Sinusoidal nanotextures for light management in silicon thin-film solar cells

Abstract

a Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 µm thin liquid phase crystallized silicon thinfilm solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass.

On Accurate Simulations of Thin-Film Solar Cells With a Thick Glass Superstrate

“…The experimental samples were prepared using a solid-phase crystallisation process, as described in Ref. [5]. The first-order correction resembles the experimental data much better than the zeroth-order correction.…”

Imprinted Nanostructures for Light Management in Crystalline Silicon Thin-Film Solar Cells on Glass

“…Finally, a 10 nm thin silicon oxide layer is sputtered on all three nanostructure types (1)-(3), serving as a passivation layer at the interface to the silicon absorber. More details can be found in references [4,5]. Silicon layers of 8-10 µm thickness are deposited onto these nanostructured superstrates by electron-beam evaporation at a temperature of 600°C resulting in nano-crystalline material.…”

Angle-Resolved Reflectivity Analysis of Textured Substrates for Liquid-Phase Crystallized Silicon Thin-Film Solar Cells

“…However, the electronic material quality can be reduced by introducing nano-structures at this interface [2]. Two approaches were recently introduced that combine high electronic material quality LPC silicon with nanostructures, namely the sinusoidal structure [3] and the smooth anti-reflective three-dimensional (SMART) texture [4]. In this contribution, we investigate the angular dependence of the anti-reflective properties of these two structured LPC silicon absorbers compared to an optimized planar reference sample.…”