Growth and characterization of nanostructured CdS/Polyaniline/CuInSe2 thin films for solar cell applications

In the present paper, we report about synthesis of nanostructured organic–inorganic heterojunction of CdS/Polyaniline/CuInSe2 thin films by cost effective chemical route at room temperature, for solar cell application. As such obtained thin films are characterized for structural, compositional, morphological, optical and electrical properties by X-ray diffraction (XRD) pattern, energy dispersive X-ray (EDAX) analysis, scanning electron microscopy (SEM), optical absorbance spectra and I–V response respectively. The XRD reveals the polycrystalline nature of the thin films having tetragonal crystal structure and a crystallite size of 19 nm. The presence of observed and expected elements in the EDAX spectra confirms the elemental compositions in CdS/Polyaniline/CuInSe2 thin films. From SEM images it can be inferred that the surface morphology of the Polyaniline thin films exists like clothing fibers, while CdS/CuInSe2 shows granular shape particles distributed over the substrate and the SEM of CdS/Polyaniline/CuInSe2 represents mixing and attachment of circular particles to fiber like structure. The optical absorbance spectra have shown red shift in absorbance strength and energy band gap value of CdS/CuInSe2 from ~ 1.36 eV to ~ 1.62 eV upon formation of CdS/Polyaniline/CuInSe2 thin film. The I–V response of CdS/CuInSe2 and CdS/Polyaniline/CuInSe2 measured under dark and illumination to 100 mW/cm2 light, exhibited the solar characteristics from these graphs and the conversion efficiency calculated is observed to be 0.26 and 0.55% for CdS/CuInSe2 and CdS/Polyaniline/CuInSe2 thin films respectively.