Spray-pyrolyzed rare-earth dysprosium-doped SnO2 thin films for plausible photocatalytic application

Abstract

Rare-earth element dysprosium (Dy)-doped SnO<inf>2</inf> plays a crucial role in optoelectronics due to its tunable emission property in the visible region. Using simple spray pyrolysis process, trivalent rare-earth Dy (0–5 wt%) is successfully incorporated into the SnO<inf>2</inf> lattice as Dy-doped SnO<inf>2</inf> (DTO) thin films. X-ray diffraction measurements indicate that the films are considerably textured. Binding energy and elemental charge state are explored using X-ray photoelectron spectroscopy. Optical transmittance of 88.17% and band gap of 3.99 eV is observed for 2 wt% Dy-doped (DTO2) film. Among all the doped films, DTO2 film shows higher hydrophilicity (contact angle 70.7°) due to higher surface roughness (5.71 nm), which is beneficial for photocatalytic activity. The DTO2 film also shows highest carrier concentration (1.8 × 1019 cm−3) and electrical conductivity (3.19 Scm−1). Although, the electrical sheet resistance of the DTO films is high, it can be fine-tuned by further careful optimization of several deposition and/or doping parameters. It is observed that 2 wt% Dy doping into the SnO<inf>2</inf> lattice aids the tunability of its optical and electrical properties according to device requirements. Photocatalytic activity of all the spray-pyrolyzed thin films is investigated by degrading methylene blue (MB) dye. The degradation efficiency is found to be highest for DTO2 film (~ 86% for 240 min) under visible LED light irradiation supported by a defect mediated mechanism. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.