Toward High‐Performance Semi‐Transparent Polymer Solar Cells: Optimization of Ultra‐Thin Light Absorbing Layer and Transparent Cathode Architecture

High-performance semi-transparent polymer photovoltaic devices (STOPVs) exhibiting both high transparency and superior color rendering properties are demonstrated. The ultra-thin photoactive layer (∼50 nm) possesses similar light absorbing efficiency as the thick case (∼90 nm) after optimization. Highly transparent fullerene surfactant/Ag hybrid cathode is used to enable suitable optical absorption, light transmittance, and effective collection of electrons. The resulting STOPVs exhibit a high power conversion efficiency (5.1%) and high average visible-light transmissivity (25%) with neutral color perception close to white light.