Resonant absorption in multilayer quantum-well and quantum-dot solar cells

TL;DR

This paper presents a theoretical and experimental study on how the position of quantum layers in multilayer quantum-well and quantum-dot solar cells affects resonant light absorption, revealing optimal configurations that significantly enhance absorption and device performance.

Contribution

It introduces a theoretical framework to optimize quantum layer positioning for resonant absorption, supported by numerical simulations and experimental validation.

Findings

Layer position critically influences absorption enhancement.

Optimal placement can double absorption compared to average.

Experimental results confirm theoretical predictions.

Abstract

Epitaxially-grown quantum well and quantum dot solar cells suffer from weak light absorption, strongly limiting their performance. Light trapping based on optical resonances is particularly relevant for such devices to increase light absorption and thereby current generation. Compared to homogeneous media, the position of the quantum layers within the device is an additional parameter that can strongly influence resonant absorption. However, this effect has so far received little attention from the photovoltaic community. In this work, we develop a theoretical framework to evaluate and optimize resonant light absorption in a thin slab with multiple quantum layers. Using numerical simulations, we show that the position of the layers can make the difference between strong absorption enhancement and completely suppressed absorption, and that an optimal position leads to an absorption enhancement twice larger than average. We confirm these results experimentally by measuring the absorption enhancement from photoluminescence spectra in InAs/GaAs quantum dot samples. Overall, this work provides an additional degree of freedom to substantially improve absorption, encouraging the development of quantum wells and quantum dots-based devices such as intermediate-band solar cells.