Simple thiazole-centered oligothiophene donor enables 15.4% efficiency all small molecule organic solar cells

Abstract

Attributed to the rapid development of benzodithiophene (BDT) centered small molecule donors, all small molecule organic solar cells (ASM-OSCs) have achieved comparable power conversion efficiencies (PCEs) (>15%) along with high reproducibility, in contrast to polymer-based OSCs. However, the difficulty and complexity of synthesizing BDT-derived donors limit their cost performance and commercial application. Distinct from the relatively high synthetic complexity that exhibited by most BDT-derived small molecule donors, oligothiophene donors are much more accessible. However, the performance of oligothiophene donors has been unsatisfactory (PCE < 12%). Here, by employing an A–π–A′–π–A structure, a novel thiazole-centered cost-effective oligothiophene donor Tz6T is developed. By incorporating a nonfullerene acceptor eC9-4F, Tz6T based binary ASM-OSCs achieve a milestone efficiency of 15.4% (the certified PCE is 14.8%). This PCE record not only pushes oligothiophene to the forefront of small molecule donors, but also represented one of the crest values achieved by oligothiophene donors.