Effective role of thickness on structural, electrical and optical properties of lead sulphide thin films for photovoltaic applications

The n-type lead sulphide thin films were deposited at 350 °C substrate temperature on glass substrates using advanced spray pyrolysis technique. The thickness of the thin films played an important role to improve the properties of lead sulphide and to use in device fabrication apart from various deposition parameters. The films deposited at thickness of 520 nm resulted in a well oriented polycrystalline with face-centered cubic structure. An enhancement in the crystallite size with increase in film thickness was evidenced by XRD and SEM. The variation in crystallite size of films associated with different thickness provides a significant control over optical and electrical properties. The resistivity of the thin films decreased with an increase in thickness was of the order of 102 Ω cm. The activation energy and optical band gap of the films deposited at optimized condition were found to be 0.20 eV and 1.22 eV, respectively. The absorption coefficient of the films was found to be 106 cm−1. Results prove that the lead sulphide films synthesized using spray technique appeal its adaptability for potential photovoltaic applications in solar cells.