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 CuN precursor films at room temperature. The effects of the deposition power of CuN 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 CuN 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 × 10Ω·cm and a boosted figure of merit of 140.7 MΩ. 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.