基于芳环取代酰亚胺端基的非富勒烯受体材料的合成与光伏性能

Synthesis and Photovoltaic Properties of Non-fullerene Acceptors Based on Aryl-substituted Imide End Groups

端基结构对于有机太阳能电池(OSCs)中非富勒烯受体(NFAs)的光电性能具有重要影响.本文设计合成了3种新型芳环取代的酰亚胺结构的端基(IIC-Ph, IIC-PhBr和IIC-Ph2F),并将其用于制备受体-给体(受体)给体-受体(A-DA′D-A)型NFAs(BTP-IIC-Ph, BTP-IIC-PhBr和BTP-IIC-Ph2F).紫外-可见-近红外吸收光谱对比和理论模拟结果表明,相比于IIC-Ph端基, IIC-PhBr和IIC-Ph2F端基具有更强的吸电子能力,增强了NFAs的分子内电荷转移效应(ICT),促使了吸收红移.端基苯环上强吸电子的溴原子和氟原子的引入,降低了A-DA′D-A型受体的前线轨道能级.基于BTP-IIC-Ph, BTP-IIC-PhBr和BTP-IIC-Ph2F的二元电池分别获得了13.54%, 11.84%和11.58%的能量转换效率(PCEs).相比于BTP-IIC-PhBr和BTP-IIC-Ph2F,基于BTP-IIC-Ph的电池表现出更好的光伏性能,这主要归因于其较高的最低未占有轨道能级(LUMO)所导致的较高开路电压(VOC),以及更好的激子解离能力和更弱的陷阱辅助载流子复合.

The structure of end-group is of great significance for the photovoltaic properties of non-fullerene receptors(NFAs)in organic solar cells.We designed and synthesized three novel end groups with aryl-substituted imide structures(IIC-Ph,IIC-PhBr and IIC-Ph2F)and further prepared three NFAs with acceptor-donor(acceptor)Chem.J.Chinese Universities,2023,44(9),20230182 donor-acceptor(A-DA'D-A)structure(BTP-IIC-Ph,BTP-IIC-PhBr and BTP-IIC-Ph2F).The comparison of UV-Vis-NIR absorption spectra and theoretical simulation showed that IIC-PhBr and IIC-Ph2F had stronger electron-with-drawing ability than IIC-Ph,which enhanced the intramolecular charge transfer effect of NFAs and red-shift their absorption spectra.The introduction of electron-withdrawing Br and F atoms on the terminal benzene rings of accep-tors lowered the frontier molecular orbital energy levels of BTP-IIC-PhBr and BTP-IIC-Ph2F.The power conversion efficiency(PCEs)of solar cell devices based on BTP-IIC-Ph,BTP-IIC-PhBr and BTP-IIC-Ph2F are 13.54%,11.84%,and 11.58%,respectively.Comparison to BTP-IIC-PhBr and BTP-IIC-Ph2F,BTP-IIC-Ph based devices show higher PCE,which can be attributed to the higher open-circuit voltage(VOC)due to its higher LUMO level,better exciton dissociation and less trap assisted carrier recombination.