Highly transparent and conductive p-type CuI films by optimized solid-iodination at room temperature

p-type CuI films with optimized optoelectronic performance were synthesized by solid-phase iodination of Cu₃N precursor films at room temperature. The effects of the deposition power of Cu₃N precursors on the structural, electrical, and optical properties of the CuI films were systematically investigated. X-ray diffraction results show that all the CuI films possess a zinc-blende structure. When the deposition power of Cu₃N precursors was 140 W, the CuI films present a high transmittance above 84% in the visible region, due to their smaller root-mean-square roughness values of 9.23 nm. Moreover, these films also have a low resistivity of 1.63 × 10^-2Ω·cm and a boosted figure of merit of 140.7 MΩ^-1. These results are significant achievements among various p-types TCOs, confirming the promising prospects of CuI as a p-type transparent semiconductor applied in transparent electronics.