Smooth anti-reflective three-dimensional textures for liquid-phase crystallized silicon thin-film solar cells on glass

TL;DR

The paper introduces SMART textures that combine optical and electronic benefits to enhance light absorption and efficiency in liquid-phase crystallized silicon thin-film solar cells, achieving record voltages and increased current density.

Contribution

A novel SMART texture method that reduces reflection without increasing recombination, improving both optical and electronic performance of silicon thin-film solar cells.

Findings

Achieved over 640 mV Voc in 8 μm thick cells.

Increased short-circuit current density by 11%.

Validated improvements through simulations and experiments.

Abstract

Recently, liquid-phase crystallization of thin silicon films has emerged as a promising candidate for thin-film photovoltaics. On 10 \mu m thin absorbers, wafer-equivalent morphologies and open-circuit voltages were reached, leading to a record efficiency of 12.1%. However, short-circuit current densities are still limited, mainly due to optical losses at the glass-silicon interface. While nano-structures at this interface have been shown to efficiently reduce reflection, up to now these textures caused an increase in recombination. Therefore, optical gains were mitigated due to electronic losses. Here, the SMooth Anti-Reflective Three-dimensional (SMART) texture is introduced in order to overcome this trade-off. By smoothing nanoimprinted SiOx nano-pillar arrays with spin-coated TiOx layers, light-trapping properties of laser-crystallized silicon solar cells could significantly be improved as successfully shown in three-dimensional simulations and in experiment. At the same time, the smooth surface morphology of SMART textures allows preserving electronic material quality equivalent to that of planar reference samples and reaching Voc values above 640 mV in 8 \mu m thin liquid-phase crystallized silicon solar cells. Furthermore, the short-circuit current density jsc could be increased from 21.0 mA cm-2 for planar reference cells with already optimized anti-reflective interlayer stacks to 23.3 mA cm-2 on SMART textures, corresponding to a relative increase of 11%.