Abstract
In this work, the effects of Si-doping in Cu2ZnSnS4 are examined computationally and experimentally. The density functional theory calculations show that an increasing concentration of Si (from x = 0 to x = 1) yields a band gap rise due to shifting of the conduction band minimum towards higher energy states in the Cu2Zn(Sn1−xSix)S4. CZTSiS thin film prepared by co-sputtering process shows Cu2Zn(Sn1−xSix)S4 (Si-rich) and Cu2ZnSnS4 (S-rich) kesterite phases on the surface and in the bulk of the sample, respectively. A significant change in surface electronic properties is observed in CZTSiS thin film. Si-doping in CZTS inverts the band bending at grain-boundaries from downward to upward and the Fermi level of CZTSiS shifts upward. Further, the coating of the CdS and ZnO layer improves the photocurrent to ≈5.57 mA cm−2 at −0.41 VRHE in the CZTSiS/CdS/ZnO sample, which is 2.39 times higher than that of pure CZTS. The flat band potential increases from CZTS ≈0.43 VRHE to CZTSiS/CdS/ZnO ≈1.31 VRHE indicating the faster carrier separation process at the electrode–electrolyte interface in the latter sample. CdS/ZnO layers over CZTSiS significantly reduce the charge transfer resistance at the semiconductor–electrolyte interface.
Original language | English |
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Article number | 2002124 |
Number of pages | 12 |
Journal | Advanced Materials Interfaces |
Volume | 8 |
Issue number | 10 |
Early online date | 1 Apr 2021 |
DOIs | |
Publication status | Published - 21 May 2021 |
MoE publication type | A1 Journal article-refereed |
Keywords
- CZTS
- heterostructures
- photocathodes
- photocurrent
- Si-doping
- water splitting