Broadband and omnidirectional anti-reflection layer for III/V multi-junction solar cells

TL;DR

This paper introduces a novel graded refractive index antireflection coating using tapered GaP nanowires for III/V multi-junction solar cells, significantly reducing reflection and increasing photocurrent density.

Contribution

It presents a new nanowire-based graded refractive index coating for solar cells, demonstrating improved optical performance and feasibility of growth on III/V substrates.

Findings

Photocurrent density increased by 5.9% with the coating.

Reflection was reduced and transmission increased across broad spectral and angular ranges.

Successful growth of tapered GaP nanowires on III/V substrates demonstrated.

Abstract

We report a novel graded refractive index antireflection coating for III/V quadruple solar cells based on bottom-up grown tapered GaP nanowires. We have calculated the photocurrent density of an InGaP-GaAs-InGaAsP-InGaAs solar cell with a MgF2/ZnS double layer antireflection coating and with a graded refractive index coating. The photocurrent density can be increased by 5.9 % when the solar cell is coated with a graded refractive index layer with a thickness of 1\mu m. We propose to realize such a graded refractive index layer by growing tapered GaP nanowires on III/V solar cells. For a first demonstration of the feasibility of the growth of tapered nanowires on III/V solar cells, we have grown tapered GaP nanowires on AlInP/GaAs substrates. We show experimentally that the reflection from the nanowire coated substrate is reduced and that the transmission into the substrate is increased for a broad spectral and angular range.