Highly Conductive p-Type Transparent Conducting Electrode with Sulfur-Doped Copper Iodide
Kyunghan Ahn, Ga Hye Kim, Sejun Kim, Jihyun Kim, Gi‐Seong Ryu, Paul Lee, Byungki Ryu, Jung Young Cho, Yong‐Hoon Kim, Joohoon Kang, Hyungjun Kim, Yong‐Young Noh, Myung‐Gil Kim
Abstract
Although n-type transparent conductors have been commercialized with high optical transmittance and electrical conductivity, the realization of their p-type counterparts has been a challenging problem. Here, we report the synthesis of a highly conductive transparent p-type sulfur-doped CuI (CuI:S) thin film using a liquid-iodination method with a thiol additive. The CuI:S film shows a remarkably high electrical conductivity of 511 S cm–1 with an optical transmittance of greater than 80%. Furthermore, additional hole doping of CuI:S with H2O2 treatment improves the electrical conductivity to 596 S cm–1. Consequently, CuI:S exhibits a record-high figure of merit (FOM) value of 63,000 M Ω–1 (73,000 M Ω–1 with H2O2 treatment), which is ∼370% (∼430% with H2O2 treatment) higher than the previously reported record-high FOM value. The highly conducting CuI:S electrode is successfully applied as transparent conducting electrodes of the organic light-emitting diode and transparent p-type thin-film transistor. The liquid-iodination chemical method with unconventional control of the reaction parameters can be generalized to produce high-quality metal halide thin films, allowing them to be applicable for transparent electronics and optoelectronics.