Design of Bragg Reflector in GaInP/GaInAs/Ge Triple-junction Solar Cells for Spectrum Splitting Applications

The use of intermediate distributed Bragg reflectors (DBRs) for spectrum splitting photovoltaics is investigated. Optical models for both commercial lattice-matched (LM) and metamorphic (MM) GaInP/GaInAs/Ge triple-junction solar cells (TJSCs) are developed, in good agreement with measured reflectance. Integrating a suitable DBR structure into a TJSC has the potential to provide the required IR reflectance for spectrum splitting from the LM and MM TJSC to a Si cell. We show that the intermediate DBR approach to spectrum splitting has the advantage of a greatly reduced angle-of-incidence dependence compared to a discrete dielectric filter.