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Despite the impressive development of metal halide perovskites in diverse optoelectronics, progress on high-performance transistors employing state-of-the-art perovskite channels has been limited due to ion migration and large organic spacer isolation. Herein, we report high-performance hysteresis-free p-channel perovskite thin-film transistors (TFTs) based on methylammonium tin iodide (MASnI3) and rationalise the effects of halide (I/Br/Cl) anion engineering on film quality improvement and tin/iodine vacancy suppression, realising high hole mobilities of 20 cm2 V−1 s−1, current on/off ratios exceeding 107, and threshold voltages of 0 V along with high operational stabilities and reproducibilities. We reveal ion migration has a negligible contribution to the hysteresis of Sn-based perovskite TFTs; instead, minority carrier trapping is the primary cause. Finally, we integrate the perovskite TFTs with commercialised n-channel indium gallium zinc oxide TFTs on a single chip to construct high-gain complementary inverters, facilitating the development of halide perovskite semiconductors for printable electronics and circuits. Progress on high-performance transistor employing perovskite channels has been limited to date. Here, Zhu et al. report hysteresis-free tin-based perovskite thin-film transistors with high hole mobility of 20 cm2V–1S–1, which can be integrated with commercial metal oxide transistors on a single chip. [ABSTRACT FROM AUTHOR]

The development of transparent and high‐performance p‐type semiconductors as a counterpart of n‐type metal oxide semiconductors has attracted significant interest for the integration of complementary circuits and p–n junction devices. This study investigates the effect of trace O2 for high‐performance and solution‐processed inorganic p‐channel Zn‐doped copper iodide (CuI) thin‐film transistors (TFTs) via a combined computation–experiment approach. The absorbed O2 molecules in the CuI film can occupy iodine vacancies, acting as trap passivator. Meanwhile, the strong electronegativity of O2 enables electron capture from the CuI matrix, leading to p‐doping. Trace O2‐treated Zn‐doped CuI TFTs exhibit significantly improved electrical performance compared to untreated devices. Optimized TFTs exhibit a high field‐effect hole mobility of 4.4 cm2 V−1 s−1, high on/off current ratio of ≈107, and small hysteresis. These findings provide a clear basis for realizing reproducible and high‐performance metal‐halide (e.g., CuI and perovskite) optoelectronic devices using low‐cost solution process. [ABSTRACT FROM AUTHOR]

Studies on printable semiconductors and technologies have increased rapidly over recent decades, pioneering novel applications in many fields, such as energy, sensing, logic circuits, and information displays. The newest display technologies are already turning to metal oxide semiconductors, i.e., indium gallium zinc oxide, for the improvements needed to drive active matrix organic light‐emitting diodes. Convenience and portability will be realized with flexible and wearable displays in the future. This report summarizes recent progress on the development of solution‐processed thin film transistors, especially those deposited at low temperatures for next‐generation flexible smart displays. The first part provides an overview on the history and current status of displays. Then, recent advances in state‐of‐the‐art solution‐processed transistors based on different semiconductors are presented, including metal oxides, organic materials, perovskites, and carbon nanotubes. Finally, conclusions are drawn and the remaining challenges and future perspectives are discussed. [ABSTRACT FROM AUTHOR]

Over the past decades, developing high‐performance transparent p‐type semiconductors has become one of the urgent tasks in electronic industry for the integration of complementary circuits and high‐end displays. Unfortunately, there is no satisfied candidate reported to date. In this work, we reported a novel transparent p‐type Zn‐doped CuI semiconductor using low‐temperature and low‐cost solution process for high‐performance transistors and circuits. The optimized transistors exhibited a high hole mobility of 5 cm2 V−1 s−1 and high on/off current ratio of ~107 with excellent operational stability and reproducibility. The integrated CMOS inverter delivered a high peak gain of ~60 with the low power consumption. This study paves the way for realizing transparent, flexible, and large‐area integrated circuits with n‐type metal‐oxide semiconductors. [ABSTRACT FROM AUTHOR]

Transparent polycrystalline p-channel copper bromide (CuBr) thin-film transistors (TFTs) are fabricated using a simple one-step spin coating at room temperature. Optimized CuBr TFTs operate in depletion mode with an on-voltage of 35 V and exhibit a hole mobility of 0.15 cm $^{2}\,\,\text{V}^{-1}\,\,\text{s}^{-1}$ , high ON/OFF current ratio ${\sim }10^{4}$ and cycling bias sweep/air stabilities. The performance is superior to that of most solution-processed p-type oxide TFTs, highlighting CuBr as a promising p-type candidate for next-generation printable transparent electronics. [ABSTRACT FROM AUTHOR]

Developing p‐type transparent semiconductors has attracted great interest over the past decades to realize complementary p‐n junction devices and circuits by cost effective graphic art processes. Here we report two kinds of transparent p‐type Cu‐based transistors (CuI and CuxO), which can be synthesized using solution process at plastic‐compatible temperatures. [ABSTRACT FROM AUTHOR]

We found that during spin-coating and annealing processes, the ambient humidity can have obvious impact on the characteristics of p-channel copper oxide thin-film transistors (TFTs). We studied such impact in great details along with the device operational stability. A dry deposition atmosphere (relative humidity, ${\mathrm {RH}} \le20$ %) is necessary for the best device performance, including a hole mobility of 0.1 cm $^{{2}}\,\,\text{V}^{{-1}}\,\,\text{s}^{{-1}}$ , an on/off current ratio of $> 10^{{4}}$ , and high operational stability (< 2 V threshold voltage shift after 5.5 h of bias stress), attributable to residues with fewer hydroxide defects. These findings offer a clear inspiration for achieving highly stable and reproducible p-channel oxide TFTs through a low-cost solution process. [ABSTRACT FROM AUTHOR]

High‐k alkaline lithium oxide (LiOx) thin films are fabricated by spin‐coating method. The LiOx thin films are annealed at different temperatures and characterized by various techniques. An optimized LiOx dielectric is achieved at an annealing temperature of 300 °C and exhibits wide bandgap of ≈5.5 eV, smooth surface, relatively permittivity of ≈6.7, and low leakage current density. The as‐fabricated LiOx thin films are integrated, as gate dielectrics, in both n‐channel indium oxide (In2O3) and p‐channel cupric oxide (CuO) transistors. The optimized In2O3/LiOx thin‐film transistor (TFT) exhibits high performance and high stability, such as Ion/Ioff of 107, electron mobility of 5.69 cm2 V−1 s−1, subthreshold swing of 70 mV dec−1, negligible hysteresis, and threshold voltage shift of 0.1 V under bias stress for 1.5 h. Meanwhile, the p‐channel CuO TFT based on LiOx dielectric shows high Ion/Ioff of 105 and hole mobility of 1.72 cm2 V−1 s−1. All the electrical performances are achieved at an ultra‐low operating voltage of 2 V. Considering the simple procedure, the moderate annealing temperature, and the low power consumption merits, these outstanding characteristics represent a significant advance toward the development of battery compatible and portable electronics. [ABSTRACT FROM AUTHOR]

Solution-processed metal-oxide thin films based on high dielectric constant (k) materials have been extensively studied for use in low-cost and high-performance thin-film transistors (TFTs). Here, scandium oxide (ScOx) is fabricated as a TFT dielectric with excellent electrical properties using a novel water-inducement method. The thin films are annealed at various temperatures and characterized by using X-ray diffraction, atomic-force microscopy, X-ray photoelectron spectroscopy, optical spectroscopy, and a series of electrical measurements. The optimized ScOxthin film exhibits a low-leakage current density of 0.2 nA cm−2 at 2 MV cm−1, a large areal capacitance of 460 nF cm−2 at 20 Hz and a permittivity of 12.1. To verify the possible applications of ScOx thin films as the gate dielectric in complementary metal oxide semiconductor (CMOS) electronics, they were integrated in both n-type InZnO (IZO) and p-type CuO TFTs for testing. The water-induced full oxide IZO/ScOx TFTs exhibit an excellent performance, including a high electron mobility of 27.7 cm2 V−1 s−1, a large current ratio (IonIoff) of 2.7 × 107 and high stability. Moreover, as far as we know it is the first time that solution-processed p-type oxide TFTs based on a high-k dielectric are achieved. The as-fabricated p-type CuO/ScOx TFTs exhibit a large IonIoff of around 105 and a hole mobility of 0.8 cm2 V−1 at an operating voltage of 3 V. To the best of our knowledge, these electrical parameters are among the highest performances for solution-processed p-type TFTs, which represents a great step towards the achievement of low-cost, all-oxide, and low-power consumption CMOS logics. [ABSTRACT FROM AUTHOR]

Here, a simple, nontoxic, and inexpensive 'water-inducement' technique for the fabrication of oxide thin films at low annealing temperatures is reported. For water-induced (WI) precursor solution, the solvent is composed of water without additional organic additives and catalysts. The thermogravimetric analysis indicates that the annealing temperature can be lowered by prolonging the annealing time. A systematic study is carried out to reveal the annealing condition dependence on the performance of the thin-film transistors (TFTs). The WI indium-zinc oxide (IZO) TFT integrated on SiO2 dielectric, annealed at 300 °C for 2 h, exhibits a saturation mobility of 3.35 cm2 V−1 s−1 and an on-to-off current ratio of ≈108. Interestingly, through prolonging the annealing time to 4 h, the electrical parameters of IZO TFTs annealed at 230 °C are comparable with the TFTs annealed at 300 °C. Finally, fully WI IZO TFT based on YO x dielectric is integrated and investigated. This TFT device can be regarded as 'green electronics' in a true sense, because no organic-related additives are used during the whole device fabrication process. The as-fabricated IZO/YO x TFT exhibits excellent electron transport characteristics with low operating voltage (≈1.5 V), small subthreshold swing voltage of 65 mV dec−1 and the mobility in excess of 25 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

'Ideal' transparent p-type semiconductors are required for the integration of high-performance thin-film transistors (TFTs) and circuits. Although CuI has recently attracted attention owing to its excellent opto-electrical properties, solution processability, and low-temperature synthesis, the uncontrolled copper vacancy generation and subsequent excessive hole doping hinder its use as a semiconductor material in TFT devices. In this study, we propose a doping approach through soft chemical solution process and transparent p-type Zn-doped CuI semiconductor for high-performance TFTs and circuits. The optimised TFTs annealed at 80 °C exhibit a high hole mobility of over 5 cm2 V−1 s−1 and high on/off current ratio of ~107 with good operational stability and reproducibility. The CuI:Zn semiconductors show intrinsic advantages for next-generation TFT applications and wider applications in optoelectronics and energy conversion/storage devices. This study paves the way for the realisation of transparent, flexible, and large-area integrated circuits combined with n-type metal-oxide semiconductor. Designing efficient thin-film transistors and circuits based on transparent p-type semiconductors remains a challenge. Here, the authors propose a solution-based doping approach to realize high performance transparent inorganic p-type semiconductors (Zn-doped CuI) by spin coating at 80 C with good operational stability. [ABSTRACT FROM AUTHOR]

P-Doping Methods: Molecule Charge Transfer Doping for p-Channel Solution-Processed Copper Oxide Transistors (Adv. Funct. Keywords: molecule charge transfer doping; p-type oxide semiconductor; solution process; thin-film transistor EN molecule charge transfer doping p-type oxide semiconductor solution process thin-film transistor 1 1 1 06/13/20 20200615 NES 200615 In article number 2002625, Yong-Young Noh, Ao Liu, and Huihui Zhu demonstrate molecule charge transfer p-doping for p-channel copper oxide (Cu SB I x i sb O) thin-film transistors (TFTs) with a dramatically improved hole mobility of over 20-fold without sacrificing other opto-/electrical parameters. Molecule charge transfer doping, p-type oxide semiconductor, solution process, thin-film transistor. [Extracted from the article]

Keywords: carbon nanotubes; conjugated molecules; flexible display; oxide semiconductors; perovskites; printable semiconductors; thin-film transistors EN carbon nanotubes conjugated molecules flexible display oxide semiconductors perovskites printable semiconductors thin-film transistors 1 1 1 05/18/20 20200515 NES 200515 Semiconductor evolution has greatly promoted the development of high-end displays over the past decades. In article number 1904588, Yong Xu, Yong-Young Noh, and co-workers summarize the recent progress in the development of solution-processed thin-film transistors with various functional inks including metal oxides, organics, carbon nanotubes, and perovskite and their applications in next-generation flexible smart displays. Carbon nanotubes, conjugated molecules, flexible display, oxide semiconductors, perovskites, printable semiconductors, thin-film transistors. [Extracted from the article]

The lack of high-performance p-type semiconducting materials hinders the integration of complementary metal-oxide semiconductors with well-established n-type metal-oxide counterparts. Although tin halide perovskites are promising p-type material candidates, their practical implementation is hindered by excessive hole concentrations and difficulties in precisely controlling crystallization, which leads to poor device performance and yield. In this paper, we propose a formate pseudohalide engineering method to overcome these issues and demonstrate high-performance tin perovskite thin-film transistors (TFTs). The incorporation of formate anion greatly suppresses the vacancy defects at the surfaces of the perovskite films with an increase in crystallinity and grain size. This reduces the hole concentration and eliminates the dependence on the addition of excessive tin fluoride for hole suppression. Hence, high-performance TFTs with a high average field-effect hole mobility of 57.34 cm2 V−1 s−1 and on/off current ratios surpassing 108 can be achieved, approaching p-channel low-temperature polysilicon devices. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we develop a simple and eco-friendly water-inducement method for high- k yttrium oxide (YO x ) dielectric. To prepare YO x thin films at low temperature, yttrium nitrate and deionized water were used as the source materials. No toxic organic materials were required in the YO x coating process. The YO x thin film annealed at 350 °C showed a low leakage current density of 2 × 10 −9 A/cm 2 at 5 MV/cm and a large areal-capacitance of 448 nF/cm 2 at 1 kHz. On the basis of its implementation as the gate dielectric, the fully-water-induced In 2 O 3 TFT based on YO x exhibited a high field-effect mobility of 15.98 cm 2 /Vs, excellent subthreshold swing of 75 mV/dec, an on/off current ratio of 6 × 10 6 , and a negligible hysteresis of 50 mV. The as-fabricated TFT operated at a low voltage (∼1.5 V) and showed high drain current drive capability, enabling oxide TFT with a water-induced high- k dielectric for use in backplane electronics for low-power mobile display applications. [ABSTRACT FROM AUTHOR]