Ge-alloyed kesterite thin-film solar cells: previous investigations and current status – a comprehensive review
(2023) Journal of Materials Chemistry A — Vol. 11, n° 25, p. 13174-13194 (2023)
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- Authors
Scaffidi, Romain 
Birant, Gizem Brammertz, Guy Vermang, Bart
- Abstract
- The incorporation of Ge into kesterite thin-film absorbers for photovoltaic (PV) applications is thoroughly reviewed. Kesterite materials constitute a promising and critical raw material-free alternative to other inorganic thin-film PV compounds such as Cu(In,Ga)Se2 and CdTe. The interest in Ge alloying is to solve the critical open-circuit voltage (Voc) deficit for kesterite solar cells, which is still unresolved and under strong debate. First, the substitution of Sn with Ge from 0 to 100% in the composition of Cu2Zn(Sn1−x,Gex)(Sy,Se1−y)4 absorbers is largely discussed, with a complete overview on the existing literature. It is concluded that fine composition tuning is essential to ensure the Ge-induced enhancement of morphology and single-phase growth through a modified reaction pathway. In this regard, choosing between vacuum- and non vacuum-based deposition methods also plays a crucial role, since the former allows further up-scaling whereas the latter leads to higher thin-film quality. Second, at the solar cell level, Se-rich devices with less than 40% Ge currently exhibit the lowest Voc and fill factor deficits with the highest efficiencies beyond 13%. This is mainly due to defect and band tail compensation as well as a graded bandgap and enlarged crystalline grains. This study unveils encouraging prospects for Ge-boosted kesterite PV devices.
- Affiliations
Hasselt University IMO-IMOMEC imec IMO-IMOMEC
Citations
Scaffidi, R., Birant, G., Brammertz, G., de Wild, J., Flandre, D., & Vermang, B. (2023). Ge-alloyed kesterite thin-film solar cells: previous investigations and current status – a comprehensive review. Journal of Materials Chemistry A, 11(25), 13174-13194. https://doi.org/10.1039/d3ta01218b (Original work published 2023)