High-efficiency ternary nonfullerene polymer solar cells with increased phase purity and reduced nonradiative energy loss

In this work, we used a ternary blend strategy to improve the photovoltaic performance of organic solar cells (OSCs). PBDB-T:IDT-EDOT-based binary blend devices show a power conversion efficiency (PCE) of 9.93%, and the ternary devices with PC₇₁BM as the third component exhibit a PCE of 12.07% with simultaneously enhanced V_oc, J_sc and FF. The broadened absorption, optimized morphology and balanced charge carrier mobility of these devices are responsible for these improvements. The introduction of PC₇₁BM can disperse the IDT-EDOT aggregates, enhance the phase purity, and increase the electroluminescence quantum efficiency (EQE_EL). Furthermore, the performance of the ternary devices is not very sensitive to the weight ratio of the two acceptors. PCEs of over 11% are obtained even though the composition gradually varies from 1 : 1 : 0.2 to 1 : 0.4 : 0.8. Our results demonstrate that PC₇₁BM is a highly promising second acceptor for the construction of high-efficiency ternary OSCs.