Tuning Hydrophilicity and Photoresponse by Interfacial Ag Diffusion in the Sb2S3 Layer for Optoelectronic Applications: An Experimental and Computational Study

Antimony sulfide (Sb2S3) from group III2–VI3 is a very capable semiconducting candidate for tandem solar cells owing to its suitable optoelectronic properties. The doping of Ag tailors the optoelectronic and surface properties for different applications. In the current study, Ag/Sb2S3 bilayer films were annealed at different temperatures. The cross-sectional view by FESEM inferred the bilayer and the interdiffusion of Ag into the Sb2S3 layer. The porosity in the film’s surface decreased upon annealing, as seen from the surface morphology. The confirmation of the elements was inferred from the EDS data, while the amorphous structure was verified from X-ray diffraction analysis. The effect of annealing on the different optical parameters was determined from the UV–vis-NIR spectra and related calculations. The optical bandgap, extinction coefficient, refractive index, and dielectric parameters changed with the intermixing of Ag into the Sb2S3 layer upon annealing. The χ(3) value changed from 4.560 × 10–18 to 2.086 × 10–18 m2/V2, and the nonlinear refractive index varied from 4.324 × 10–17 to 2.165 × 10–17 m2/V2 upon annealing. The hydrophilicity increased with annealing, as found from the contact angle measurement. The change in photoconductivity upon annealing is very useful for visible light photodetection. The computational study supported the changes in the films upon annealing.