Ultrahigh-Mobility and Solution-Processed Inorganic P-Channel Thin-Film Transistors Based on a Transition-Metal Halide Semiconductor

Abstract

The development of p-channel devices with comparable electrical performances to their n-channel counterparts has been delayed due to the lack of p-type semiconductor materials and device optimization. In this present work, we successfully demonstrated p-channel inorganic thin-film transistors (TFTs) with high hole mobilities similar to the values of n-channel devices. To boost the device performance, the solution-processed copper iodide (CuI) semiconductor was gated by a solid polymer electrolyte. The electrolyte gating could realize electrical double layer (EDL) formation and a three-dimensional carrier transport channel and thus substantially increased charge accumulation in the channel region and realized a high mobility above 90 cm2/(V s) (45.12 ± 22.19 cm2/(V s) on average). In addition, due to the high-capacitance EDL formed by electrolyte gating, the CuI TFTs exhibited a low operation voltage below 0.5 V (V th = −0.045 V) and a high ON current level of 0.7 mA with an ON/OFF ratio of 1.52 × 103. We also evaluated the operational stabilities of CuI TFTs and the devices showed 80% retention under electrical/mechanical stress. All the active layers of the transistors were fabricated by solution processes at low temperatures (<100 °C), indicating their potential use for flexible, wearable, and high-performance electronic applications.

Engineering Copper Iodide (CuI) for Multifunctional p‐Type Transparent Semiconductors and Conductors

“…[ 9 , 44 , 94 , 95 , 96 ] Benefiting from its simplicity and low cost, spin‐coating has become the most commonly used solution‐processing method in laboratories (Figure 3f ). To prepare the precursor inks, the CuI powder can be easily dissolved in different solvents, such as acetonitrile, [ 40 , 44 , 97 , 98 , 99 ] 2‐methoxyethanol, [ 42 , 100 ] dipropyl sulfide, [ 101 , 102 ] and even deionized water. [ 103 ] Solvent selection has a significant effect on the CuI film deposition temperature and quality.…”

High Performance of Solution-Processed Amorphous p-Channel Copper-Tin-Sulfur-Gallium Oxide Thin-Film Transistors by UV/O3 Photocuring

“…The binding energy peaks for Ga 2p of the 0, 2, and 5 min UV/O 3 -treated CTSGO films are shown in Figure S11d (Supporting Information). The small shift of the binding energy peak toward lower energy indicates increased metal-oxygen bond formation. ,− This change is favorable for forming a conductive channel at/near the semiconductor/GI interface. The film UV/O 3 -treated for a prolonged time (5 min) increases oxygen-related vacancies (V o + OH = 38.95%) and decreases the M–O–M network, which can be seen in Figure c.…”

“…In p-type MO semiconductors, the carrier conduction path is formed by anisotropic, localized O 2p orbitals in the valence band, which leads to a large hole effective mass and low hole mobility (μ h ). − Note that the oxygen-related vacancies in the MO lead to low carrier mobility and degrade device performance. A SnO TFT shows higher field-effect mobility (μ FE ) compared to CuO, NiO, and Cu 2 O TFTs, − exhibiting a relatively high μ FE of >1 cm 2 V –1 s –1 due to the delocalized Sn 5s states at the valence band (VB). Even with high μ FE , it shows an unstable phase.…”

Copper halide anion engineering for p-channel electrolyte-gated transistors with superior operational reliability

“…18,21 Recently, metal halide materials including copper iodide (CuI) have been actively investigated as high-mobility p-type inorganic semiconductors to solve these problems, primarily owing to their orbital hybridization and low hole effective mass. [22][23][24][25][26][27][28][29] Accordingly, TFTs based on metal halide semiconductors with a high-k organic/inorganic dielectric and polymer electrolyte dielectric accomplish low operation voltages and extremely high hole mobilities, even over 10 cm 2 V À1 s À1 . [22][23][24][25][26][27][28][29] CuI semiconductors offer other advantages, such as optical transparency and solution processability at a low temperature of B100 1C.…”