Eur. Phys. J. Appl. Phys. 97, 1 (2022)
https://doi.org/10.1051/epjap/2021210215

Regular Article

Micro-concentrated photovoltaics based on Cu(In,Ga)Se₂ microcells: an optical study^★

School of Materials Science and Engineering, Wuhan University of Technology, Luoshi Road 122, 430070 Wuhan, P.R. China

^* e-mail: guanchao.yin@whut.edu.cn

Received: 4 October 2021
Received in final form: 12 November 2021
Accepted: 7 December 2021
Published online: 13 January 2022

Abstract

Micro-concentrated Cu(In,Ga)Se₂ (µCPV-CIGSe) solar cells offer the potential to greatly reduce the consumption of raw materials while maintaining high efficiencies. A theoretical model of µCPV-CIGSe solar cells, consisting of hexagonally spaced micro-CIGSe (µ-CIGSe) solar cells embedded in the low-index dielectric matrix and µ-lenses placed on top, is proposed for optical study. It is discovered that µ-lenses enable to effectively concentrate the incident light due to the inherent nanojet phenomenon, and the µ-CIGSe absorbers trap the penetrated light within absorbers arising from wave-guided modes. The two effects co-contribute to an optimized absorption for µCPV-CIGSe solar cells with a µ-CIGSe absorber diameter of 800 nm and a pitch of 1500 nm. Short-circuit current density reaches 36.5 mA/cm² and accounts for 98.8% compared to their plain counterparts without lenses, corresponding to an absorber material saving by a factor of 3/4. Notably, a large contacting area between lenses and CIGSe solar cells are recommended for an improved angular tolerance. Those findings will recommend design principles for further experiments.