Surface-enhanced p-type transparent conducting CuI−Ga2O3 films with high hole transport performance and stability

• Published in: Journal of alloys and compounds Vol. 988; p. 174309
• Main Authors: Xue, Ruibin, Gao, Gang, Yang, Lei, Xu, Liangge, Zhang, Yumin, Zhu, Jiaqi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-06-2024
• Subjects: Copper iodide film; High hole mobility; P-type transparent conductor; Stability; High hole mobility; Stability; Copper iodide film; P-type transparent conductor
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2024.174309

CuI is a wide bandgap p-type transparent conductor with promising optoelectronic properties. However, conventional CuI films prepared through the iodination of Cu films exhibit rough surface, poor stability and excessively high hole concentration, hindering its application. Herein, we introduce CuI−Ga2O3 composite films as a substitution to overcome the shortcomings of pure CuI. During the iodination process, Ga2O3 hindered the mobility of CuI grain boundaries, resulting in small grain size and low surface roughness. After the charge re-equilibrium and low-energy carrier filtering at the interface between Ga2O3 and CuI, the hole concentration in the films decreased by an order of magnitude. Due to the interface effect of Ga2O3 at the grain boundaries of CuI, the hole mobility increased by 5 times, and the conductivity improved by 53%. The ultra-wide band gap of Ga2O3 enhanced the transmittance of CuI films in short wavelength region. Ga2O3 served to passivate the grain boundaries of CuI, preventing the oxidation of CuI and the loss of iodine, consequently improving the stability of the films. This work will deepen the understanding of the failure and hole transport mechanisms of CuI films.
•The second phase Ga2O3 inhibits the movement of CuI grain boundaries.•Ga2O3 reduces the surface roughness of CuI films.•CuI−Ga2O3 films have lower hole concentration, higher conductivity and hole mobility.•CuI−Ga2O3 films exhibit better stability in ambient than pure CuI films.