Quantifying External Radiative Efficiency in Organic Photovoltaics

External radiative efficiency (ERE) quantifies nonradiative voltage loss in the solar cells. However, the ERE of organic photovoltaics (OPV) is rarely investigated. This paper presents a systematic methodology for calculating ERE and applies it to evaluate high-efficiency OPV devices. Through detailed simulations, we quantify nonradiative voltage loss and compare ERE performance across different OPV technologies and perovskites. Our analysis revealed that non-fullerene acceptor OPVs demonstrate higher ERE than their fullerene-based counterparts, though they still lag behind perovskite solar cells. Further investigation is needed to understand the limitations of ERE in OPV