Optimized Broadband, Wide-Angle Distributed Bragg Reflectors for Photovoltaics

An important metric in increasing the efficiency of photovoltaic cells, and in particular intermediate band solar cells (IBSC), is the absorption efficiency in the active layer. Distributed Bragg reflectors (DBR) on one or both ends of the active layer are an attractive choice to recycle photons and increase absorption efficiency. However, traditional DBR's operate at single wavelength and incident angle. We apply optimization techniques for the inverse design of broadband and wide-angle DBR's operating at a desired spectral range, with thicknesses that vary with each layer. The optimization is applied to a type-II quantum dot IBSC, taking into consideration the strain for the choice of materials.