Liquid phase crystallized silicon on glass: Technology, material quality and back contacted heterojunction solar cells

Abstract

Liquid phase crystallization has emerged as a novel approach to grow large grained polycrystalline silicon films on glass with high electronic quality. In recent years a lot of effort was conducted by different groups to determine and optimize suitable interlayer materials, enhance the crystallographic quality or to improve post crystallization treatments. In this paper, we give an overview on liquid phase crystallization and describe the necessary process steps and discuss their influence on the absorber properties. Available line sources are compared and different interlayer configurations are presented. Furthermore, we present one-dimensional numerical simulations of a rear junction device, considering silicon absorber thicknesses between 1 and 500 µm. We vary the front surface recombination velocity as well as doping density and minority carrier lifetime in the absorber. The simulations suggest that a higher absorber doping density is beneficial for layer thicknesses below 20 µm or when the minority carrier lifetime is short. Finally, we discuss possible routes for device optimization and propose a hybride cell structure to circumvent current limitations in device design.

Influence of the Frontside Charge Inversion Layer on the Minority Carrier Collection in Backside Contacted Liquid Phase Crystallized Silicon on Glass Solar Cells

“…Many methods are being developed to prepare thin crystalline silicon absorber layers (<50 μm) in order to reduce material costs . Liquid phase crystallized silicon (LPC‐Si) on glass consists of a glass substrate, an interlayer stack and a 5–40 μm Si absorber, which is crystallized over a liquid phase by melting a silicon precursor layer with a line shaped energy source . The interlayer stack serves as diffusion barrier, anti‐reflection coating and passivation layer and is usually composed of silicon oxide (SiO x ), silicon nitride (SiN x ), and/or silicon oxynitride (SiO x N y ) layers .…”

Optical simulations of advanced light management for liquid-phase crystallized silicon thin-film solar cells

“…4,5 The LPC process is performed on a nanocrystalline Si layer on an interlayer stack on glass. Light management is used used to (i) reduce the reflective losses of the device via maximizing incoupling of light from the glass superstrate into the c-Si absorber, which has a high refractive index.…”

Fabrication of polycrystalline silicon films by Al‐induced crystallization of silicon‐rich oxide films

“…Polycrystalline silicon (poly‐Si) thin films have received considerable attention because of their great potential for advanced electronic and photovoltaic applications . In particular, they are now drawing attention as a promising alternative for solar cells that exhibit both high conversion efficiency and low production costs; consequently considerable research efforts have been devoted to the fabrication of high‐quality poly‐Si films with electrical properties that are suitable for low‐cost photovoltaic applications.…”