基于一种新型聚噻吩衍生物为给体的非富勒烯聚合物太阳能电池

摘要

With the development of non-fullerene small-molecule acceptors,non-fullerene polymer solar cells (PSCs) have gamered increased attention due to their high performance.While photons are absorbed and converted to free charge carriers in the active layer,the donor and acceptor materials both play a critical role in determining the performance of PSCs.Among the various conjugated-polymer donor materials,polythiophene (PT) derivatives such as poly(3-hexylthiophene),have attracted considerable interest due to their high hole mobility and simple synthesis.However,there are limited studies on the applications of PT derivatives in non-fullerene PSCs.Fabrication of highly efficient non-fullerene PSCs utilizing PT derivatives as the donor is a challenging topic.In this study,a new PT derivative,poly[5,5'-4,4'-bis(2-butyloctylsulphanyl)-2,2'-bithiophene-alt-5,5'-4,4'-difluoro-2,2'-bithiophene] (PBSBT-2F),with alkylthio groups and fluorination was synthesized for use as the donor in non-fullerene PSC applications.The absorption spectra,electrochemical properties,molecular packing,and photovoltaic properties of PBSBT-2F were investigated and compared with those of poly(3-hexylthiophene) (P3HT).The polymer exhibited a wide bandgap of 1.82 eV,a deep highest occupied molecular orbital (HOMO) of-5.02 eV,and an ordered molecular packing structure.Following this observation,PSCs based on a blend of PBSBT-2F as the donor and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno-[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) as the acceptor were fabricated.The absorption spectra were collected and the energy levels were found to be well matched.These devices exhibited a power conversion efficiency (PCE) of 6.7％ with an open-circuit voltage (Voc) of 0.75 V,a short-circuit current density (Jsc)of 13.5 mA·cm-2,and a fill factor (FF) of 66.6％.These properties were superior to those of P3HT (1.2％) under the optimal conditions.This result indicates that PBSBT-2F is a promising donor material for non-fullerene PSCs.%在各种共轭聚合物给体材料中,以聚3-己基噻吩为代表的聚噻吩衍生物因其结构简单、易制备以及良好的空穴传输性能,在富勒烯衍生物为受体材料的聚合物太阳能电池体系中一直是研究重点之一.但是在近年来发展迅速的稠环小分子非富勒烯体系中的相关研究较少.在本工作中,我们通过在噻吩侧链引入烷硫基和氟取代基,设计合成了一种新型的聚噻吩衍生物给体PBSBT-2F:并对其吸收光谱、分子能级、传输性能以及光伏性能进行研究.基于PBSBT-2F:ITIC的聚合物太阳能电池取得6.7％的能量转换效率,其中开路电压为0.75V,短路电流为13.5 mA·cm-2,填充因子为66.6％.结果表明:PBSBT-2F在非富勒烯体系中有很大的应用潜力.