Abstract Copper iodide (CuI) thin films were prepared on a glass substrate by a facile high pressure (HP)‐PECVD method at room temperature. For this, CuI powder was dissolved in CH3CN. The CuI vapor with plasma was investigated by Optical Emission Spectroscopic (OES) data for identifying the species in the plasma. The XRD study reveals the polycrystalline nature of the films. The SEM analyses indicate the homogeneity of the films. The EDS mapping confirms that the thin films mostly consisted of carbon followed by nitrogen, copper and iodine, respectively. The band gaps of CuI thin films were in the range of ~2.71–3.14 eV. The high transmittance and band gap engineering in HP‐PECVD‐synthesized CuI thin films indicates their potential use as window and hole transport layers in low cost solar cells.
