Short circuit current enhancement in GaAs/AlGaAs MQW solar cells

TL;DR

This paper explores methods to improve short circuit current in GaAs/AlGaAs quantum well solar cells through compositional grading and back surface mirroring, supported by experimental data and modeling.

Contribution

It introduces a combined experimental and modeling approach to optimize quantum well solar cells for higher efficiency.

Findings

Back surface mirroring increases optical absorption in the long wavelength range.

Model accurately reproduces quantum efficiency spectra with compositional profiles.

Optimized designs project significant improvements in short circuit current.

Abstract

The GaAs/AlGaAs quantum well solar cell (QWSC) shows promise as a novel approach to higher efficiency solar cells but suffers from a poor short circuit current Jsc. We report on efforts to reduce this problem with the use of compositional grading and back surface mirroring. We present experimental quantum efficiency (QE) data on a range of compositionally graded QWSCs and devices in which the back surface of the cell is coated with a mirror, increasing the optical thickness of the quantum well layer in the long wavelength range. The experimental QE spectra are reproduced by a model which deals with arbitrary compositional profiles and optical cavities formed in the mirrored cells. The model is used to design an optimised QWSC, and projected Jsc values given. Applications including II-VI and tandem solar cells are considered.