Issue 3, 2012

Ultra-high stacks of InGaAs/GaAs quantum dots for high efficiency solar cells

Abstract

We report ultra-high stacked InGaAs/GaAs quantum dot (QD) solar cells fabricated by the intermittent deposition of In0.4Ga0.6As under an As2 source using molecular beam epitaxy. We obtain a 400-stack In0.4Ga0.6As QD structure without using a strain balancing technique, in which the total number of QDs reaches 2 × 1013 cm−2. Photoluminescence and cross-sectional scanning transmission electron microscope measurements indicate that the In0.4Ga0.6As QD structure exhibits no degradation in crystal quality, no dislocations and no crystal defects even after the stacking of 400 QD layers. The external quantum efficiency and the short-circuit current density of multi-stacked In0.4Ga0.6As QD solar cells increase as the number of stacked layers is increased to 150. Such ultra-high stacks and good cell performance have not been reported for QD solar cells using other material systems. The performance of the ultra-high stacked QD solar cells indicates that InGaAs QDs are suitable for use in high efficiency solar cells requiring thick QD layers for sufficient light absorption.

Graphical abstract: Ultra-high stacks of InGaAs/GaAs quantum dots for high efficiency solar cells

Article information

Article type
Paper
Submitted
10 Jun 2011
Accepted
12 Jan 2012
First published
14 Feb 2012

Energy Environ. Sci., 2012,5, 6233-6237

Ultra-high stacks of InGaAs/GaAs quantum dots for high efficiency solar cells

T. Sugaya, O. Numakami, R. Oshima, S. Furue, H. Komaki, T. Amano, K. Matsubara, Y. Okano and S. Niki, Energy Environ. Sci., 2012, 5, 6233 DOI: 10.1039/C2EE01930B

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