Sulfur vs.tellurium: the heteroatom effects on the nonfullerene acceptors

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2019,（7）
• 页码范围: 897-903
• 页数: 7页
• 语种: 英文

摘要

The effect of chalcogen heteroatom variation on donor materials has been systematically investigated.However,this effect on acceptors has rarely been explored.Herein,nonfullerene acceptors BFPSP and BFPTP were reported by simply changing the chalcogen atoms from S to Te.The differences between BFPSP and BFPTP in light absorption,energy levels,excited-state lifetimes,energy loss,charge mobilities,morphology,and photovoltaic properties were systematically investigated to understand the heteroatom effects.More importantly,the electroluminescence spectra,external quantum efficiency of photovoltaics and TD-DFT calculations revealed that the triplet excited state (T11) in energy of BFPTP equals to the charge transfer (CT) state in PBDB-T:BFPTP,which allows T1 excitons,generated by intersystem crossing,to split into free charges to contribute to the efficiency.This contribution provides a strategy for tuning the photophysical properties of nonfullerene acceptors and designing high performance triplet materials for OSCs.