Study of structural and electrical properties of CuInSe2 thin films prepared by spray pyrolysis technique

In this study, copper indium selenide (CuInSe2) thin films were successfully prepared on glass substrate using the spray pyrolysis technique, and the structural and electrical properties of films were systematically investigated. The motivation for this research stems from the growing demand for efficient, low-cost absorber materials in thin-film photovoltaic and optoelectronic applications. The structural analysis using X-ray diffraction revealed that the prepared films possess a chalcopyrite crystalline phase (JCPDS card No. 40-1487) with a crystallite size of approximately 55.79 nm, indicating good crystallinity. Field Emission Scanning Electron Microscopy (FESEM) analysis showed that the surface morphology of the films is smooth and uniform, which is desirable for device fabrication. Energy-dispersive X-ray spectroscopy (EDS) confirmed the elemental composition, indicating the presence of copper (Cu), indium (In), and selenium (Se) without any secondary phases. Electrical characterization revealed that the films exhibit a resistivity of 4.93625 Ω·m for a film thickness of 44 nm. The temperature coefficient of resistance (TCR) was found to be negative (-0.00538 /°C), confirming the semiconducting nature of the films. Activation energy values were calculated as 0.2779 eV in the high-temperature region (HTR) and 0.0138 eV in the low-temperature region (LTR), suggesting thermally activated conduction mechanisms. These results demonstrate that spray-deposited CuInSe2 thin films possess promising structural and electrical characteristics, making them suitable candidates for future optoelectronic and photovoltaic applications.