Double-absorber thin-film solar cell with 34% efficiency

TL;DR

This paper proposes a double-absorber thin-film solar cell with graded bandgaps, achieving a predicted efficiency of 34.45% through detailed modeling, which surpasses typical single-absorber thin-film efficiencies.

Contribution

It introduces a novel double-absorber design with bandgap grading, significantly improving efficiency predictions for thin-film solar cells.

Findings

Predicted efficiency of 34.45% with optimized bandgap grading.

Use of 300-nm CIGS and 870-nm CZTSSe layers.

Bandgap grading is critical for maximizing efficiency.

Abstract

Power-conversion efficiency is a critical factor for the wider adoption of solar-cell modules. Thin-film solar cells are cheap and easy to manufacture, but their efficiencies are low compared to crystalline-silicon solar cells and need to be improved. A thin-film solar cell with two absorber layers (instead of only one), with bandgap energy graded in both, can capture solar photons in a wider spectral range. With a 300-nm-thick CIGS~absorber layer and an 870-nm-thick CZTSSe~absorber layer, an efficiency of $34.45\%$ is predicted by a detailed optoelectronic model, provided that the grading of bandgap energy is optimal in both absorber layers.