Metamorphic III–V Solar Cells: Recent Progress and Potential

Journal Article · Fri Jan 01 04:00:00 EST 2016 · IEEE Journal of Photovoltaics

DOI:https://doi.org/10.1109/JPHOTOV.2015.2501722· OSTI ID:1330003

Garcia, Ivan; France, Ryan M.; Geisz, John F.; McMahon, William E.; Steiner, Myles A.; Johnston, Steve; Friedman, Daniel J.

Inverted metamorphic multijunction solar cells have been demonstrated to be a pathway to achieve the highest photovoltaic (PV) conversion efficiencies. Attaining high-quality lattice-mismatched (metamorphic) semiconductor devices is challenging. However, recent improvements to compositionally graded buffer epitaxy and junction structures have led to the achievement of high-quality metamorphic solar cells exhibiting internal luminescence efficiencies over 90%. For this high material quality, photon recycling is significant, and therefore, the optical environment of the solar cell becomes important. In this paper, we first present recent progress and performance results for 1- and 0.7-eV GaInAs solar cells grown on GaAs substrates. Then, an electrooptical model is used to assess the potential performance improvements in current metamorphic solar cells under different realizable design scenarios. The results show that the quality of 1-eV subcells is such that further improving its electronic quality does not produce significant Voc increases in the four-junction inverted metamorphic subcells, unless a back reflector is used to enhance photon recycling, which would significantly complicate the structure. Conversely, improving the electronic quality of the 0.7-eV subcell would lead to significant Voc boosts, driving the progress of four-junction inverted metamorphic solar cells.

• Research Organization: NREL (National Renewable Energy Laboratory (NREL), Golden, CO (United States))
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1330003
• Report Number(s): NREL/JA-5J00-67329
• Journal Information: IEEE Journal of Photovoltaics, Journal Name: IEEE Journal of Photovoltaics Journal Issue: 1 Vol. 6; ISSN 2156-3381
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
gallium arsenide
lattices
photovoltaic cells
rough surfaces
strain
substrates
surface roughness