Polymer photovoltaic devices with highly transparent cathodes

In this paper, we demonstrate semi-transparent polymer solar cells employing a transparent cathode configuration, made of cesium carbonate (Cs2CO3)/silver (Ag)/indium tin oxide (ITO), which exhibited high transmittance in the visible regime. The device performance of the semi-transparent devices was significantly improved after thermal post-annealing and incorporating an Al counter-electrode (CE) grid. Further, the short-circuit current density increased almost linearly with the incident light intensity, suggesting efficient charge collection ability of the transparent cathode. Overall, the semi-transparent polymer solar cell exhibits a remarkable power conversion efficiency of 2.09%.