Design and Fabrication of PERC-Like CdTe Solar Cells Using Micropatterned Al2O3 Layer

TL;DR

This paper presents the design, fabrication, and characterization of PERC-like CdTe solar cells with patterned Al2O3 passivation layers, aiming to improve Voc while maintaining high Jsc and FF through laser patterning techniques.

Contribution

It introduces a novel laser-beam lithography process for patterning Al2O3 layers on CdTe solar cells, enhancing passivation and device performance.

Findings

Patterned Al2O3 layers improve passivation of CdTe surfaces.

Voc shows different trends compared to Jsc and FF.

Patterning affects the subsurface electronic structure and carrier collection.

Abstract

Recent studies have investigated novel strategies to further improve the limited Voc of CdTe solar cells via increased carrier lifetime and doping density of CdTe thin films. Among various metal oxides, aluminum oxide (Al2O3) is a promising passivation candidate, where the negatively charged Al2O3 layer repels the minority carrier in CdTe and Al2O3 provides a chemically passivating interface, increasing the carrier lifetime. Despite the continuing efforts, an optimized back-contact architecture to improve the Voc while maintaining high Jsc and FF is still under development. In this work, we report the design, fabrication, and characterization of PERC-like CdTe solar cells, where an Al2O3 passivation layer is patterned using laser-beam lithography. Our process enables reproducible patterning on a rough surface CdTe while maintaining the size of the array in the design. Analysis of CdTe PERC devices (As-doped) shows a notably different Voc trend compared to FF and Jsc, independent of the patterned array structures used in this study. The subsurface electronic structure of CdTe and the interplay between carrier selectivity and collection of the patterned Al2O3 could be responsible for the observed PV characteristics.