Non-Epitaxial GaAs Heterojunction Nanowire Solar Cells (PVSC)

Abstract

The efficiency of substrate-removed GaAs nanowire solar cells can be increased to over 32% by borrowing processes and materials from GaAs MOSFETs and perovskite photovoltaics. Photogenerated carriers fundamentally limit the performance of off-wafer homojunction devices to less than 15% efficiency by creating low resistance pathways for minority carriers to recombine at ohmic contacts. We report the results of coupled optoelectronic device physics simulations of GaAs nanowire homojunction solar cells and GaAs nanocone heterojunction solar cells where SnO₂ and CuSCN are used for charge carrier collection. Our simulations include realistic recombination models for bulk and surface recombination. We find the optimal design is a radial junction with moderately p-type GaAs. Densities of states previously demonstrated in GaAs MOSFETs enable efficiencies greater than 30%