An optical arrangement for boosting the efficiency of a system containing a GaAs solar cell

GaAs solar cells exceed 28% efficiency under no light concentration, and this is partly due to their near-optimum bandgap of 142 eV. Also, the electrical and optical properties of GaAs enable efficient generation and collection of free carries excited by photons with wavelengths below 870 nm. However, this part of the spectrum represents less than 40% of the total solar spectrum, and the remaining 60% is not utilized. The purpose of this research is to convert this part of the spectrum to enhance the efficiency of the GaAs cell. This is achieved by proposing an optical arrangement that splits the solar spectrum at the wavelength 870 nm, and direct the normally not utilized part of the spectrum towards a single-junction thermophotovoltaic cell. Several medium and low energy bandgap materials are considered, and based on their I-V parameters, the optimal configuration of the proposed optical design is decided. Around 40% improvement in efficiency has been achieved by combining the GaAs cell with an InGaAs cell in the proposed optical arrangement.