Efficient ternary organic solar cells with suppressed nonradiative recombination via B‒N based polymer donor

Organic solar cells (OSCs) have developed rapidly in recent years. However, the energy loss (<i>E</i> _loss) remains a major obstacle to further improving the photovoltaic performance. To address this issue, a ternary strategy has been employed to precisely tune the <i>E</i> _loss and boost the efficiency of OSCs. The B‒N-based polymer donor has been proved to process high <i>E</i>(T₁) and small Δ<i>E</i> _ST characters, which can inhibition of CT state recombination. Herin, B‒N-based polymer donor PBNT-BDD was incorporated into the state-of-the-art PM6:L8-BO binary to construct ternary OSCs. Together with the optimal morphology, the ternary device affords an impressive power conversion efficiency of 18.95% with an improved open-circuit voltage (<i>V</i> _oc), short-circuit density (<i>J</i> _sc), and reduced <i>E</i> _loss in comparison to the binary ones, which is the highest PCE for B‒N materials-based ternary device. This work broadens the selection of guest materials toward realizing the high performance of OSCs.