Highly efficient color-control technique for building-integrated photovoltaics using optical dielectric thin film

Abstract

A color-control technique based on optical thin films on glass is investigated by means of numerical simulation and experiment, with a particular focus on building-integrated photovoltaic (BIPV) applications. We show that white-colored BIPV modules can be realized with a minimum optical loss by applying optical thin films that have multiple reflection peaks in a complementary color relationship, like the emission spectrum of white LEDs. The angular dependence of hue, which is an inherent drawback of optical thin film systems, is suppressed by modifying the design of the film to maintain the complementary color relationship of multiple reflection peaks. The simulated thin film design is confirmed by an experiment with a silicon solar cell, resulting in a white color and a low short-circuit current density loss (ΔJ SC) of 5.9%. These results indicate that our approach is a promising way to realize fascinating colors and a high energy yield simultaneously in BIPV modules.