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

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 Si (from x = 0 to 1) yields a band gap rise due shifting conduction minimum towards higher energy states Cu2Zn(Sn1−xSix)S4. CZTSiS thin film prepared by co-sputtering process shows Cu2Zn(Sn1−xSix)S4 (Si-rich) (S-rich) kesterite phases on surface bulk sample, respectively. A significant change electronic properties is observed film. CZTS inverts bending at grain-boundaries from downward upward Fermi level shifts upward. Further, coating CdS ZnO layer improves photocurrent ≈5.57 mA cm−2 −0.41 VRHE CZTSiS/CdS/ZnO which 2.39 times than pure CZTS. flat potential increases ≈0.43 ≈1.31 indicating faster carrier separation electrode–electrolyte interface latter sample. CdS/ZnO layers over significantly reduce charge transfer resistance semiconductor–electrolyte interface.