High-performance p-type transparent conducting CuI-Cu2O thin films with enhanced hole mobility, surface, and stability

Low-temperature processable p-type transparent conductors are essential for flexible transparent electronics. Current research focuses primarily on wide-band gap copper-based oxides for p-type transparent conductors. However, these oxides generally exhibit inferior performance compared to their n-type counterparts, and their high preparation temperature is unfavorable for flexible electronic applications. CuI serves as a p-type transparent conductor with the ability to be prepared at low temperatures while possessing properties comparable to n-type transparent conductors. The conventional method for CuI film fabrication involves iodination of Cu films. Nevertheless, films produced through this approach exhibit a frosted-glass-like appearance and challenging-to-regulate electrical properties, rendering them unsuitable for electronic devices. In this study, we successfully developed composite films of CuI-Cu2O, demonstrating improved surface morphology and electronic properties at room temperature. The inclusion of Cu2O suppresses the migration of CuI grain boundaries during the iodination process, leading to a reduction in CuI grain size and the formation of a polycrystalline structure with a smoother surface. The increased concentration of grain boundaries within the films, along with charge redistribution between Cu2O and CuI, results in a decrease in hole concentration. As the Cu2O content increases, the relative concentration of I vacancies in the films decreases, leading to an enhancement in hole mobility. The film conductivity initially rises and subsequently decreases with higher Cu2O content. For CuI-Cu2O films with optimized Cu2O composition, visible region transparency ranges from 70% to 80%, hole concentration measures 6.16 x 10(18 )cm(-3), hole mobility reaches 25.40 cm(2) V-1 s(-1), and conductivity amounts to 18.57 S cm(-1). Furthermore, after a period of six months, the electrical properties of CuI-Cu2O films exhibit greater stability compared to pure CuI films. These findings are expected to expedite the widespread application of CuI films within transparent electronics.

Automated summary

In this study, composite films of CuI-Cu2O were successfully developed, with improved surface morphology and electronic properties. The optimized CuI-Cu2O films demonstrated good transparency, low hole concentration, high hole mobility, and high conductivity. Additionally, the electrical properties of CuI-Cu2O films exhibited greater stability compared to pure CuI films.