A modified sol-gel synthesis protocol for high-quality ZnSnO₃ thin films with enhanced electrical and optical properties for energy and sensor applications.

This paper presents a modified sol-gel synthesis methodology for producing high-quality ZnSnO₃ thin films with improved optical transparency, electrical conductivity, and gas-sensing capabilities, ideal for renewable energy and sensor applications. Adjusting the annealing temperature from 200 to 500 °C allowed for precise control of phase, transparency, and conductivity. X-ray diffraction showed that temperature drives the transformation from amorphous to crystalline phases. Films annealed at 350 °C exhibited over 85 % transmittance in the visible spectrum and a direct band gap of 3.3 eV, making them excellent candidates for transparent electrodes in future photovoltaic and optoelectronic systems. At 450 °C, electrical testing revealed a low resistivity of 5.2 × 10⁻³ Ω·cm, representing a significant improvement over typical ZnO-based transparent conductive oxide. Gas-sensing studies showed strong responses-75 % for CO₂ at 250 °C and 70 % for NO₂ at 300 °C-with more than 95 % retention after 50 cycles, indicating long-term stability. Energy-efficient transparent electronics, environmental monitoring, and high-sensitivity gas sensors can be reproducibly and scalably fabricated using the updated sol-gel technique.•XRD and UV-Vis corroborated the temperature-driven transformation from amorphous to crystalline ZnSnO₃. Films annealed at 350 °C had a 3.3 eV band gap and over 85 % visible transmittance.•At 450 °C, resistivity decreased to 5.2 × 10⁻³ Ω·cm, resulting in a conductivity of 192 S·cm⁻¹, exceeding standard ZnO TCOs.•Gas sensitivities were 75 % for CO₂ (250 °C) and 70 % for NO₂ (300 °C), with 95 % stability retained after 50 cycles.