Over 30% Efficient Indoor Organic Photovoltaics Enabled by Morphological Modification Using Two Compatible Non-Fullerene Acceptors

To meet the requirements for indoor organic photovoltaic (OPV) applications, it is imperative to minimize charge recombination loss and enhance photovoltaic performance toward commercially compelling levels. Here, morphological modification in non-fullerene blends is demonstrated to boost the efficiency and stability of indoor OPVs. For morphological modification, a ternary blend is devised by utilizing two well-miscible non-fullerene acceptors, which improve morphological features in the photoactive layer and suppress charge recombination loss. Morphological modification enhances OPV performance, particularly under low-intensity indoor irradiation conditions, at which trap-assisted recombination mainly governs the photovoltaic performance. The optimum ternary OPV shows a new record power conversion efficiency of 30.11% at a 500 lux light-emitting diode, accompanied by excellent morphological durability under thermal stress, despite the use of "existing" photovoltaic materials designed for AM 1.5 G operation. This study elucidates the effects of morphology on OPV performance under low-light conditions and suggests an ideal morphology for non-fullerene OPVs with enhanced performance for indoor applications.