Work

Narrow-bandwidth solar upconversion: Case studies of existing systems and generalized fundamental limits

Year: 2013

Type: article

Abstract: Upconversion of sub-bandgap photons is a promising approach to exceed the Shockley-Queisser limit in solar technologies. Calculations have indicated that ideal, upconverter-enhanced cell efficiencies can exceed 44% for non-concentrated sunlight, but such improvements have yet to be observed experimentally. To explain this discrepancy, we develop a thermodynamic model of an upconverter-cell considering a highly realistic narrow-band, non-unity-quantum-yield upconverter. As expected, solar cell efficiencies increase with increasing upconverter bandwidth and quantum yield, with maximum efficiency enhancements found for near-infrared upconverter absorption bands. Our model indicates that existing bimolecular and lanthanide-based upconverters will not improve cell efficiencies more than 1%, consistent with recent experiments. However, our calculations show that these upconverters can significantly increase cell efficiencies from 28% to over 34% with improved quantum yield, despite their narrow bandwidths. Our results highlight the interplay of absorption and quantum yield in upconversion, and provide a platform for optimizing future solar upconverter designs.

Source: Journal of Applied Physics

DOI: 10.1063/1.4796092

Authors: Justin A. Briggs, Ashwin C. Atre, Jennifer A. Dionne

Institution: Stanford University

Language: English

Topic: Luminescence Properties of Advanced Materials

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

SDG: Affordable and clean energy

Open Access status: green

Funder: U.S. Department of Energy