Enhancing the Hydrogen Evolution Properties of Kesterite Absorber by Si-Doping in the Surface of CZTS Thin Film

Manoj Vishwakarma, Mukesh Kumar, Mylène Hendrickx, Joke Hadermann, Aadesh P. Singh, Yogita Batra, B. R. Mehta*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)

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 languageEnglish
Article number2002124
Number of pages12
JournalAdvanced Materials Interfaces
Volume8
Issue number10
Early online date1 Apr 2021
DOIs
Publication statusPublished - 21 May 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • CZTS
  • heterostructures
  • photocathodes
  • photocurrent
  • Si-doping
  • water splitting

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