Triple-junction solar cells with 39.5% terrestrial and 34.2% space efficiency enabled by thick quantum well superlattices

TL;DR

This paper demonstrates record-breaking efficiencies in triple-junction solar cells by incorporating thick quantum well superlattices to optimize bandgap properties, achieving 39.5% terrestrial and 34.2% space efficiency.

Contribution

It introduces the use of thick GaInAs/GaAsP quantum well superlattices in triple-junction solar cells to surpass previous efficiency records.

Findings

Achieved 39.5% efficiency under global spectrum.

Achieved 34.2% efficiency under space spectrum.

Demonstrated superior performance over six-junction devices.

Abstract

Multijunction solar cell design is guided by both the theoretical optimal bandgap combination as well as the realistic limitations to materials with these bandgaps. For instance, triple-junction III-V multijunction solar cells commonly use GaAs as a middle cell because of its near-perfect material quality, despite its bandgap being higher than optimal for the global spectrum. Here, we modify the GaAs bandgap using thick GaInAs/GaAsP strain-balanced quantum well (QW) solar cells with excellent voltage and absorption. These high-performance QWs are incorporated into a triple-junction inverted metamorphic multijunction device consisting of a GaInP top cell, GaInAs/GaAsP QW middle cell, and lattice-mismatched GaInAs bottom cell, each of which has been highly optimized. We demonstrate triple-junction efficiencies of 39.5% and 34.2% under the global and space spectra, respectively, which are higher than previous record six-junction devices.