Fundamental limit of light trapping in grating structures

TL;DR

This paper rigorously analyzes the fundamental limits of light-trapping in grating structures, revealing that 2D gratings can surpass traditional limits and highlighting the importance of grating profile symmetry for solar cell efficiency.

Contribution

It introduces a comprehensive electromagnetic analysis of light-trapping limits, demonstrating the effects of grating dimensionality and symmetry on absorption enhancement.

Findings

2D gratings outperform 1D gratings in light trapping

The fundamental limit can exceed the 4n^2 bulk limit

Symmetry of the grating profile influences absorption enhancement

Abstract

We use a rigorous electromagnetic approach to analyze the fundamental limit of light-trapping enhancement in grating structures. This limit can exceed the bulk limit of 4n^2, but has significant angular dependency. We explicitly show that 2D gratings provide more enhancement than 1D gratings. We also show the effects of the grating profile's symmetry on the absorption enhancement limit. Numerical simulations are applied to support the theory. Our findings provide general guidance for the design of grating structures for light-trapping solar cells.