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

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-pi-A'-pi-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.

Automated summary

The rapid development of BDT-centered small molecule donors has led to comparable power conversion efficiencies in ASM-OSCs, but their complexity limits cost performance. Oligothiophene donors, though more accessible, have shown unsatisfactory performance. The novel thiazole-centered oligothiophene donor Tz6T, when combined with a nonfullerene acceptor, achieved a milestone efficiency of 15.4%, pushing oligothiophene to the forefront of small molecule donors.