Colorful conducting polymers for vivid solar panels

Photovoltaic (PV) panels with vivid colors provide an additional dimension for developing new applications such as aesthetically appealing solar buildings and mobile products. Thus, rendering PV panel colorful at low cost while keeping high power conversion efficiency (PCE) is of great interest to the community. Based on polymer/Si heterojunction test cells, here we report that color rendering can be made by modifying the optical refractive index of the PEDOT:PSS films. The key to achieving the desired refractive index of the PEDOT:PSS layer for a specific color is to select proper doping material. Guided by theoretical modeling analysis, we have developed 1 × 1 cm 2 silicon heterojunction solar cells with colors across the entire visible spectrum while simultaneously achieving a competitive PCE of 13.2%. As a solution-based process is used to fabricate the Si heterojunction cells, the method reported here can be readily scaled up using mature industrial tools such as inkjet printers.