Experimental realization of theory predicted high absorption earth-abundant Cu-V-VI solar absorbers

R.S. Kokenyesi, L. Yu, A. Zunger, D.A. Keszler
Oregon State University, US

Keywords: solar absorbers, Cu-V-VI, thin film, polycrystalline

Summary:

Current solar cell technologies based on crystalline Si wafers and thin film CdTe and CIGS are limited for deployment at the grid parity level (TW production scale). While Si is an abundant element with confirmed record efficiencies, its refinement to solar grade is expensive. The proven thin film technologies, such as CdTe and CIGS, suffer from limited raw materials supply, restraining production levels to only few GW per year. Hence, to solve the growing energy demands with an environmentally conscious renewable and rapidly scalable technology, new solar absorber materials need to be recognized that are made up of earth-abundant elements found in concentrated deposits. In our study, computational approach is used to identify new photovoltaic absorber materials on the basis of the multidimensional metric “Spectroscopic Limited Maximum Efficiency”. Application of this metric to the Cu-V-VI system allowed us to understand the physics of absorption in these materials and to identify several candidates that should exhibit higher absorption than CuInSe2 in very thin-film form. In this contribution, we confirm the main theoretical predictions, demonstrating that polycrystalline thin films of select compositions, CuSbS2 (EG=1.44 eV) and Cu3SbS4 (EG=0.88 eV), exhibit exceptionally high absorption.