CuI films present promising optoelectronic properties for transparent conductors. However, the high hole concentration in CuI films hinders the controllable modulation of hole mobility, limiting their application in low-dimensional thin-film transistors. In this study, CuI films were prepared through a Cu film iodination method at room temperature, and a systematic investigation was conducted on the modulation of hole concentration and mobility with varying film thickness. The films exhibited a zinc blende structure (γ-phase) with increasing grain size as the thickness increased. The transmittance and optical bandgap of the films decreased with increasing thickness. The correlation of vacancy concentration with changing film thickness was analyzed through photoluminescence spectroscopy, revealing the influence of grain boundary migration on vacancy formation. The reduction in film thickness diminishes the migration of CuI grain boundaries, consequently reducing the probability of Cu vacancy and I vacancy formation, resulting in diminished hole concentration and enhanced hole mobility and film conductivity. The film with a thickness of 20 nm demonstrated optimal performance, with a transmittance of 90%, hole concentration of 4.09 × 1017 cm−3, hole mobility of 506.50 cm2 V−1 s−1, and conductivity of 33.19 S cm−1. This work deepens the understanding of hole transport such as hole concentration and mobility modulation in CuI films, highlighting the importance of controlling grain boundary migration during the film growth process.
Beibei Shi,Jinbiao Jia,Xu Feng,Guangcai Ma,Yangqing Wu,Bingqiang Cao
CuI, as a promising hole transport material, possesses high hole mobility and is compatible with perovskite materials about band structure. Herein, CuI hole transport films are first fabricated by vacuum thermal evaporation procedure for n-i-p perovskite solar cell . The results show that vacuum thermal evaporated CuI films have no obvious influence on perovskite underlayer and 200 nm thick CuI film has the best carrier extraction ability. To further improve the stability of the device, reduced graphene oxides are introduced to avoid the accelerated attenuation caused by the reaction of CuI with Au. Finally, the power conversion efficiency of the dual-modified device improves to 8.69%, with the short circuit current density of 18.86 mA cm −2 , the open circuit voltage of 0.832 V and the filling factor of 0.550. The work demonstrates a potential application of vacuum thermal evaporated CuI films in organic-inorganic hybrid perovskite solar cells.
Self-assembled monolayer (SAM) treatment of gate dielectrics plays a key role in the improvement of the electrical performance of organic thin-film transistors (TFTs) by reducing the interface traps. However, it is rarely explored in inorganic TFTs owing to possible irreversible damage to very thin SAMs during the sputtering and high-temperature annealing processes that are often used to deposit inorganic materials. Here, the feasibility of performance enhancement of inorganic p-type Zn-doped CuI TFTs is explored by a SAM treatment using 3-aminopropyltriethoxysilane (APTES) on the gate dielectric. Our result shows that the TFT performance is significantly enhanced with a 50% reduction in the interface trap density, a 326% increase in the hole mobility from 0.38 to 1.24 cm 2 V -1 s -1 and a 5-fold increase in the current on/off ratio from 2.6 × 10 6 to 1.1 × 10 7 . In addition, the bias stress stability of the TFTs after the treatment is dramatically enhanced by a factor of 10 due to the improved interface properties. The threshold voltage shift is reduced from +19.6 to +1.8 V after 3600 s positive bias stress. The simple yet effective interface treatment approach may have great potential in the fabrication of high-performance inorganic p-type electronic devices.
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