Limit of light coupling strength in solar cells

TL;DR

This paper establishes a fundamental limit on how strongly light can be coupled into solar cell modes, based on the cell's physical and optical properties, aiding in design and efficiency assessment.

Contribution

It introduces a universal coupling strength limit for solar cells that depends on thickness and refractive index, applicable to various resonant devices.

Findings

Maximum coupling rate formula derived: 2c*sqrt(n^2-1)/d

Limit depends on cell thickness and refractive index

Applicable to solar cell design and resonant phenomena

Abstract

We introduce a limit for the strength of coupling light into the modes of solar cells. This limit depends on both a cell's thickness and its modal properties. For a cell with refractive index n and thickness d, we obtain a maximal coupling rate of 2c*sqrt(n^2-1)/d where c is speed of light. Our method can be used in the design of solar cells and in calculating their efficiency limits; besides, it can be applied to a broad variety of resonant phenomena and devices.