| 1. |
- Cai, Yunhao, et al.
(författare)
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Effect of the Energy Offset on the Charge Dynamics in Nonfullerene Organic Solar Cells
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 12:39, s. 43984-43991
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Tidskriftsartikel (refereegranskat)abstract
- The energy offset, considered as the driving force for charge transfer between organic molecules, has significant effects on both charge separation and charge recombination in organic solar cells. Herein, we designed material systems with gradually shifting energy offsets, including both positive and negative values. Time-resolved spectroscopy was used to monitor the charge dynamics within the bulk heterojunction. It is striking to find that there is still charge transfer and charge generation when the energy offset reached -0.10 eV (ultraviolet photoelectron spectroscopy data). This work not only indicates the feasibility of the free carrier generation and the following charge separation under the condition of a negative offset but also elucidates the relationship between the charge transfer and the energy offset in the case of polymer chlorination.
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| 2. |
- Li, Danqin, et al.
(författare)
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Enhanced and Balanced Charge Transport Boosting Ternary Solar Cells Over 17% Efficiency
- 2020
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32:34
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Tidskriftsartikel (refereegranskat)abstract
- Ternary architecture is one of the most effective strategies to boost the power conversion efficiency (PCE) of organic solar cells (OSCs). Here, an OSC with a ternary architecture featuring a highly crystalline molecular donor DRTB-T-C4 as a third component to the host binary system consisting of a polymer donor PM6 and a nonfullerene acceptor Y6 is reported. The third component is used to achieve enhanced and balanced charge transport, contributing to an improved fill factor (FF) of 0.813 and yielding an impressive PCE of 17.13%. The heterojunctions are designed using so-called pinning energies to promote exciton separation and reduce recombination loss. In addition, the preferential location of DRTB-T-C4 at the interface between PM6 and Y6 plays an important role in optimizing the morphology of the active layer.
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| 3. |
- Xiao, Wei, et al.
(författare)
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Exploring Red, Green, and Blue Light-Activated Degradation of Perovskite Films and Solar Cells for Near Space Applications
- 2020
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Ingår i: Solar RRL. - : Wiley-VCH Verlagsgesellschaft. - 2367-198X. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid perovskite solar cells with a high specific power have great potential to become promising power sources mounted on spacecrafts in space applications. However, there is a lack of study on their photostability as light absorbers in those conditions. Herein, the stability of the perovskite films and solar cells under red, green, and blue (RGB) light illumination in medium vacuum that belongs to near space is explored. The perovskite active layers exhibit different degradations from morphological, chemical, and structural points of view. This is attributed to the strong coupling between photoexcited carriers and the crystal lattice and the diversity of RGB light absorption in the perovskite films. Device characterizations reveal that the efficiency loss of perovskite solar cells results from not only perovskite degradation, but also the photoexcited carriers reducing the energy barrier of ion migration and accelerating the migration to generate more deep-level trap defects. Moreover, comparative devices suggest that the well encapsulation can weaken the effect of vacuum on stability.
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| 4. |
- Xiong, Shaobing, et al.
(författare)
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Defect-Passivation Using Organic Dyes for Enhanced Efficiency and Stability of Perovskite Solar Cells
- 2020
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Ingår i: Solar RRL. - : WILEY-V C H VERLAG GMBH. - 2367-198X. ; 4:5
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite solar cells are a highly competitive candidate for next-generation photovoltaic technology. Defects in the perovskite grain boundaries and on the film surfaces however have significant impacts on both the device efficiency and environmental stability. Herein, a strategy using organic dyes as additives to passivate the defect states and produce more n-type perovskite films, thereby improving charge transport and decreasing charge recombination, is reported. Based on this strategy, the power conversion efficiency of the perovskite solar cell is significantly increased from 18.13% to 20.18% with a negligible hysteresis. Furthermore, the rich hydrogen bonds and carbonyl structures in the organic dye can significantly enhance device stability both in terms of humidity and thermal stress. The results present a promising pathway using abundant and colorful organic dyes as additives to achieve high-performance perovskite solar cells.
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| 5. |
- Yang, Jianming, et al.
(författare)
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Energetics and Energy Loss in 2D Ruddlesden-Popper Perovskite Solar Cells
- 2020
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Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 10:23
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Tidskriftsartikel (refereegranskat)abstract
- 2D Ruddlesden-Popper perovskites (RPPs) are emerging as potential challengers to their 3D counterpart due to superior stability and competitive efficiency. However, the fundamental questions on energetics of the 2D RPPs are not well understood. Here, the energetics at (PEA)(2)(MA)(n)-1PbnI3n+1/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) interfaces with varying n values of 1, 3, 5, 40, and infinity are systematically investigated. It is found that n-n junctions form at the 2D RPP interfaces (n = 3, 5, and 40), instead of p-n junctions in the pure 2D and 3D scenarios (n = 1 and infinity). The potential gradient across phenethylammonium iodide ligands that significantly decreases surface work function, promotes separation of the photogenerated charge carriers with electron transferring from perovskite crystal to ligand at the interface, reducing charge recombination, which contributes to the smallest energy loss and the highest open-circuit voltage (V-oc) in the perovskite solar cells (PSCs) based on the 2D RPP (n = 5)/PCBM. The mechanism is further verified by inserting a thin 2D RPP capping layer between pure 3D perovskite and PCBM in PSCs, causing the V-oc to evidently increase by 94 mV. Capacitance-voltage measurements with Mott-Schottky analysis demonstrate that such V-oc improvement is attributed to the enhanced potential at the interface.
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