Photo-degradation and its recovery by thermal annealing in polymer-based organic solar cells

Organic solar cells (OSCs) have potential advantages in their mechanical flexibility, portability, and low manufacturing cost. The power conversion efficiencies (PCEs) of OSCs based on conjugated polymers and soluble fullerenes have been improved markedly in the recent decade. For practical use, long-term stability of the cell performance, as well as high efficiency is essential. In contrast to considerable efforts on improving the PCE of OSCs, researches on the stability of OSCs had been rarely performed until the last few years so that the degradation mechanism and key technologies for the long-term stability are still unclear. In this study, we investigated the degradation under light irradiation and confirmed the recovery of cell performances by thermal annealing.