Fluorination-substitution effect on all-small-molecule organic solar cells

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2019,（7）
• 页码范围: 837-844
• 页数: 8页
• 语种: 英文

摘要

Due to the strong crystallinity and anisotropy of small molecules,matched molecular photoelectric properties and morphologies between small molecules and non-fullerene acceptors are especially important in all-small-molecule organic solar cells (OSCs).Introducing fluorine atoms has been proved as an effective strategy to achieve a high device performance through tuning molecular energy levels,absorption and assembly properties.Herein,we designed a novel benzodithiophene-based small molecule donor BDTF-CA with deep highest occupied molecular orbital (HOMO) energy level.All-small-molecule OSCs were fabricated by combing non-fullerene acceptor IDIC with different fluorine-atom numbers.Two or four fluorine atoms were introduced to the end-capped acceptor of IDIC,which are named as IDIC-2F and IDIC-4F,respectively.With the increase of fluorination from IDIC to IDIC-4F,the open circuit voltage (Voc) of the devices decreased,while hole and electron mobilities of the active layers increased by one order of magnitude.Contributed to the most balanced Voc,short-circuit current (Jsc) and fill factor (FF),the device based on BDTF-CA/IDIC-2F achieved the highest power conversion efficiency of 9.11％.