Ternary Organic Solar Cells with Small Non-Radiative Recombination Loss

Non-radiative recombination loss (" q∆" "V" _"oc" ^"non-rad" ), as a large component of energy loss (Eloss), has become an important factor that limits the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, high-performance ternary OSCs based on a polymer donor PTB7-Th, a polymer donor PBDTm-T1and a non-fullerene acceptor FOIC were reported. When blended with FOIC, the PBDTm-T1-based device yielded a smallest "q∆" "V" _"oc" ^"non-rad" of 0.197 eV, but with a moderate PCE of 3.3%. In contrast, PTB7-Th:FOIC device exhibited a relatively higher "q∆" "V" _"oc" ^"non-rad" of 0.329 eV, however, with a high PCE of 11.9%. This trade-off relationship has been resolved using a ternary blend. By incorporating 20% PBDTm-T1 into the PTB7-Th:FOIC blend, a small "q∆" "V" _"oc" ^"non-rad" value of 0.271 eV and a significantly high PCE of 13.8% were simultaneously obtained. The results demonstrate that the non-radiative recombination loss can be effectively reduced by using a ternary strategy.