Observation of reversible light degradation in organic photovoltaics induced by long-persistent radicals

Abstract

With the rapid development of organic photovoltaics, device stability has become a crucial obstacle hindering their transition from laboratory-scale to industrial applications. However, it still remains unclear how light differs from heat in driving trap formation and device degradation. On the basis of the PTzBI-dF:Y6-BO system, it is observed that the post-thermal annealing on these high-performance organic solar cells can partially recover the light-induced burn-in losses. The recovery process is found to be correlated with a reversible charge extraction ability, reversible trap density of state, local charge carrier density and charge accumulation. Herein, we propose an innovative mechanism for light degradation in organic photovoltaic devices, which is triggered by the presence of light-induced long-persistent radicals. The findings offer deep insights into light degradation of organic photovoltaics and a new perspective for improving device stability under long-term operation.