Issue 48, 2023

Band gap engineering by cationic substitution in Sn(Zr1−xTix)Se3 alloy for bottom sub-cell application in solar cells

Abstract

Next-generation solar cells employ multiple junctions to push power conversion efficiency beyond the Shockley–Queisser limit. As the tandem devices based on c-Si and wide band gap absorbers are showing impressive performances, the introduction of a third junction can boost the efficiency even higher. For a three-junction solar cell with c-Si as the middle one, the optimum band gaps for the top and bottom sub-cells are 1.7 and 0.7 eV, respectively. While there are numerous wide band gap compounds being explored and studied for the top sub-cells, there is a lack of suitable materials for bottom sub-cells. In this work, we explore a novel Sn(Zr1−xTix)Se3 alloy system and evaluate its fundamental optoelectronic properties. Using a solid state reaction, we synthesized Sn(Zr1−xTix)Se3 materials with various Ti/Zr ratios in both powder and single crystal forms. Structural, optical, and electrical properties were measured as a function of the Ti/Zr ratio. We found that Sn(Zr1−xTix)Se3 crystallizes in the needle-like phase and is stable up to x = 0.44. With an increase in the Ti/Zr ratio, the absorption edge of Sn(Zr1−xTix)Se3 shifted towards lower energy and the lowest band gap achieved at x = 0.42 was 0.78 ± 0.01 eV. Electrical measurements revealed that the resistivity of Sn(Zr1−xTix)Se3 with respect to the Ti/Zr ratio was non-linear and had three distinct regions. Finally, we determined that Sn(Zr1−xTix)Se3 with Ti-rich composition is a direct semiconductor, has a very high absorption coefficient and the band gap is located near the optimal region for the bottom sub-cell absorber, making it a promising material candidate for multijunction solar cell applications.

Graphical abstract: Band gap engineering by cationic substitution in Sn(Zr1−xTix)Se3 alloy for bottom sub-cell application in solar cells

Supplementary files

Article information

Article type
Paper
Submitted
12 Sep 2023
Accepted
16 Nov 2023
First published
27 Nov 2023
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2023,11, 26488-26498

Band gap engineering by cationic substitution in Sn(Zr1−xTix)Se3 alloy for bottom sub-cell application in solar cells

R. Kondrotas, V. Pakštas, M. Franckevičius, A. Suchodolskis, S. Tumėnas, V. Jašinskas, R. Juškėnas, A. Krotkus, K. Muska and M. Kauk-Kuusik, J. Mater. Chem. A, 2023, 11, 26488 DOI: 10.1039/D3TA05550G

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