| 1. |
- Xiao, Manjun, et al.
(författare)
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Approaching 19% efficiency and stable binary polymer solar cells enabled by a solidification strategy of solvent additive
- 2023
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Ingår i: Science in China Series B. - : SCIENCE PRESS. - 1674-7291 .- 1869-1870. ; 66, s. 1500-1510
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Tidskriftsartikel (refereegranskat)abstract
- Additives play a crucial role in enhancing the photovoltaic performance of polymer solar cells (PSCs). However, the typical additives used to optimize blend morphology of PSCs are still high boiling-point solvents, while their trace residues may reduce device stability. Herein, an effective strategy of "solidification of solvent additive (SSA)" has been developed to convert additive from liquid to solid, by introducing a covalent bond into low-cost solvent diphenyl sulfide (DPS) to synthesize solid dibenzothiophene (DBT) in one-step, which achieves optimized morphology thus promoting efficiency and device stability. Owing to the fine planarity and volatilization of DBT, the DBT-processed films achieve ordered molecular crystallinity and suitable phase separation compared to the additive-free or DPS-treated ones. Importantly, the DBT-processed device also possesses improved light absorption, enhanced charge transport, and thus a champion efficiency of 11.9% is achieved in the PM6:Y6-based PSCs with an excellent additive component tolerance, reproducibility, and stability. Additionally, the DBT-processed PM6:L8-BO-based PSCs are further fabricated to study the universality of SSA strategy, offering an impressive efficiency approaching 19% as one of the highest values in binary PSCs. In conclusion, this article developed a promising strategy named SSA to boost efficiency and improve stability of PSCs.
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| 2. |
- Fan, Baobing, et al.
(författare)
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Correlation of Broad Absorption Band with Small Singlet-Triplet Energy Gap in Organic Photovoltaics
- 2023
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773.
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Tidskriftsartikel (refereegranskat)abstract
- Organic photovoltaics (OPV) are one of the most effective ways to harvest renewable solar energy, with the power conversion efficiency (PCE) of the devices soaring above 19% when processed with halogenated solvents. The superior photocurrent of OPV over other emerging photovoltaics offers more opportunities to further improve the efficiency. Tailoring the absorption band of photoactive materials is an effective way to further enhance OPV photocurrent. However, the field has mostly been focusing on improving the near-infrared region photo-response, with the absorption shoulders in short-wavelength region (SWR) usually being neglected. Herein, by developing a series of non-fullerene acceptors (NFAs) with varied side-group conjugations, we observe an enhanced SWR absorption band with increased side-group conjugation length. The underpinning factors of how molecular structures and geometries improve SWR absorption are clearly elucidated through theoretical modelling and crystallography. Moreover, a clear relationship between the enhanced SWR absorption and reduced singlet-triplet energy gap is established, both of which are favorable for the OPV performance and can be tailored by rational structure design of NFAs. Finally, the rationally designed NFA, BO-TTBr, affords a decent PCE of 18.5% when processed with a non-halogenated green solvent.
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| 3. |
- Fan, Baobing, et al.
(författare)
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Correlation of Local Isomerization Induced Lateral and Terminal Torsions with Performance and Stability of Organic Photovoltaics
- 2023
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 145:10, s. 5909-5919
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Tidskriftsartikel (refereegranskat)abstract
- Organic photovoltaics (OPVs) have achieved great progress in recent years due to delicately designed non-fullerene acceptors (NFAs). Compared with tailoring of the aromatic heterocycles on the NFA backbone, the incorporation of conjugated side-groups is a cost-effective way to improve the photoelectrical properties of NFAs. However, the modifications of side-groups also need to consider their effects on device stability since the molecular planarity changes induced by side-groups are related to the NFA aggregation and the evolution of the blend morphology under stresses. Herein, a new class of NFAs with localisomerized conjugated side-groups are developed and the impact of local isomerization on their geometries and device performance/stability are systematically investigated. The device based on one of the isomers with balanced side- and terminal-group torsion angles can deliver an impressive power conversion efficiency (PCE) of 18.5%, with a low energy loss (0.528 V) and an excellent photo- and thermal stability. A similar approach can also be applied to another polymer donor to achieve an even higher PCE of 18.8%, which is among the highest efficiencies obtained for binary OPVs. This work demonstrates the effectiveness of applying local isomerization to fine-tune the side-group steric effect and non-covalent interactions between side-group and backbone, therefore improving both photovoltaic performance and stability of fused ring NFA-based OPVs.
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