A novel silicon nanostructure with effective light trapping for polycrystalline silicon thin film solar cells by means of metal-assisted wet chemical etching

Abstract

Effective light trapping is required for poly-Si thin film solar cells to compensate for the moderate light absorption. Recent developments of light trapping in the poly-Si cell technology focus on random light scattering in the absorber layer by three means: glass substrate texture, silicon film etch-back texture, and plasmonic nanoparticles. Although silicon nanostructures like porous silicon, silicon nanowires, and silicon nanoholes demonstrate good optical properties, they are seldom considered for poly-Si thin film solar cells due to generally poor electronic properties and difficulty of fabrication. In this paper, the first poly-Si thin film solar cells with a novel silicon nanostructure are fabricated. The Si nanostructure is fabricated by means of metal-assisted wet chemical etching. Silver nanoparticles created by thermal annealing of evaporated silver thin film are used as etching catalyst. Light absorption for both glass-side and air-side illumination are significantly improved. The short-circuit current is enhanced by 21.0% as measured from the glass side and 53.5% from the air side. The open-circuit voltage is improved by 22 mV. It is first demonstration of working poly-Si thin film cells made of such material.