Unraveling the electrical properties of solution-processed copper iodide thin films for CuI/n-Si solar cells

[Display omitted] •The CuI thin films have been deposited by spin coating with direct liquid-phase iodination of the films.•The XRD study reveals that CuI thin films are polycrystalline whose crystal quality improves due to I-doping.•The SEM study indicates that surface of the CuI films become uniform due to liquid-phase iodination in film.•The electrical conductivity, optical transmittance and band gap increase due to iodination.•These results suggest suitability of synthesized CuI thin films for the use in CuI/n-Si solar cells. The effects of temperature and liquid-phase iodination on the electrical property of spin coated CuI thin films have been investigated in details. The XRD study indicates that CuI thin films are polycrystalline in nature and I-doping enhances the crystal quality and size of the films. The SEM images show that the surface uniformity of the CuI thin films increases due to I-doping. The doping of iodine increases the conductivity as well as carrier concentration and mobility of the films as confirmed by Hall study. The temperature dependent resistivity of CuI film shows a sharp fall of resistivity at ˜80 °C for un-doped films whereas this behavior disappears for I-doped films. The optical transmittance and band gap of the I-doped films also increases indicating high degeneracy of the films. These findings imply that I-doped spin coated CuI thin films are potential candidates for the solution-processed CuI/n-Si solar cells.