Investigation into the optical characteristics of the top-illuminated organic solar cells with graphene electrode

Abstract

Optical modeling based on transfer matrix method is employed to investigate optical performance of the top-illuminated organic solar cells (OSCs) with graphene electrode. For the graphene-based OSCs with thin active layer，the upper limit to short-circuit current density () is improved when compared with that of the indium tin oxide-based devices. This is attributed to the zero-order optical resonance of the weak microcavity (WMC) constructed within the devices. But for the devices with relatively thicker active layer, is reduced by the off-resonance suppression of the WMC structure. By capping a WO3 layer on the graphene electrode to tune the WMC structure, the off-resonance suppression can be eliminated and for the graphene-based OSCs is significantly raised due to the combined effects of the first-order and other higher order optical resonance of the WMC. In addition, the capping layer can be used to improve for the top-illuminated OSCs with various organic materials as the active layer. Finally, it is demonstrated that for the graphene-based OSCs with a WMC structure decreases according to Lambert’s cosine law when the incident angle increases.