Photonic assisted light trapping integrated in ultrathin crystalline silicon solar cells by nanoimprint lithography

TL;DR

This paper demonstrates the fabrication of nanoimprinted photonic nanostructures integrated into ultrathin silicon solar cells, significantly improving light absorption and energy efficiency through combined index grading and diffraction effects.

Contribution

It introduces a novel nanoimprint lithography process for integrating photonic nanostructures into ultrathin silicon solar cells, enhancing light trapping and efficiency.

Findings

23% increase in short-circuit current

Enhanced light absorption due to nanopatterning

Improved energy-conversion efficiency

Abstract

We report on the fabrication of two-dimensional periodic photonic nanostructures by nanoimprint lithography and dry etching, and their integration into a 1-{\mu}m-thin mono-crystalline silicon solar cell. Thanks to the periodic nanopatterning, a better in-coupling and trapping of light is achieved, resulting in an absorption enhancement. The proposed light trapping mechanism can be explained as the superposition of a graded index effect and of the diffraction of light inside the photoactive layer. The absorption enhancement is translated into a 23% increase in short-circuit current, as compared to the benchmark cell, resulting in an increase in energy-conversion efficiency.