Nonradiative recombination loss (qΔVocnonrad), 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-T1, and a nonfullerene acceptor FOIC are reported. When blended with FOIC, the PBDTm-T1-based device yielded a smallest qΔVocnonrad of 0.197 eV, but with a moderate PCE of 3.3%. In contrast, the PTB7-Th:FOIC device exhibited a relatively higher qΔVocnonrad of 0.329 eV; however, a high PCE of 11.9% was found. This trade-off relationship has been resolved using a ternary blend. By incorporation of 20% PBDTm-T1 into the PTB7-Th:FOIC blend, a small qΔVocnonrad value of 0.271 eV and a significantly high PCE of 13.8% were simultaneously obtained. The results demonstrate that the nonradiative recombination loss can be effectively reduced by using a ternary strategy.
We synthesized three fluorinated non-fullerene acceptors, BTP-F, Y6-F and L8-BO-F, and further used them as the third components to fabricate ternary organic solar cells. The PM6:BTP-eC9:BTP-F ternary device yielded a high efficiency of 18.45%.
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