Effect of substrate temperature on structural, optical, and photoelectrochemical properties of Tl2S thin films fabricated using AACVD technique

Abstract

Abstract Thin films of thallium sulphide (Tl2S) were grown on the FTO surface at three different temperatures (500°C, 550°C, and 600°C) using the aerosol-assisted chemical vapor deposition approach. A thallium diethyldithiocarbamate (Tl[CNS2(C2H5)3]) complex was used as a single-source precursor in tetrahydrofuran (THF) solvent under an inert atmosphere of argon in all deposition experiments. The impact of deposition temperature on structural, morphological, and optical properties of Tl2S thin films was explored using different experimental techniques such as X-ray diffraction (XRD), field-emission scanning electron (FESEM) microscopy, and UV-visible spectrophotometry. XRD analysis specifies that crystallite size varies from 120 to 90 nm with the increase in temperature from 500°C to 600°C. FESEM results revealed that Tl2S films were grown as hexagonal, petals, and marigold flower-like particles at 500°C, 550°C, and 600°C, respectively. UV-visible spectrophotometric analysis shows a decrease in band gap energies with temperature: 1.92 eV at 500°C, 1.72 eV at 550°C, and 1.42 eV at 600°C. The photoelectrochemical measurement in terms of linear sweep voltammetry confirms that the temperature variation has a significant effect on the photoconversion efficiency of Tl2S thin films, and photocurrent density increases from 0.56 to 0.76 mA·cm−2 when the temperature is increased from 500°C to 600°C.