Role of Nonfullerene Acceptor Impurities and Purification on the Efficiency and Stability of Organic Photovoltaics

The introduction of nonfullerene acceptors (NFAs) has pushed the power conversion efficiency and organic photovoltaics (OPV) device stability to new standards. In this aspect, removal trace impurities from one purification stage next is frequently stressed throughout synthesis photoactive OPV materials NFAs obtain highest-purity material. However, detailed studies effect on performance are less reported. Herein, role NFA optoelectronic characteristics lifetime resulting devices studied. optimization PBDB-T:ITIC-X devices, with various ITIC purity levels (X), been thoroughly studied via a combination photophysical, chemical, morphological, electrical, optical characterization techniques, shine light these lifetime. findings suggest that, even in larger concentrations impurities, careful tuning can produce high efficiencies. Interestingly, less-pure lead longer lifetimes along an enhancement accumulative generation by factor 3, compared purest ITIC-based devices. This demonstrates that selecting material highest may not always be best option for any positive effects must carefully considered both stability.