Efficiency Optimization of Si-nanowire Heterojunction Solar Cell by Band Gap Engineering

Abstract

The Si Nanowire arrays offer a distinct advantage in solar cell design due to the tunable band gap with improved performance. By increasing the SiNW emitter band gap from 1.1 eV to 1.9 eV, the work demonstrates a significant efficiency boost from 15.2% to 21.7% for the optimized band gap of 1.5 eV. An increased open-circuit voltage primarily drives the improvement, as the wider band gap creates a larger valence band offset, which suppresses hole injection and reduces interface recombination. Furthermore, the wider gap enables high-energy photons to reach the absorber more effectively, thereby enhancing photogeneration and potentially allowing these heterojunction cells to outperform traditional Si homojunctions.