The complex structure within the photoactive layer of organic photovoltaics (OPVs) makes it challenging to establish a clear structure-performance relationship. In this study, we investigate the morphological origins of performance limitations in OPVs, with a particular focus on deep-trap-assisted monomolecular recombination. Through advanced morphological and device-physics characterization techniques, we identify isolated crystalline and amorphous acceptor domains as primary sources of deep electron traps, due to the substantial LUMO offset between donor and acceptor materials employed in high-performance OPVs.… Read More