Enhanced Vis-NIR light absorption and thickness effect of Mo-modified SnO2 thin films: A first principle calculation study

[Display omitted] •Thickness effect on pristine, defective, Mo-doped and Mon-adsorbed SnO2 system.•The Vis-NIR light absorption of SnO2 is significantly enhanced by Mo modification.•The Vis-NIR light absorption is promoted by increasing the Mo cluster size.•Mon cluster adsorption makes significant enhancement in Vis-NIR light absorption. The thickness effect on ultraviolet, visible and near-infrared (UV–Vis-NIR) light absorption of Mo-modified tin oxide (SnO2) thin films is investigated by the first principle calculation based on the density functional theory. The electronic structures and optical properties of the pristine, defective, Mo-doped and Mon (n = 1, 2, 3, 4) cluster adsorbed SnO2 (110) surfaces with film thickness from 0.594 to 3.273 nm are discussed. The results show that the pristine SnO2 semiconductor thin films can hardly absorb the Vis-NIR light. The absorption peaks in the Vis-NIR light region of the defective SnO2 (110) surface increase with the film thickness. The Vis-NIR light absorption of SnO2 is significantly enhanced by Mo modification. Mon cluster adsorption on SnO2 makes the greatest enhancement in Vis-NIR light absorption. The surface modification of Mo is concluded to be a promising route for SnO2 semiconductor thin film as a photocatalyst under Vis-NIR light irradiation.