THREE-TERMINAL MULTILAYER GAAS-ALGAAS CASCADE CELLS WITH SELECTIVE ELECTRODES.

Radiation induced degradation causes severe current mismatch losses in series cascade cells, resulting in low end-of-life efficiencies. In view of the difficulties with series cascade approaches, a two-bandgap, three-terminal AlGaAs cell is proposed which exploits the feature of selective electrodes (previously proposed by the authors for single-gap multilayer cells) to solve the interconnection problem. This scheme also allows incorporation of additional layers which can improve spectral response and radiation tolerance by reducing bulk recombination losses. A detailed computer model for multilayer, multi-bandgap photovoltaics has been developed to assess their performance potential. Closed-form expressions are used, permitting rapid optimization of layer thicknesses.