| 1. |
- Wu, Jingnan, et al.
(författare)
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Carboxylate substituted pyrazine: A simple and low-cost building block for novel wide bandgap polymer donor enables 15.3% efficiency in organic solar cells
- 2021
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Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855. ; 82
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Tidskriftsartikel (refereegranskat)abstract
- In addition to high power conversion efficiency (PCE) and good stability, the low-cost of photovoltaic materials is also very important for the practical application of organic solar cells (OSCs). Herein, we synthesized a carboxylate substituted pyrazine-based electron-deficient building block (DTCPz) with a simple structure and low synthetic cost, and then developed a novel wide bandgap polymer donor PFBCPZ. Due to the synergistic electron-withdrawing effects of the fluorination in donor unit (BDT-TF) and esterification and C=N double-bond in DTCPz unit, PFBCPZ shows a deeper HOMO level of −5.60 eV, a strong intermolecular π-π interaction, good crystallinity and stacking, and high hole-mobility of 2.11 × 10−3 cm2 V−1 s−1. Matched with a low bandgap acceptor IT-4F, excellent charge transfer, weak recombination, and small non-radiative energy loss in OSCs was achieved, resulting in an impressive fill factor of 0.785 and a high open-circuit voltage of 0.92 V. As a result, a PCE of up to 15.3% is obtained in OSCs, which is the highest value in the IT-4F-based binary OSCs so far and indicates that low-cost DTCPz with a simple structure is a promising building block to construct high-performance polymer donors for application in efficient OSCs.
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| 2. |
- Hassler, Donald M., et al.
(författare)
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Mars’ surface radiation environment measured with the Mars Science Laboratory’s Curiosity Rover
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 343:6169
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Tidskriftsartikel (refereegranskat)abstract
- The Radiation Assessment Detector (RAD) on the Mars Science Laboratory’s Curiosity rover began making detailed measurements of the cosmic ray and energetic particle radiation environment on the surface of Mars on 7 August 2012. We report and discuss measurements of the absorbed dose and dose equivalent from galactic cosmic rays and solar energetic particles on the martian surface for ~300 days of observations during the current solar maximum. These measurements provide insight into the radiation hazards associated with a human mission to the surface of Mars and provide an anchor point with which to model the subsurface radiation environment, with implications for microbial survival times of any possible extant or past life, as well as for the preservation of potential organic biosignatures of the ancient martian environment.
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| 3. |
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| 4. |
- Kim, Myung-Hee Y., et al.
(författare)
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Comparison of Martian surface ionizing radiation measurements from MSL-RAD with Badhwar-O'Neill 2011/HZETRN model calculations
- 2014
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 119:6, s. 1311-1321
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Tidskriftsartikel (refereegranskat)abstract
- Dose rate measurements from Mars Science Laboratory-radiation assessment detector (MSL-RAD) for 300 sols on Mars are compared to simulation results using the Badhwar-O'Neill 2011 galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation is used. Daily atmospheric pressure is measured at Gale Crater by the MSL Rover Environmental Monitoring Station. Particles impinging on top of the Martian atmosphere reach RAD after traversing varying depths of atmosphere that depend on the slant angles, and the model accounts for shielding of the RAD “E” detector (used for dosimetry) by the rest of the instrument. Simulation of average dose rate is in good agreement with RAD measurements for the first 200 sols and reproduces the observed variation of surface dose rate with changing heliospheric conditions and atmospheric pressure. Model results agree less well between sols 200 and 300 due to subtleties in the changing heliospheric conditions. It also suggests that the average contributions of albedo particles (charge number Z < 3) from Martian regolith comprise about 10% and 42% of the average daily point dose and dose equivalent, respectively. Neutron contributions to tissue-averaged effective doses will be reduced compared to point dose equivalent estimates because a large portion of the neutron point dose is due to low-energy neutrons with energies.
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| 5. |
- Rafkin, Scot C.R., et al.
(författare)
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Diurnal variations of energetic particle radiation at the surface of Mars as observed by the Mars Science Laboratory Radiation Assessment Detector
- 2014
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 119:6, s. 1345-1358
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Tidskriftsartikel (refereegranskat)abstract
- The Radiation Assessment Detector onboard the Mars Science Laboratory rover Curiosity is detecting the energetic particle radiation at the surface of Mars. Data collected over the first 350 Martian days of the nominal surface mission show a pronounced diurnal cycle in both the total dose rate and the neutral particle count rate. The diurnal variations detected by the Radiation Assessment Detector were neither anticipated nor previously considered in the literature. These cyclic variations in dose rate and count rate are shown to be the result of changes in atmospheric column mass driven by the atmospheric thermal tide that is characterized through pressure measurements obtained by the Rover Environmental Monitoring Station, also onboard the rover. In addition to bulk changes in the radiation environment, changes in atmospheric shielding forced by the thermal tide are shown to disproportionately affect heavy ions compared to H and He nuclei.
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| 6. |
- Sánchez-Cano, Beatriz, et al.
(författare)
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Mars’ plasma system. Scientific potential of coordinated multipoint missions : "The next generation"
- 2022
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Ingår i: Experimental astronomy. - : Springer. - 0922-6435 .- 1572-9508. ; 54, s. 641-676
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this White Paper, submitted to ESA’s Voyage 2050 call, is to get a more holistic knowledge of the dynamics of the Martian plasma system, from its surface up to the undisturbed solar wind outside of the induced magnetosphere. This can only be achieved with coordinated multi-point observations with high temporal resolution as they have the scientific potential to track the whole dynamics of the system (from small to large scales), and they constitute the next generation of the exploration of Mars analogous to what happened at Earth a few decades ago. This White Paper discusses the key science questions that are still open at Mars and how they could be addressed with coordinated multipoint missions. The main science questions are: (i) How does solar wind driving impact the dynamics of the magnetosphere and ionosphere? (ii) What is the structure and nature of the tail of Mars’ magnetosphere at all scales? (iii) How does the lower atmosphere couple to the upper atmosphere? (iv) Why should we have a permanent in-situ Space Weather monitor at Mars? Each science question is devoted to a specific plasma region, and includes several specific scientific objectives to study in the coming decades. In addition, two mission concepts are also proposed based on coordinated multi-point science from a constellation of orbiting and ground-based platforms, which focus on understanding and solving the current science gaps.
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| 7. |
- Wu, Jingnan, 1994, et al.
(författare)
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Modulating the nanoscale morphology on carboxylate-pyrazine containing terpolymer toward 17.8% efficiency organic solar cells with enhanced thermal stability
- 2022
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 446
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Tidskriftsartikel (refereegranskat)abstract
- It had been commonly accepted in the organic photovoltaic (OPV) community that subtle variations in the molecular structure of active layer materials would cause profound impacts on their aggregating structure and blend morphology and therefore the performance of such polymer solar cells (PSCs). Herein, we employed an electron-deficient building block 3,6-dithiophenyl-2-carboxylate pyrazine (DTCPz) for constructing one series of promising donor terpolymers of PMZ1, PMZ2, and PMZ3, respectively, gaining their relatively lower-lying highest occupied molecular orbital (HOMO) energy levels, more closed π-π stacking and enhanced crystallinity in thin films, and lower miscibility with acceptor Y6, in comparison with their parent polymer counterpart (namely PM6). Reaching DTCPz moieties up to 20% (mol/mol%) in its terpolymer composition, the resulting polymer (PMZ2) achieved more favorable phase separation with improved exciton dissociation, and charge transport and extraction. As a result, an outstanding fill factor of 77.2% and a promising power conversion efficiency of 17.8 % was achieved. Moreover, the corresponding device shows better thermal stability over the PM6-based one. This work suggests a facile method for significantly improving the thin film morphology of the active-layer materials via fine-tuning the chemical structure of electron-deficient units on the backbone of the wide bandgap donor polymer, therefore achieving enhanced photovoltaic performance and thermal stability for practical applications.
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| 8. |
- Wu, Jingnan, 1994, et al.
(författare)
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New Electron Acceptor with End-Extended Conjugation for High-Performance Polymer Solar Cells
- 2021
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 35:23, s. 19061-19068
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Tidskriftsartikel (refereegranskat)abstract
- To develop high-efficiency polymer solar cells (PSCs), the acceptors in a bulk heterojunction (BHJ) blend are supposed to possess complementary absorption bands in the near-infrared region and a suitable energy level to be well-matched with the donors. In this work, a new small molecular acceptor (SMA) named IDTT8-N based on an indacenodithienothiophene (IDTT) core was designed and synthesized. In comparison to the counterpart molecule IDTN with an indacenodithiophene (IDT) core, IDTT8-N with the extended π-conjugation length of an IDT core not only exhibits a red shift of ca. 35 nm in optical absorption but also has little change on its lowest unoccupied molecular orbital (LUMO) energy level. Therefore, PSCs based on PM6:IDTT8-N exhibit a superior short-circuit current density (Jsc) and high open-circuit voltage (Voc). Moreover, apart from the strong face-on molecular stacking, distinct end-group π-πstacking of IDTT8-N can be observed in the blends, facilitating the charge transport. Therefore, the optimized PM6:IDTT8-N-based devices exhibit dramatically high and balanced electron mobility (μe) and hole mobility (μh), whose magnitudes are over 10-3 cm2 V-1 s-1. Consequently, an extraordinary PCE of 14.1% with a relatively high Jsc of 20.98 mA cm-2 and a Voc of 0.94 V was recorded. To our knowledge, it is the new record among PSCs with a SMA based on 2-(3-oxocyclopentylidene)malononitrile (INCN) as end groups. These results indicate that extending the π-conjugation length of the fused ring core of a SMA is an efficient method to both enhance the absorption and the molecular interaction of the acceptor as well as the photovoltaic performance of PSCs.
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| 9. |
- Xiong, Shaobing, et al.
(författare)
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Engineering of the Back Contact between PCBM and Metal Electrode for Planar Perovskite Solar Cells with Enhanced Efficiency and Stability
- 2019
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Ingår i: Advanced Optical Materials. - : WILEY-V C H VERLAG GMBH. - 2162-7568 .- 2195-1071. ; 7:19
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Tidskriftsartikel (refereegranskat)abstract
- The cathode interface plays a critical role in achieving high-performance fullerene/perovskite planar solar cells. Herein, the simple molecule Isatin and its derivatives are introduced at the back contact [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)/Al as a cathode modification interlayer. It is revealed that the Isatin interlayers facilitate electron transport/extraction and suppress electron recombination, attributed to the formation of negative dipole potential steps and the passivation of the interfacial trap density. The average power conversion efficiencies of the resulting devices are significantly improved by 11% from 17.68% to 19.74%, with an enhancement in all device parameters including short-circuit current, open-circuit voltage, and fill factor. The hysteresis index is found to disappear. In addition, such interlayer enhances device stability under ambient conditions compared to the control devices due to suppression of moisture-induced degradation of the perovskite films. These findings provide a comprehensive understanding of the engineering of the back contact between PCBM and the metal electrode to improve efficiency and stability of perovskite solar cells.
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| 10. |
- Yan, Xin, et al.
(författare)
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Highly efficient ternary solar cells with reduced non-radiative energy loss and enhanced stability via two compatible non-fullerene acceptors
- 2022
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 10:29, s. 15605-15613
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Tidskriftsartikel (refereegranskat)abstract
- A ternary strategy by introducing a third component into a binary host system has been proven to be a simple and promising method to boost the power conversion efficiency (PCE) and stability of organic solar cells (OSCs). Herein, a high efficient ternary OSC is fabricated, wherein, a non-fullerene acceptor, namely MOIT-M, is introduced as a third component into the PM6:BTP-eC9 blend. MOIT-M possesses good complementary absorption spectra and aligned cascade energy levels with the host binary blend, which benefits light harvesting, exciton dissociation, and charge transport. Moreover, MOIT-M exhibits good miscibility with BTP-eC9, forming a well-mixed phase, which improves molecular packing for better charge transport and optimizes ternary blend morphology. Notably, the incorporation of MOIT-M suppresses non-radiative recombination, leading to reduced non-radiative energy losses (Delta E-nr). As a result, the ternary OSC exhibits a significantly increased PCE of 18.5% with a lower Delta E-nr of 0.21 eV in comparison with the control binary PM6:BTP-eC9 device with a PCE of 17.4% and a Delta E-nr of 0.24 eV. In addition, the ternary OSC displays better storage stability compared to the PM6:BTP-eC9 system. This work indicates that a ternary strategy via combining two compatible small molecule acceptors is effective to simultaneously improve the efficiency and stability of OSCs.
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