the PEDOT:PSS electrode is achieved; (3) the IPC demonstrates an overall efficiency of 2% and an energy storage efficiency of 58%, which is comparable with those of IPCs based on metallic common electrodes; (4) the novel lamination method for PEDOT:PSS electrode enables free standing PEDOT:PSS broad applications in solution processed flexible organic electronics, especially tandem or/and integrated organic electronic devices. Furthermore, the IPC is foldable with excellent cycling stability (no decay after 100 recycles at 1 mA cm(-2)). These results indicate that free standing PEDOT:PSS film is a promising candidate as common electrodes for IPCs to break the restrictions of metal electrodes. The demonstrated lamination method will greatly extend the applications of PEDOT:PSS electrodes to large area flexible organic electronic devices.
|
|
| 13. |
- Larson, Richard A, et al.
(författare)
-
Imatinib pharmacokinetics and its correlation with response and safety in chronic-phase chronic myeloid leukemia: a subanalysis of the IRIS study.
- 2008
-
Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 111:8, s. 4022-8
-
Tidskriftsartikel (refereegranskat)abstract
- Imatinib at 400 mg daily is standard treatment for chronic myeloid leukemia in chronic phase. We here describe the correlation of imatinib trough plasma concentrations (C(mins)) with clinical responses, event-free survival (EFS), and adverse events (AEs). Trough level plasma samples were obtained on day 29 (steady state, n = 351). Plasma concentrations of imatinib and its metabolite CGP74588 were determined by liquid chromatography/mass spectrometry. The overall mean (+/- SD, CV%) steady-state C(min) for imatinib and CGP74588 were 979 ng/mL (+/- 530 ng/mL, 54.1%) and 242 ng/mL (+/- 106 ng/mL, 43.6%), respectively. Cumulative estimated complete cytogenetic response (CCyR) and major molecular response (MMR) rates differed among the quartiles of imatinib trough levels (P = .01 for CCyR, P = .02 for MMR). C(min) of imatinib was significantly higher in patients who achieved CCyR (1009 +/- 544 ng/mL vs 812 +/- 409 ng/mL, P = .01). Patients with high imatinib exposure had better rates of CCyR and MMR and EFS. An exploratory analysis demonstrated that imatinib trough levels were predictive of higher CCyR independently of Sokal risk group. AE rates were similar among the imatinib quartile categories except fluid retention, rash, myalgia, and anemia, which were more common at higher imatinib concentrations. These results suggest that an adequate plasma concentration of imatinib is important for a good clinical response. This study is registered at http://clinicaltrials.gov as NCT00333840.
|
|
| 14. |
- Liu, Yanfeng, et al.
(författare)
-
In Situ Optical Spectroscopy Demonstrates the Effect of Solvent Additive in the Formation of All-Polymer Solar Cells
- 2022
-
Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 13:50, s. 11696-11702
-
Tidskriftsartikel (refereegranskat)abstract
- 1-Chloronaphthalene (CN) has been a common solvent additive in both fullerene- A nd nonfullerene-based organic solar cells. In spite of this, its working mechanism is seldom investigated, in particular, during the drying process of bulk heterojunctions composed of a donor:acceptor mixture. In this work, the role of CN in all-polymer solar cells is investigated by in situ spectroscopies and ex situ characterization of blade-coated PBDB-T:PF5-Y5 blends. Our results suggest that the added CN promotes self-aggregation of polymer donor PBDB-T during the drying process of the blend film, resulting in enhanced crystallinity and hole mobility, which contribute to the increased fill factor and improved performance of PBDB-T:PF5-Y5 solar cells. Besides, the nonradiative energy loss of the corresponding device is also reduced by the addition of CN, corresponding to a slightly increased open-circuit voltage. Overall, our observations deepen our understanding of the drying dynamics, which may guide further development of all-polymer solar cells.
|
|
| 15. |
- Shao, Wei, et al.
(författare)
-
CD44/CD70 blockade and anti-CD154/LFA-1 treatment synergistically suppress accelerated rejection and prolong cardiac allograft survival in mice.
- 2011
-
Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 1365-3083 .- 0300-9475. ; 74, s. 430-437
-
Tidskriftsartikel (refereegranskat)abstract
- Current treatments that are efficient in controlling effector T cells responses to allografts have limited efficacy on the accelerated rejection mediated by memory T cells. Effective targeting of alloreactive memory T cells may therefore be explored to improve therapeutic approaches towards solving this problem. In this study, we investigated the synergistic effect of CD44/CD70 blockade and anti-CD154/LFA-1 treatment on the accelerated rejection mediated by memory T cells. While CD44/CD70 blockade had limited effects on the alloresponses of effector T cells in vivo, it diminished the expansion of both CD4(+) and CD8(+) memory T cells in recipients adoptively transferred with donor-sensitized T cells. In combination with anti-CD154/LFA-1 treatment, CD44/CD70 blockade significantly prolonged cardiac allograft survival in adoptive transfer recipients. We demonstrated that treatment with the combination of all four antibodies (anti-CD154/LFA-1/CD44/CD70) inhibited accelerated rejection by markedly suppressing the alloresponses of effector and memory T cells and reducing the number of graft-infiltration lymphocytes in adoptive transfer recipients. Meanwhile, CD44/CD70 blockade and anti-CD154/LFA-1 treatment synergically enhanced regulatory T cells (Tregs) by increasing the proportion of splenic Tregs and the expression of IL-10 in these recipients. Our findings contribute to the potential design of therapies for accelerated allograft rejection.
|
|
| 16. |
- Shi, Xiaobo, et al.
(författare)
-
Optical Energy Losses in Organic-Inorganic Hybrid Perovskite Light-Emitting Diodes
- 2018
-
Ingår i: Advanced Optical Materials. - : John Wiley & Sons. - 2162-7568 .- 2195-1071. ; 6:17
-
Tidskriftsartikel (refereegranskat)abstract
- Light-emitting diodes (LEDs) based on organic-inorganic hybrid perovskites, in particular, 3D and quasi-2D ones, are in the fast development and their external quantum efficiencies (EQEs) have exceeded 10%, making them competitive candidates toward large-area and low-cost light-emitting applications allowing printing techniques. Similar to other LED categories, light out-coupling efficiency is an important parameter determining the EQE of perovskite LEDs (PeLEDs), which, however, is scarcely studied, limiting further efficiency improvement and understanding of PeLEDs. In this work, for the first time, optical energy losses in PeLEDs are investigated through systematic optical simulations, which reveal that the 3D and quasi-2D PeLEDs can achieve theoretically maximum EQEs of approximate to 25% and approximate to 20%, respectively, in spite of their high refractive indices. These results are consistent with the reported experimental data. This work presents primary understanding of the optical energy losses in PeLEDs and will spur new developments in the aspects of device engineering and light extraction techniques to boost the EQEs of PeLEDs.
|
|
| 17. |
- Wang, Jing, et al.
(författare)
-
A dynamic firefly algorithm based on two-way guidance and dimensional mutation
- 2022
-
Ingår i: International Journal of Bio-Inspired Computation (IJBIC). - : Inderscience Publishers. - 1758-0366 .- 1758-0374. ; 20:2, s. 126-126
-
Tidskriftsartikel (refereegranskat)abstract
- As a stochastic optimiser, the firefly algorithm (FA) has been successfully and widely used in the solutions to various optimisation problems. Recent related research shows that the standard FA does not sufficiently balance between exploration and exploitation. Especially in high-dimensional problems, it is easy for the standard FA to fall into the local optimum and lead to premature convergence. To overcome the problems as mentioned above, DMTgFA uses three strategies: dynamic step length setting strategy (DS), non-elite two-way guidance model (TG) and elites dimensional mutation strategy (DM). The dynamic step length setting strategy makes the algorithm convergence speed faster. The non-elite two-way guidance model and the elite dimensional mutation strategy cooperate to solve the balance problem between global search and local search. Experimental results show that DMTgFA has stronger optimisation ability and faster convergence speed than other state-of-the-art FA variants.
|
|
| 18. |
- Wang, Yanfeng, et al.
(författare)
-
Coarse-grained molecular dynamics investigation of nanostructures and thermal properties of porous anode for solid oxide fuel cell
- 2014
-
Ingår i: Journal of Power Sources. - : Elsevier BV. - 1873-2755 .- 0378-7753. ; 254, s. 209-217
-
Tidskriftsartikel (refereegranskat)abstract
- Incorporation of nanoscale catalysts into porous structures of SOFC has been proven highly successful in increasing active sites and catalyst utilization. In addition, electrochemical reactions as well as heat transfer process in porous anode are strongly affected by complex porous structures. It is believed that study of anode thermal properties are critical for SOFC design and operation. In this work, an AA model is developed for nickel and YSZ components via ASE, and a CG technique is further applied to represent Ni and YSZ beads by VMD, which are then self-assembled to capture the anode nanostructure via GROMACS. LAMMPS is then employed to evaluate average thermal properties of the porous anode. It is found that, at low Ni content (<= 30 vol%), thermal conductivity increases with increasing temperature due to lattice vibrations. Instead, the anode exhibits metallic behavior due to rich nickel phase. Thermal expansion of the anode increases with increasing nickel content. Average thermal properties of the anode are validated by open literature data with good agreement. This approach is considered to be applied to analyze nanostructures, heat transfer and temperature distribution in the porous anode, and is also useful to capture thermal performance of SOFC and stack. (c) 2014 Elsevier B.V. All rights reserved.
|
|
| 19. |
- Wu, Chao, et al.
(författare)
-
Manifestation of Interactions of Nano-Silica in Silicone Rubber Investigated by Low-Frequency Dielectric Spectroscopy and Mechanical Tests
- 2019
-
Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- Silicone rubber composites filled with nano-silica are currently widely used as high voltage insulating materials in power transmission and substation systems. We present a systematic study on the dielectric and mechanical performance of silicone rubber filled with surface modified and unmodified fumed nano-silica. The results indicate that the different interfaces between the silicone rubber and the two types of nano-silica introduce changes in their dielectric response when electrically stressed by a sinusoidal excitation in the frequency range of 10(-4)-1 Hz. The responses of pure silicone rubber and the composite filled with modified silica can be characterized by a paralleled combination of Maxwell-Wagner-Sillars interface polarization and DC conduction. In contrast, the silicone rubber composite with the unmodified nano-silica exhibits a quasi-DC (Q-DC) transport process. The mechanical properties of the composites (represented by their stress-strain characteristics) reveal an improvement in the mechanical strength with increasing filler content. Moreover, the strain level of the composite with a modified filler is improved.
|
|
| 20. |
- Yuan, Zhongcheng, et al.
(författare)
-
Unveiling the synergistic effect of precursor stoichiometry and interfacial reactions for perovskite light-emitting diodes
- 2019
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites are emerging as promising semiconductors for cost-effective and high-performance light-emitting diodes (LEDs). Previous investigations have focused on the optimisation of the emissive perovskite layer, for example, through quantum confinement to enhance the radiative recombination or through defect passivation to decrease non-radiative recombination. However, an in-depth understanding of how the buried charge transport layers affect the perovskite crystallisation, though of critical importance, is currently missing for perovskite LEDs. Here, we reveal synergistic effect of precursor stoichiometry and interfacial reactions for perovskite LEDs, and establish useful guidelines for rational device optimization. We reveal that efficient deprotonation of the undesirable organic cations by a metal oxide interlayer with a high isoelectric point is critical to promote the transition of intermediate phases to highly emissive perovskite films. Combining our findings with effective defect passivation of the active layer, we achieve high-efficiency perovskite LEDs with a maximum external quantum efficiency of 19.6%.
|
|
