Integration of a 2D Periodic Nanopattern Into Thin Film Polycrystalline Silicon Solar Cells by Nanoimprint Lithography

TL;DR

This study demonstrates that integrating 2D nanopatterns into polycrystalline silicon solar cells via nanoimprint lithography enhances light absorption and short circuit current, but also increases series resistance, limiting efficiency gains.

Contribution

It introduces a novel method of nanopattern integration into poly-Si solar cells and analyzes its effects on optical and electrical performance.

Findings

Light absorption increased by 6%

Short circuit current improved from 20.6 to 23.8 mA/cm2

Efficiency increased marginally from 6.4% to 6.7%

Abstract

The integration of two-dimensional (2D) periodic nanopattern defined by nanoimprint lithography and dry etching into aluminum induced crystallization (AIC) based polycrystalline silicon (Poly-Si) thin film solar cells is investigated experimentally. Compared to the unpatterned cell an increase of 6% in the light absorption has been achieved thanks to the nanopattern which, in turn, increased the short circuit current from 20.6 mA/cm2 to 23.8 mA/cm2. The efficiency, on the other hand, has limitedly increased from 6.4% to 6.7%. We show using the transfer length method (TLM) that the surface topography modification caused by the nanopattern has increased the sheet resistance of the antireflection coating (ARC) layer as well as the contact resistance between the ARC layer and the emitter front contacts. This, in turn, resulted in increased series resistance of the nanopatterned cell which has translated into a decreased fill factor, explaining the limited increase in efficiency.