Radiative cooling of a GaAs solar cell to improve power conversion efficiency

Many methods have been proposed to improve the power conversion efficiency of a solar cell beyond the Shockley-Queisser limit, e.g. hot carrier extraction, multi-exciton generation, multi-junction, intermediate bands, etc. Such methods rely on breaking various assumptions about the carrier generation or collection in a single-junction device under one sun illumination. Here we challenge an implicit assumption, i.e. that the device is operating at the ambient temperature of the surroundings. Instead, we show that a photonic material can be placed in contact with the solar cell in order to improve thermal emission and hence cool the solar cell. As the solar cell is passively cooled, the efficiency goes up. As an example, we consider a single-junction GaAs solar cell and find that the device with a radiative cooler has a temperature 18 °C less than a typical GaAs solar cell operating at standard operating conditions, yielding improvement in the power conversion efficiency.