Optimizations of GaAs Nanowire Solar Cells

TL;DR

This paper demonstrates that GaAs nanowire solar cells can achieve over 19% efficiency through optimized design and simulation, without additional processing or new materials.

Contribution

The study introduces a coupled optoelectronic simulation model for GaAs NW solar cells, enabling quantum efficiency calculations and identifying design optimizations for improved performance.

Findings

Quantum efficiency calculation for NW solar cells

Optimized NW design increases efficiency to over 19%

Effective photon harnessing through structural modifications

Abstract

The efficiency of GaAs nanowire solar cells can be significantly improved without any new processing steps or material requirements. We report coupled optoelectronic simulations of a GaAs nanowire (NW) solar cell with vertical p-i-n junction and high band gap AlInP passivating shell. Our frequency-dependent model facilitates calculation of quantum efficiency for the first time in NW solar cells. For passivated NWs, we find that short-wavelength photons can be most effectively harnessed by using a thin emitter while long-wavelength photons are best utilized by extending the intrinsic region to the nanowire/substrate interface, and using the substrate as a base. These two easily implemented changes, coupled with the increase of NW height to 3.5 um with realistic surface recombination in the presence of a passivation shell, result in a NW solar cell with greater than 19% efficiency.