Advanced material system for the design of an intermediate band solar cell: type-II CdTe quantum dots in a ZnCdSe matrix

TL;DR

This study investigates CdTe quantum dots in a ZnCdSe matrix, using advanced epitaxy and characterization techniques to optimize materials for high-efficiency intermediate band solar cells.

Contribution

It demonstrates a growth process for CdTe quantum dots in ZnCdSe and analyzes their structural and optical properties for solar cell applications.

Findings

Quantum dots exhibit suitable size and strain for intermediate band formation.

Superlattice structure confirmed by XRD and PL measurements.

Optimized materials show promise for high-efficiency solar cells.

Abstract

We explore CdTe fractional monolayer quantum dots (QDs) in a ZnCdSe host matrix for potential application in an intermediate band solar cell device. Careful consideration has been taken during the initiation of the growth process of QDs by migration enhanced epitaxy, in order to avoid the formation of undesirable interfacial layers that can form due to the lack of common anion between the two materials. A superlattice structure of 100 periods of alternating QD and spacer layers is analyzed by high resolution X-ray diffraction (XRD) and photoluminescent (PL) spectroscopy. Simple arguments are used following continuum elastic theory to deduce the size of the dots and the strain within the superlattice from XRD data. This is further verified using PL and used in the energy calculations that yield the values of the intermediate band energy. The results suggest that the optimized materials are highly suitable for these high efficiency solar cells.