Regulating the morphology of fluorinated non-fullerene acceptor and polymer donor via binary solvent mixture for high efficiency polymer solar cells

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2019,（9）
• 页码范围: 1221-1229
• 页数: 9页
• 语种: 英文

摘要

Fluorinated non-fullerene acceptors (NFAs) usually have planar backbone and a higher tendency to crystallize compared to their non-fluorinated counterparts,which leads to enhanced charge mobility in organic solar cells (OSCs).However,this self-organization behavior may result in excessive phase separation with electron donors and thereby deteriorate device efficiency.Herein,we demonstrate an effective approach to tune the molecular organization of a fluorinated NFA (INPIC-4F),and its phase separation with the donor PBDB-T,by varying the casting solvent.A prolonged film drying time encourages the crystallization of INPIC-4F into spherulites and consequently results in excessive phase separation,leading to a low device power conversion efficiency (PCE) of 8.1％.Contrarily,a drying time leads to fine mixed domains with inefficient charge transport properties,resulting in a moderate device PCE of 11.4％.An intermediate film drying time results in the formation of face-on π-π stacked PBDB-T and INPIC-4F domains with continuous phase-separated networks,which facilitates light absorption,exciton dissociation as well as balanced charge transport towards the electrode,and achieves a remarkable PCE of 13.1％.This work provides a rational guide for optimizing the molecular ordering of NFAs and electron donors for high device efficiency.