A computational approach to the analysis of distributed Bragg reflectors in direct-gap solar cells

In this paper, the development of a detailed numerical model for analyzing direct-gap solar cells employing distributed Bragg reflectors is described. Energy-dependent reflection coefficients are computed for calculating trapping of external photons, and angular-dependent reflection is considered for trapping of photons emitted via radiative recombination. The resulting numerical model provides the ability to consider in detail the benefits and tradeoffs that arise from variations in the base thickness, base mobility and lifetime, and the distributed Bragg reflector structure itself. Example solar cell structures that may be modeled include AlGaAs/GaAs devices both on GaAs and on Si substrates, as well as novel types of GaSb-based thermophotovoltaic devices.