Dominant Effect of UV-Light-Induced "Burn-in" Degradation in Non-Fullerene Acceptor Based Organic Solar Cells

Rapid degradation of bulk heterojunction (BHJ) organic solar cells employing non-fullerene acceptor molecules, especially during the initial period of operation ("burn-in"), poses a major challenge. Among the prominent factors causing rapid deterioration of device performance, such as light and thermal stress, UV-induced degradation is shown to significantly reduce the lifetime. It is observed that UV-exposed devices exhibit the sharpest decrease in the performance parameters during the burn-in period. Systematic monitoring of solar cell parameters under accelerated aging conditions reveals that the bulk and interfacial charge transport barriers are substantially affected by UV. These trends were observed even in the absence of residual solvent additive DIO (1,8-diiodooctane) in the devices, indicating the intrinsic tendency of the BHJ system to become modified.