Different Morphology Dependence for Efficient Indoor Organic Photovoltaics: The Role of the Leakage Current and Recombination Losses.

Efficient indoor organic photovoltaics (OPVs) have attracted strong attention for their application in indoor electronic devices. However, the route to optimal photoactive film morphology toward high-performance indoor devices has remained obscure. The leakage current dominated by morphology exerts distinguishing influence on the performance under different illuminations. We have demonstrated that morphology reoptimization plays an important role in indoor OPVs, and their optimal structural features are different from what we laid out for outdoor devices. For indoor OPVs, in order to facilitate low leakage current, it is essential to enhance the crystallinity, phase separation, and domain purity, as well as keeping small surface roughness of the active layer. Furthermore, considering the reduced bimolecular recombination at low light intensity, we have shown that PM6:M36-based indoor devices can work effectively with a large ratio of the donor and acceptor. Our work correlating structure-performance relation and the route to optimal morphology outlines the control over device leakage current and recombination losses boosting the progress of efficient indoor OPVs.