Lateral oxygen diffusion dominated extrinsic degradation of small molecular organic solar cells

Organic solar cells (OSCs) generally degrade seriously due to the rapid intake of oxygen and water if exposed to the air. In this paper, we investigated the extrinsic degradation of OSCs by showing the remarkable acceleration effect of fluorescent lamps. We attributed this effect to the accelerated lateral diffusion of oxygen in the fullerene layer under light. We simulated the dynamics of this process using a finite-element method. The simulation suggests that the diffusion constant of oxygen in cells increases approximately sevenfold under fluorescent lamps. We finally reported a recovering phenomenon of an unencapsulated OSC in dark, which demands more investigations.

► Irradiations from fluorescent lamps accelerated the degradation of OSCs.
► Diffusion simulations agreed with the observed degradation under different light conditions.
► Fluorescent lamps increased the diffusion constant of oxygen in OSCs sevenfold by fitting.
► Reversible degradation of unencapsulated OSCs was also observed.