Major obstacles towards power efficient complementary electronics employing oxide thin-film transistors (TFTs) lie in the lack of equivalent well performing p-channel devices. Here, we report a significant performance enhancement of solution-processed p-type nickel oxide (NiOx) TFTs by introducing Sn dopant. The Sn-doped NiOx (Sn-NiOx) TFTs annealed at 280 °C demonstrate substantially improved electrical performances with the increase in the on/off current ratio (Ion/Ioff) by ∼100 times, field-effect mobility (μlin) by ∼3 times, and the decrease in subthreshold swing by half, comparing with those of pristine NiOx TFTs. X-ray photoelectron spectroscopy and X-ray diffraction results confirm that Sn atoms tend to substitute Ni sites and induce more amorphous phase. A decrease in density of states in the gap of NiOx by Sn doping and the shift of Fermi level (EF) into the midgap lead to the improvements of TFT performances. As a result, Sn-NiOx can be a promising material for the next-generation, oxide-based electronics.

The effects of UV-ozone (UVO) irradiation on copper-doped nickel acetate and its applicability to perovskite solar cells were investigated. UVO irradiation of copper-doped nickel acetate significantly increased the electrical conductivity (from 4.28 × 10(-4) S cm(-1) to 5.66 × 10(-2) S cm(-1)), which is due to the increased carrier concentration (from 3.53 × 10(13) cm(-3) to 2.41 × 10(16) cm(-3)), and the charge extraction efficiency was enhanced, leading to better compatibility with the hole transport layer. By UVO irradiation, the work function was increased from 4.95 eV to 5.33 eV by the surface dipole formation, which effectively reduced the interface barrier between the hole transport layer and the MAPbI3 light absorbing layer. UVO Irradiation of the underlying layer also allows the MAPbI3 precursors to form better morphology with highly arranged crystallinity. Compared to the cells using non-irradiated copper doped nickel acetate, UVO-irradiated copper-doped nickel acetate devices showed an enhanced open-circuit voltage (3% increase), short circuit current (16% increase), fill factor (5% increase), showing an enhanced power conversion efficiency of 12.2% (21% increase).

We studied solution-processed amorphous indium–zinc–tin oxide (a-IZTO) thin-film transistors (TFTs) with spin-coated zirconium oxide (ZrO x ) as the gate insulator. The ZrO x gate insulator was used without and with UV/O3 treatment. The TFTs with an untreated ZrO x gate dielectric showed a saturation mobility (μsat) of 0.91 ± 0.29 cm2 V−1 s−1, a threshold voltage (V th) of 0.28 ± 0.36 V, a subthreshold swing (SS) of 199 ± 37.17 mV/dec, and a current ratio (I ON/I OFF) of ∼107. The TFTs with a UV/O3-treated ZrO x gate insulator exhibited μsat of 2.65 ± 0.43 cm2 V−1 s−1, V th of 0.44 ± 0.35 V, SS of 133 ± 24.81 mV/dec, and I ON/I OFF of ∼108. Hysteresis was 0.32 V in the untreated TFTs and was eliminated by UV/O3 treatment. Also, the leakage current decreased significantly when the IZTO TFT was coated onto a UV/O3-treated ZrO x gate insulator.

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Nickel oxide (NiO) thin film was synthesized on glass substrate by low-cost sol-gel solution process at 300 °C under ambient condition. The optical properties confirmed the high transparency over visible region and estimated optical band gap of 3.53 eV. Bottom-gate top-contact thin film transistors (TFTs) employing NiO film as active layer were fabricated via conventional photolithography. The electrical property of the NiO TFTs exhibited p-channel operation and field effect mobility of 0.077 cm 2 /V•s. This work reported the potential of NiO TFTs with p-channel characteristics using easily accessed solution process.