Efficient light-trapping in ultrathin GaAs solar cells using quasi-random photonic crystals

TL;DR

This paper demonstrates an ultrathin GaAs solar cell with quasi-random photonic crystals that significantly improve light-trapping, achieving over 22% efficiency with robust performance under various conditions.

Contribution

The study introduces a novel fabrication of quasi-random photonic crystals for ultrathin GaAs solar cells, enhancing light-trapping efficiency and robustness.

Findings

Achieved 22.35% efficiency in 260 nm thick GaAs cell.

Demonstrated effective light-trapping with quasi-random photonic crystals.

Validated robustness under angle and thickness variations.

Abstract

Ultrathin solar cells reduce material usage and allow the use of lower-quality materials thanks to their one order of magnitude smaller thickness than their conventional counterparts. However, efficient photonic light-trapping is required to harvest the incident light efficiently for an otherwise insufficient absorber thickness. Quasi-random photonic crystals are predicted to have high efficient light-trapping while being more robust under angle and thickness variations than simple photonic crystals. Here we experimentally demonstrate a light-trapping solution based on quasi-random photonic crystals fabricated by polymer blend lithography. We control the average lattice parameter by modifying the spin-coating speed. We demonstrate an ultrathin GaAs cell of 260 nm with a rear quasi-random pattern with submicron features, and a Jsc =26.4 mA/cm2 and an efficiency of 22.35% under the global solar spectrum.