用平衡相容性和相分离的新策略提高有机太阳电池效率

New Strategy to Balance the Miscibility and Phase Separation to Improve Organic Solar Cells Efficiency

选择了两种具有不同末端基的非富勒烯受体分子3,9-双-[2-甲烯基-(3-1,1-甲烯丙二腈茚酮)-5,5,11,11-四-(4-己基苯基)]-噻吩[3,2-b]并噻吩引达省二噻吩(ITIC)和3,9-双-[2-甲烯基-(3-1,1-甲烯丙二腈-6,7-一氟茚酮)-5,5,11,11-四-(4-己基苯基)]-噻吩[3,2-b]并噻吩引达省二噻吩(IT-2F)作为第三组分,通过一步沉积(O-SD)和分步顺序沉积(T-SD)两种活性层构筑工艺,分别制备了常规的本体异质结(BHJ)和优化的准平面异质结(PPHJ)三元器件.研究发现,本体异质结薄膜中第三组分相容性的差异可以用来调控薄膜相分离形貌;其中,基于IT-2F的三元薄膜活性层相分离明显增大,器件效率由二元器件的12.02%下降至9.25%;而ITIC的三元薄膜相分离形貌无明显改变,器件效率略有提升.值得注意的是,通过T-SD方法均可以获得垂直梯度分布的异质结活性层薄膜,避免了相容性差异对薄膜形貌的影响,相应的准平面异质结器件获得了超过了13%的光电效率.本文工作表明,利用相容性差异以及顺序沉积工艺来调控活性层的相分离形貌是制备高性能有机太阳电池有效策略.

Obtaining superior charge separation and charge extraction efficiency through tuning the gradient separa-tion morphology of the active layer has been the goal of preparing high-performance organic solar cells(OSCs).Here,we selected two non-fullerene acceptors,3,9-bis{2-methylene-[3-(1,1-dicyanomethylene)-indanone]}-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d∶2′,3′-d′]-sindaceno[1,2-b∶5,6-b′]-dithiophene(ITIC)and 3,9-bis(2-methylene-{[3-(1,1-dicyanomethylene)-6,7-fluoro]-indanone})-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d∶2',3'-d']-s-indaceno[1,2-b∶5,6-b']dithiophene(IT-2F),with different end groups as the third component.The conventional bulk-heterojunction(BHJ)and optimized pseudo-planar-heterojunction(PPHJ)ternary OSC devices were prepared by two active layer construction processes,named one-step deposition(O-SD)and distributed sequential deposition(T-SD),respectively.It was found that the difference in the miscibility of the third component Chem.J.Chinese Universities,2023,44(9),20230177 in the bulk-heterojunction films could regulate the phase separation morphology of the films.Among them,the phase separation increased significantly in the ternary films based on IT-2F and its device efficiency decreased to 9.25%compared to 12.02%of the binary device,while the phase separation morphology of the ternary films based on ITIC did not change significantly,the device efficiency increased slightly.It is worth noting that the active layer films with vertical distribution can be obtained by T-SD method,which avoids the effect of miscibility differences on the film morphology,the corresponding PPHJ device achieves an efficiency of over 13%.This work shows that the utilization of miscibility differences and sequential deposition processes to modulate the phase separation morphology of the active layer is an effective strategy for the preparation of high-performance organic solar cells.