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Investigating Sub-bandgap Spectral Effects in GaInP-on-Ge Solar Cells



Brianna Conrad, Behrang Hamadani


There is a fundamental understanding in photovoltaics that sub-bandgap light will not be absorbed in the solar cell and therefore will not affect the power generation. We have shown a novel phenomenon in which sub-bandgap illumination is required for good electrical performance in III-V solar cells on heterosubstrates. We investigate this effect in GaInP cells on Ge substrates with current-voltage measurements under varying spectra and irradiances. This has implications for device characterization, the development of solar cells both on heterosubstrates and for conditions lacking long-wavelength light, and the prediction of device performance under spectra that differ from the test conditions.
Proceedings Title
48th IEEE Photovoltaics Specialists Conference (PVSC)
Conference Dates
June 20-25, 2021
Conference Location
Virtual, MD, US


III-V and Concentrator PV, Characterization of PV, Circuit analysis, Photovoltaic cells


Conrad, B. and Hamadani, B. (2021), Investigating Sub-bandgap Spectral Effects in GaInP-on-Ge Solar Cells, 48th IEEE Photovoltaics Specialists Conference (PVSC), Virtual, MD, US, [online],, (Accessed April 17, 2024)
Created August 26, 2021, Updated February 28, 2024