New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells

TL;DR

This paper introduces a novel design strategy for thin-film solar cells that uses high-index nanostructures and an optimization algorithm to enhance light trapping without electrical degradation, achieving near-record efficiencies.

Contribution

The study proposes a flat active layer design combined with optimized high-index nanostructures, offering improved optical performance while avoiding electrical degradation common in textured layers.

Findings

Efficiency of flat a-Si:H solar cells can be increased close to the highest certified values.

High refractive index (>3) dielectric materials further boost conversion efficiency.

Optimization algorithm effectively identifies light trapping structures for maximum optical benefit.

Abstract

Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350nm-800nm, the conversion efficiency of solar cells can be further enhanced.