Fabrication and characterization of TiO2: ZnO thin films as electron transport material in perovskite solar cell (PSC)

Abstract

In developing quicker, smaller, and more efficient optoelectronic devices, composite thin films are becoming progressively crucial. One reason for using composite thin films is to improve materials optical and electrical properties. Thermal Evaporation is a type of physical vapor deposition that can produce thin films with well-controlled nanostructures that are pure, homogeneous, and conformal. The prime focus of this study was to fabricate TiO2 and composite TiO2:ZnO thin films on ITO-coated glass substrates by thermal Evaporation. The goal of this study was to investigate the optical, structural, and electrical properties of deposited thin films. The optical properties were assessed using UV–Vis and Photoluminescence spectroscopy, and FTIR spectroscopy was used to identify the fingerprint of materials. The crystal structure of deposited thin films was investigated using X-ray diffraction. The changes in morphology induced by adding ZnO content to TiO2 were examined using optical microscopy. SEM investigation corroborated the granular-like structure of thin films, whereas EDX demonstrated the doping and composition of ZnO concentration in TiO2. The electrical measurements were performed using the Van der Pauw technique. Adding ZnO into TiO2 improved transmission, photoconductivity, and optical bandgap to generate a viable electron transport material (ETM) for efficient perovskite solar cells (PSC). XRD results revealed the grain size increase after adding ZnO into TiO2. The transmission was increased to 95%, while the bandgap was decreased from 3.8 eV to 3.68 eV. It was also revealed that after integrating ZnO into TiO2, the generated thin films have stronger visible photoluminescence peaks, and the material's conductivity has been improved. The results indicate that TiO2:ZnO could be employed as an ETM in PSC to improve productivity.