Optimization approach for optical absorption in three-dimensional structures including solar cells

TL;DR

This paper presents a coupled RCWA and DEA optimization method to enhance optical absorption in 3D solar cell structures, considering both optical and electrical performance metrics.

Contribution

It introduces a practical optimization framework combining RCWA and DEA for 3D structures, accounting for electrical performance in solar cell design.

Findings

Optimal bandgap of the topmost i-layer is most significant for absorption.

Inclusion of electrical performance metrics leads to different optimal configurations.

The approach is adaptable to various photovoltaic and optical absorber designs.

Abstract

The rigorous coupled-wave approach (RCWA) and the differential evolution algorithm (DEA) were coupled in a practicable approach to maximize absorption in optical structures with three-dimensional morphology. As a model problem, optimal values of four geometric parameters and the bandgaps of three i-layers were found for an amorphous-silicon, multi-terminal, thin-film tandem solar cell comprising three p-i-n junctions with a metallic hexagonally corrugated back-reflector. When the optical short-circuit current density was chosen as the figure of merit to be maximized, only the bandgap of the topmost i-layer was significant and the remaining six parameters played minor roles. While this configuration would absorb light very well, it would have poor electrical performance. This is because the optimization problem allows for the thicknesses and bandgaps of the semiconductor layers to change. We therefore devised another figure of merit that takes into account bandgap changes by estimating the open-circuit voltage. The resulting configuration was found to be optimal with respect to all seven variable parameters. The RCWA+DEA optimization approach is applicable to other types of photovoltaic solar cells as well as optical absorbers, with the choice of the figure of merit being vital to a successful outcome.