Polymer Acceptor Copolymerized with Luminescent Unit for High‐Performance All‐Polymer Solar Cells with Low Non‐radiative Energy Loss

Abstract

Reduction of non‐radiative energy loss (ΔEnr) in all‐polymer solar cells (all‐PSCs) is crucially important for achieving high power conversion efficiencies (PCEs). Herein, an efficient strategy is reported to reduce the ΔEnr by introducing luminescent unit into the backbone of polymer acceptors. Compared to the device based on PM6:PYDT, the ΔEnr in all‐PSC based on PM6:PYDT‐CzP‐9 has decreased from 0.188 to 0.183 eV. This reduction is attributed to the improvement in electroluminescence external quantum efficiency (EQEEL). The PM6:PYDT‐CzP‐9 device has shown an 18% increase in EQEEL compared to the device based on PM6:PYDT (8.4 × 10−4 vs 7.1 × 10−4), demonstrating that the incorporation of luminescent unit in polymer acceptors is highly effective in enhancing the electroluminescence performance of all‐PSCs. As a result, the PM6:PYDT‐CzP‐9 device yielded a high VOC of 0.967 V, without the sacrifice of short‐circuit current density (23.42 mA cm−2) and fill factor (77.5%), leading to a high PCE of 17.55%.