Compromising Charge Generation and Recombination of Organic Photovoltaics with Mixed Diluents Strategy for Certified 19.4% Efficiency.

The ternary blend has been demonstrated an effective strategy to promote the device performance of organic photovoltaics (OPV) due to the dilution effect. While the compromise between the charge generation and recombination remains a challenge. Here, we proposed a mixed diluents strategy for further improving the device efficiency of OPV. Specifically, the high-performance OPV system with a polymer donor, i.e., PM6, and a non-fullerene acceptor (NFA), i.e., BTP-eC9, is diluted by the mixed diluents, which involve a high band gap NFA of BTP-S17 and a low band gap NFA of BTP-S16 (similar with that of the BTP-eC9). The BTP-S17 of better miscibility with BTP-eC9 can dramatically enhance the open-circuit voltage (V OC ), while the BTP-S16 maximizes the charge generation or the short-circuit current density (J SC ). The interplay of BTP-17 and BTP-S16 enables better compromise between charge generation and recombination, thus leading to a high device performance of 19.76% (certified 19.41%), which is the best among single-junction OPVs. Further analysis on carrier dynamics validates the efficacy of mixed diluents for balancing charge generation and recombination, which can be further attributed to the more diverse energetic landscapes and improved morphology. Therefore, this work provides an effective strategy for high-performance OPV for further commercialization. This article is protected by copyright. All rights reserved.