Photocurrent efficiency enhancement by space-charge effects in organic solar cells with low charge dissociation probability

Abstract

We numerically investigated space-charge effects in organic solar cells generating photocurrent with a low charge dissociation probability, using a drift-diffusion model with the Onsager-Braun model. In contrast to the knowledge that spacecharge effects decrease the photocurrent efficiency, we found that under certain circumstances, the efficiency can be enhanced by the space-charge effects. It is attributed to the increase of the charge dissociation probability spatially averaged in the active layer. Space-charge effects become more significant when mobilities are unbalanced leading to more enhancement in photocurrent efficiency.