The performance of organic photovoltaics is largely dependent on the balance of short-circuit current density (J_SC) and open-circuit voltage (V_OC). For instance, the reduction of the active materials’ optical bandgap, which increases the J_SC, would inevitably lead to a concomitant reduction in V_OC. Here, we demonstrate that careful tuning of the chemical structure of photoactive materials can enhance both J_SC and V_OC simultaneously. Non-fullerene organic photovoltaics based on a well-matched materials combination exhibit a certified high power conversion efficiency of 12.25% on a device area of 1 cm². By combining Fourier-transform photocurrent spectroscopy and electroluminescence, we show the existence of a low but non-negligible charge transfer state as the possible origin of V_OC loss. This study highlights that the reduction of the bandgap to improve the efficiency requires a careful materials design to minimize non-radiative V_OC losses.

有机光伏电池的性能在很大程度上取决于短路电流密度（J _SC）和开路电压（V _OC）的平衡。例如，降低活性材料的光学带隙会增加J _SC，这不可避免地会导致V _OC的降低。在这里，我们证明了仔细调整光敏材料的化学结构可以同时增强J _SC和V _OC。基于良好匹配的材料组合的非富勒烯有机光伏器件在1 cm ²的器件面积上具有经认证的12.25％的高功率转换效率。通过结合傅里叶变换光电流能谱和电致发光，我们显示出一个低但不可忽略的电荷转移状态的存在，可能是V _OC损失的原因。这项研究强调，降低带隙以提高效率需要精心设计材料，以最大程度地减少无辐射的V _OC损耗。