Suppression of Edge Recombination in InAs/InGaAs DWELL Solar Cells

TL;DR

This study demonstrates that InAs/InGaAs DWELL solar cells suppress edge recombination effects, maintaining higher efficiency and open-circuit voltage in smaller cells compared to control GaAs cells without DWELL structures.

Contribution

The paper introduces InAs/InGaAs DWELL structures that effectively suppress edge recombination, improving performance in small-scale solar cells.

Findings

DWELL cells show higher short-circuit current density.

DWELL cells maintain stable open-circuit voltage with size reduction.

Edge recombination significantly impacts GaAs control cells.

Abstract

The InAs/InGaAs DWELL solar cell grown by MBE is a standard pin diode structure with six layers of InAs QDs embedded in InGaAs quantum wells placed within a 200-nm intrinsic GaAs region. The GaAs control wafer consists of the same pin configuration but without the DWELL structure. The typical DWELL solar cell exhibits higher short current density while maintaining nearly the same open-circuit voltage for different scales, and the advantage of higher short current density is more obvious in the smaller cells. In contrast, the smaller size cells, which have a higher perimeter to area ratio, make edge recombination current dominant in the GaAs control cells, and thus their open circuit voltage and efficiency severely degrade. The open-circuit voltage and efficiency under AM1.5G of the GaAs control cell decrease from 0.914V and 8.85% to 0.834V and 7.41%, respectively, as the size shrinks from 5*5mm2 to 2*2mm2, compared to the increase from 0.665V and 7.04% to 0.675V and 8.17%, respectively, in the DWELL solar cells.