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Oxide semiconductors have been considered as promising channel materials for thin-film transistors (TFTs). However, device reliability against negative-bias illumination stress (NBIS) remains a critical issue that hampers further applications. In this article, the effect of the bandgap widening on the NBIS stability of the oxide TFTs is investigated by simply incorporating the wide bandgap Ga2O3 into In2O3. It is found that there is a tradeoff between the mobility and the NBIS stability. When the Ga2O3 concentration increases from 10 wt% to 45 wt%, the mobility decreases from 22.9 to 5.5 cm2·V−1·s−1, while the ${V}_{ \mathrm{\scriptscriptstyle ON}}$ shift ( $\Delta {V}_{ \mathrm{\scriptscriptstyle ON}}$ ) under 3600 s NBIS improves from −17.8 to −1.6 V. The great improvement of the NBIS stability with increasing Ga2O3 concentration is ascribed to the bandgap widening. After incorporating a certain amount of Ga2O3 into In2O3, the energy difference between the conduction band minimum (CBM) and the ${V}_{O}$ state is larger than the maximum photon energy of the white LED, resulting in lesser sensitivity to the incident white light.

Polymer/oxide hybrid thin films, which have excellent electrical and mechanical performance, can be effectively fabricated through the sol-gel process, showing great potential in the future printed electronics. However, gelation of polymer/oxide ink systems can easily occur during a thermal process in which case capillary stress can lead to the crack of printed films due to the long period of stress accumulation. To solve this problem, the effect of different solvent systems on formed PAM/ZrOx hybrid films, which were printed by piezoelectric printing, was studied in this paper, including single solvent systems of glycol and binary solvent systems of glycol and water. The result showed that the microstructure characteristics and mechanical properties of hybrid nanostructures formed in different solvent systems varied significantly, and crack behavior can be regulated by simply adjusting the water volume ratio of the solvent system. The crack formation was significantly inhibited when the water volume ratio reached 25%.

In this work, a sky-blue luminescent down-shifting (LDS) layer bis[(4,6-difluorophenyl)-pyridinato-N,C2′]c(picolinate)iridium(III) (FIrpic) was inserted between tetraphenyldibenzoperiflanthene (DBP) and MoO3 as UV-screen and sensitizer for small molecule DBP/C60 based planar heterojunction (PHJ) solar cells. With 8-nm FIrpic the short circuit current (Jsc) and power conversion efficiency (PCE) of the device are enhanced by 28% and 15%, respectively, probably originating from the re-absorption of the photons emitted from FIrpic. The Voc linearly increases over 1-nm FIrpic, ascribed to the deeper HOMO level of FIrpic than DBP, while the fill factor continuously declines from 3- to 10-nm FIrpic. The EQE spectra prove that the Jsc is mainly contributed by the photocurrent generated in DBP and C60 layers. When the FIrpic thickness is 8 nm, the film surface is very uniform with the smallest water contact angle. The impedance spectroscopy demonstrates that the device resistance gradually increases from 4.1×104 Ω (without FIrpic) to 4.6×104 Ω (with 10-nm FIrpic) with the FIrpic thickness rise, simultaneously the device transits from the insulating state into the conductive state faster for the thin FIrpic layer than the thick layer.

The mixed cohosts of electron transport host (E-host): 4,40-bis(carbazol-9-yl)biphenyl (CBP) have been comparatively investigated for an efficient green fluorescent organic light emitting diode (OLED) doped with a thermally activated delayed fluorescence (TADF) emitter (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN). The E-host:CBP systems significantly enhance the electroluminescent (EL) properties. After doping E-host, the lifetime of the emissive layer decreases and the surface becomes smoother, together with the impedance decreases for one magnitude and the hole-injection depresses. The charge balance and improved interface both contribute to the EL performance enhancement. Here we develop a universal mixed host system suitable to most of emitters.

Tungsten oxide (WO3) electrochromic devices have attracted a lot of interest in the energy conservation field and have shown a preliminary application potential in the market. However, it is difficult to quantitatively direct experiments with the existing electrochromic theoretical models, which can restrict the further development of electrochromism. Here, an electrochromic physical simulation model of WO3 films was built to solve the above problem. Experimentally, the actual electrochromic kinetics of WO3 in the LiClO4/propylene carbonate electrolyte was determined as a continuous electron-transfer process by cyclic voltammetry measurement and X-ray photoelectron spectroscopy analysis. Theoretically, the continuous electron-transfer process, Li+-ion diffusion process, and the transmittance change process were described by a modified Butler-Volmer equation, Fick's law, and charge versus coloration efficiency/bleaching efficiency coupling equation, respectively. The comparisons between theoretical and experimental data were conducted to verify this model. The shape of the simulated current curves was basically consistent with that of experiments. Besides, the difference of transmittance between the simulation and experiments was less than 8%. The difference between theory and experiment was attributed to the influence of the electric double layer and the actual reaction interface. The success of the simulation was attributed to the accurate description of the electrochromic process by continuous electron-transfer kinetics. This model can be applied in the research of electrochromic mechanisms, experimental result prediction, and novel device development due to its clear physical nature.

Manipulating the molecular orbital properties of excited states and the subsequent relaxation processes can greatly alter the emission behaviors of luminophores. Herein we report a vivid example of this, with luminescence conversion from thermally activated delayed fluorescence (TADF) to ultralong room-temperature phosphorescence (URTP) via a facile substituent effect on a rigid benzothiazino phenothiazine tetraoxide (BTPO) core. Pristine BTPO with multiple heteroatoms shows obvious intramolecular charge transfer (ICT) excited states with small exchange energy, featuring TADF. Via delicately functionalizing the BTPO core with peripheral moieties, the excited states of the BTPO derivatives become a hybridized local and charge transfer (HLCT) state in the S1 state and a local excitation (LE) dominated HLCT state in the T1 state, with enlarged energy bandgaps. Upon dispersion in a polymer matrix, the BTPO derivatives exhibit a persistent bright green afterglow with long lifetimes of up to 822 ms and decent quantum yields of up to 11.6%., The decoration of a BTPO core results in a change in the luminescence nature from TADF to URTP. The phosphors in an amorphous PMMA matrix showed monomeric URTP with phosphorescence lifetimes of up to 822 ms and quantum yields of up to 11.6%.

Drop-on-demand printing is a noncontact direct patterning and rapid manufacturing printing technology which shows considerable potential in future display manufacturing. Metal oxides are an important kind of functional material in thin-film transistors, which are the core component of active matrix display technology, and thus printing a high-quality metal oxide functional layer is of great importance. In this feature article, we focused on the current progress in one of the foundations of drop-on-demand printing technology-the ink system. We explained the basic principles of a metal oxide ink system for printed electronics and summarized the applications of several kinds of ink systems in thin film transistor printing. Meanwhile, we also summed up problems that printed thin film transistors are facing as well as the corresponding solutions from the aspect of ink systems.

Organic electron-transport materials are an essential component to boost performances and stability of organic light-emitting diodes. We present a robust organic electron-transport compound 3-(6-(3-(4,6-bis(4-biphenylyl)-1,3,5-triazin-2-yl)phenyl)pyridin-2-yl)phenyldiphenylphosphine oxide by facilely coupling the triphenylphosphine oxide moiety to the 2-phenyl-4,6-bis(4-biphenylyl)-1,3,5-triazine unit via a 2,6-pyridinylene linker. It is well soluble in weakly polar solvents and possesses a high T g of 123 °C with an exceptional T d » 470 °C at 1% weight loss and deep HOMO/LUMO levels of ca. −6.45/−3.06 eV. The phosphorescent spectrum measured in solid state at 77 K reveals a notable triplet energy of 2.88 eV. n-Doping with 8-hydroxyquinolatolithium (Liq) produces the electron mobility value of 4.66×10−5–3.21× 10−4 cm2 V−1 s−1 @(2–5)× 105 V cm−1. Moreover, the contrasting solubility of the bromo reaction intermediate and the new compound in alcoholic solvents facilitates separation. The characterizations of bottom- and top-emission green phosphorescent OLEDs involving this single Liq-doped electron-transport layer reveal long stability. In particular, the latter provides outstanding performances with 77.4 cd A–1 (corresponding to an EQE of 18.7%) and 86.8 lm W–1 @ca. 1000 cd m−2, based on the green emitter bis(2-phenylpyridine)(2-(4-methyl-3-phenylphenyl)pyridine)iridium(III). Moreover, driven by a constant current for ca. 640 h, the initial luminance of 1000 cd m–2 appears almost no decay .

For light-emitting polymers with a deep highest occupied molecular orbital energy level used for polymer light-emitting diodes (PLEDs), the hole injection barrier and hole transport of the anode buffer layer are of vital importance for optimizing electroluminescent performance. In this study, high-work-function hole injection layers with nanotextures were achieved by modifying poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with a perfluorinated ionomer (PFI) and

For inkjet-printed organic light-emitting diodes, it is critical to obtain a homogeneous small molecule-based emitting film. In contrast to the conventional strategy of utilizing mixed solvents, we have successfully inkjet printed a binary electrophosphorescent emitter with a single solvent. The binary emitter consists of a new host material 3-(3,6-di-t-butylcarbazol-9-yl)-3′-(2-(4-t-butylphenyl)benzoimidazol-1-yl)-[1,1′-biphenyl], and an iridium complex dopant bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)-iridium(III) (Ir(MDQ)2(acac)). Compatible with Ir(MDQ)2(acac), the newly developed host is highly soluble and amorphous with a glass transition temperature of 137 °C upon cooling from the melt. The inkjet printability and film morphology of the emitting layer are strongly dependent both on the substrates and the solvents. With o-dichlorobenzene (o-DCB) as the single solvent, and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(p-butylphenyl))diphenylamine)] (TFB) as the hole transporting layer, a uniform emitter film morphology without any coffee ring is obtained. The phosphorescent OLED with the inkjet-printed emitter yields a maximum current efficiency of 17.89 cd A−1, comparable to that of Ir(MDQ)2(acac)-based OLEDs with a spin-cast emitter.

The development of sustainable routes for the synthesis of metal organic frameworks (MOFs) is very important because of the wide applications of MOFs on a large scale in the fields of adsorption, separation, and catalysis. ZIF-8, a zinc-based zeolitic imidazolate framework (ZIF), was first prepared following a solvent-free method from zinc acetate and denoted as ZIF-8-DGUT. The synthesis was conducted with the addition of an appropriate amount of sodium hydroxide (NaOH) powder before fully grinding, and the synthesis was accomplished at mild temperature at 343 K for 24 h. This strategy provided a practical method for the production of ZIF materials.

The biggest challenge for metal oxide-based hydrogen gas sensors is to eliminate the interference of other gases. Zeolitic imidazolate frameworks, such as ZIF-8, are ideal filters for large molecules because of their fixed pore size. In this paper, the green and economic synthesis method of dry gel conversion (DGC) was first utilized to convert the surface of ZnO into ZIF-8 with 2-methylimidazole (MeIM) as ligand, and a ZnO@ZIF-8 core–shell structure was successfully constructed. TEM et al. characterizations indicated that the thickness of ZIF-8 shell was effectively controlled by the initial MeIM/ZnO molar ratio. The synthesized ZnO@ZIF-8 showed an excellent selective response for H2 (2.4 to 100 ppm and 0.9 to 50 ppm) over toluene (2.6 to 10 ppm and 0.3 to 1 ppm) at an optimal heating voltage of 5 V as the initial MeIM/ZnO ratio was 0.2, which confirmed that ZnO@ZIF-8 prepared by DGC method showed excellent promise for a practical application as a selective H2 detector.

The large-sized polycrystalline stannous oxide (SnO) synthesized by a sol–gel method was found to have attractive crystal structural properties and thermo-oxidative stability. The present work describes the thermal stability performance of this large-size polycrystalline material at different temperatures in air. The obtained results showed a systematic oxidation from SnO to stannic oxide (SnO2) in the range of 450–1300 °C and SnO completely oxidized to SnO2 above 900 °C, but it was in a stable state under 450 °C. Other than this, the lattice parameters of SnO and SnO2 also changed slightly at different temperatures. For instance, the lattice parameters of SnO changed from a = b = 3.799 nm and c = 4.841 nm (at room temperature (RT)) to a = b = 3.803 nm and c = 4.838 nm at 300 °C, and the lattice parameters of SnO2 also changed at 600 °C, 700 °C, and 1000 °C. In addition, the present work also explored the effect of oxygen on the crystal surface at RT. The obtained results showed a slow oxidation process from SnO to SnO2 by being in contact with oxygen. Only 6.4% of SnO on the crystal surface was oxidized after one week, which indicated that SnO was a steady-state material. The obtained large-sized polycrystalline SnO, which exhibited excellent thermo-oxidative stability might be a good candidate as a p-type oxide material for photoelectric applications.

Inkjet printing of environmentally friendly functional nanomaterials for high performance indium–gallium–zinc oxide (IGZO) thin film transistors (TFTs) is highly in demand for the development of inexpensive and green electronics. However, it remains challenging to obtain nanomaterial inks with desirable physicochemical properties for inkjet printing and finally to achieve homogeneous in-plane patterns. Here, we present biodegradable and uniform cellulose dielectric films for high performance IGZO TFTs via inkjet printing. Firstly, an oxidized cellulose nanofibril (CNF) was selected due to its stable dispersion in water, and additives were added to obtain CNF ink suitable for our printing system. Moreover, it was found that adding additives also increased the interactions inside the solution, so the obtained CNF ink exhibited a gel-like behavior with a rapidly increasing viscosity after high-speed shearing. Such behavior was defined as fast-self-gelation properties, which were beneficial for improving the uniformity of the printed films by inhibiting the outward capillary flow. Based on these properties, we further added surfactants to regulate the internal flow, and then obtained a homogeneous morphology. Besides the excellent uniformity, the prepared CNF film was a candidate for transparent dielectrics, with excellent transparency (above 95%) and a low leakage current density (3.68 × 10−6 A cm−2). Finally, IGZO-TFTs with a mobility of more than 10 cm2 V−1 s−1 and an on/off current ratio of higher than 5 × 104 were fabricated using the printed CNF films as dielectrics, thus shedding light on the use of CNF dielectrics obtained by inkjet printing for the fabrication of high-performance, inexpensive, and environmentally friendly electronics.

Stable radicals are challenging to prepare due to their intrinsic high reactivity. Herein, three trisphenolamine radicals were readily synthesized and exhibited unexpected thermal/electrochemical stability and semiconductor property. These three nitroxide radicals could be considered as a class of aromatized nitro groups or HNO3 derivatives. The closed-shell nitro-like and open-shell nitroxide resonance structure contribute to their outstanding stability. Furthermore, the tunable ground states, extremely low band gap and p-type charge transport properties were systematically investigated. More importantly, the work presents the concept of aromatic inorganic acid radical (AIAR) and aggregation-induced radical (AIR) mechanism to understand the intrinsic structure-property relationship of these radicals. In addition, we provide a novel strategy for the design of stable and low bandgap radicals for organic electronics, magnetics, spintronics, etc.

Back-channel-etch (BCE) thin-film transistors (TFTs) with the stacked channel of sputtering InZnO (IZO) and spray coating ZnSnO (ZTO) were fabricated. The spray-coated ZTO film shows an ideal surface morphology with technical optimization. The TFT combined with this ZTO film as barrier exhibits superior performance with higher output current, lower threshold voltage, and higher effective electron mobility. Moreover, the short channel effect is less severe with spray-coated ZTO, and the TFTs also demonstrated excellent stability with voltage shift of less than 1.0 V under positive bias temperature stress (PBTS) and negative bias temperature stress (NBTS) with stress time as 7200 s (temperature as 60°). These results indicate that spray-coated ZTO films as a barrier in BCE structure is feasible for the mass production of oxide semiconductor-based TFT backplanes.

Amorphous indium gallium zinc oxide is a popular semiconductor candidate for amorphous oxide semiconductor thin-film transistors in the field of flat-panel display. However, the existence of gallium component restricts the enhancement of mobility dramatically. In this study, we report a new praseodymium (Pr) dopant as a stabilizer in amorphous indium zinc oxide semiconductor (IZO) with high mobility and stability. Meanwhile, the PrIZO TFTs were fabricated to investigate the effects of Pr on electrical properties, stability and aging effect. The optimal PrIZO TFT exhibited a desired performance with a saturation mobility (μsat) of 25.8/32.6 cm2 V−1 s−1, an Ion/Ioff ratio of 3.5 × 107/5.4 × 107, a subthreshold swing value of 0.14/0.13 V dec−1 and a threshold voltage (Vth) of 2.9/2.1 V, respectively, before and after an air environment storage period of 90 days without passivation layer, which exhibits lower sensitivity of the channel region to oxygen/moisture from the atmosphere than IZO TFT. XRD analysis revealed that the Pr dopant had no effect on the amorphous state of IZO thin film with annealing up to 400 °C. XPS analyses suggested that the fraction of oxygen vacancy subpeak decreased significantly with Pr incorporated into IZO. The μ-PCD decay analyzation and the subgap density of states indicate that acceptor-like trap states induced by Pr ions lead to the suppression of ambient-induced excess carrier in conduction band. This work is anticipated to provide a kind of reliable stabilizer for amorphous oxide semiconductor without deteriorating mobility significantly.

A polymer-doped ink system was applied to a printed InOx thin film transistor (TFT), and enhancement mode devices were obtained with an appropriate polymer doping amount. As the polymer doping conc...

Tungsten doped stannic oxide transparent conductive thin films (W-doped SnO2) have been prepared via a solution process. We use stannous chloride, preoxotungstic acid (PTA), hydrogen peroxide and anhydrous ethanol to prepare precursor solution which is stable and colorless. By investigating the effects of tungsten doping ratio and annealing temperature on properties of tungsten doped stannic oxide films, it is found that the amounts of pores on surface can be reduced by increasing annealing temperature. Amorphous SnO2 begins to transform into crystalline SnO2 when annealed at 300 °C. The resistivity of 2 at.% W-doped SnO2 achieves 2.94 × 10−2 Ω cm annealed in air at 500 °C. The transmittance of W-doped SnO2 films (around 87%) is better than that of pure SnO2 films (around 83%) in visible range contrasted with blank quartz glass. The optical band gaps of both doped and pure SnO2 films are over 3.7 eV.

The realization of high-performance blue polymer light-emitting diodes typically requires a hole transport layer to facilitate hole injection, primarily due to the deep highest occupied molecular orbital (HOMO) energy levels of the blue light-emitting polymers. However, the widely-used hole transport layers (HTLs) are prone to induce exciplex with longer wavelength emission when cooperating with those n-type blue-light-emitting layers, due to the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels offsets. To avoid formation of exciplex and improve device performance of blue light-emitting, we employed two hole-transport layers consisting of a cross-linkable poly(indenofluorene-co-triphenylamine) copolymer and an additional poly(9-vinylcarbazole) (PVK) layer. The devices with dual HTLs have an enhanced luminous efficiency of 7.67 cd A−1 while keep the electroluminescent spectrum identical to the device based on PVK devices. The resulting blue light-emitting device based on such two-layer HTL exhibited remarkable stability, with luminous efficiency remained about 6.6 cd A−1 at a luminance of 10000 cd m−2. Our results shown that the dual HTLs device structure is a promising strategy for constructing high performance solution-processed blue polymer light-emitting diodes.

Amorphous oxide semiconductors are promising for their use in thin-film transistor (TFT) devices due to their high carrier mobility and large-area uniformity. However, their commercialization is limited by the negative gate bias stress experienced under continuous light illumination. Here, we report an approach to improve the negative bias illumination stress (NBIS) stability of amorphous oxide semiconductors TFTs by using lanthanide-doped indium oxide semiconductors as the channel layer. The effect of different lanthanide dopants on performances of solution-processed Ln:In2O3 TFTs are investigated. All lanthanides exhibit strong suppression of oxygen vacancy, which shift the Von from −13.5 V of pure In2O3 TFT to −1~1 V of Ln:In2O3 TFTs (except Ce). However, only Pr:In2O3 and Tb:In2O3 TFTs exhibit much better NBIS stability with same ΔVon of −3.0 V, compared to much higher ΔVon of −7.9~−15.6 V for other Ln:In2O3 TFTs. Our comprehensive study reveals that praseodymium and terbium act as a blue light down-conversion medium with low charge transfer transition energy for lowing photosensitivity of oxide semiconductors.

We report the effects of ultraviolet (UV) irradiation and storage on the performance of ZnO-based inverted quantum-dot light-emitting diodes (QLEDs). The effects of UV irradiation on the electrical properties of ZnO nanoparticles (NPs) were investigated. We demonstrate that the charge balance was enhanced by improving the electron injection. The maximum external quantum efficiency (EQE) and power efficiency (PE) of QLEDs were increased by 26% and 143% after UV irradiation for 15 min. In addition, we investigated the storage stabilities of the inverted QLEDs. During the storage period, the electron current from ZnO gradually decreased, causing a reduction in the device current. However, the QLEDs demonstrated improvements in maximum EQE by 20.7% after two days of storage. Our analysis indicates that the suppression of exciton quenching at the interface of ZnO and quantum dots (QDs) during the storage period could result in the enhancement of EQE. This study provides a comprehension of the generally neglected factors, which could be conducive to the realization of high-efficiency and highly storage-stable practical applications.

Nickel (Ni) is one of the most common heavy metals. In this study, nano-sized magnetic ion-imprinted polymers (MIIPs) were synthesized using chitosan as the functional monomer, and used for selective adsorption and recovery of Ni(II) from solutions. The results showed MIIPs possessed high sorption selectivity for Ni(II), and the change in pH (5.0–9.0) exerted insignificant influence on the ion adsorption, allowing almost complete elution and recovery of adsorbed Ni(II) ions by using 0.5% EDTA-Na solution. Moreover, the sorption capacity of the recycled MIIPs decreased by only about 10% after 15 adsorption-desorption cycles. The time required for establishing the adsorption equilibrium was less than 1 h. The sorption process was predominant and endothermic, and could be well described by both Langmuir isotherm model and pseudo-second-order kinetic model. Therefore, the synthesized MIIPs was a suitable adsorbent for highly selective, fast and efficient removal and recovery of low-concentration Ni(II) ions from wastewaters.

Flexible thin-film transistors with high current-driven capability are of great significance for the next-generation new display technology. The effect of a Cu-Cr-Zr (CCZ) copper alloy source/drain (S/D) electrode on flexible amorphous neodymium-doped indium-zinc-oxide thin-film transistors (NdIZO-TFTs) was investigated. Compared with pure copper (Cu) and aluminum (Al) S/D electrodes, the CCZ S/D electrode changes the TFT working mode from depletion mode to enhancement mode, which is ascribed to the alloy-assisted interface layer besides work function matching. X-ray photoelectron spectroscopy (XPS) depth profile analysis was conducted to examine the chemical states of the contact interface, and the result suggested that chromium (Cr) oxide and zirconium (Zr) oxide aggregate at the interface between the S/D electrode and the active layer, acting as a potential barrier against residual free electron carriers. The optimal NdIZO-TFT exhibited a desired performance with a saturation mobility ( μ sat ) of 40.3 cm 2 ·V -1 ·s -1 , an I on / I off ratio of 1.24 × 10 8 , a subthreshold swing (SS) value of 0.12 V·decade -1 , and a threshold voltage ( V th ) of 0.83 V. This work is anticipated to provide a novel approach to the realization of high-performance flexible NdIZO-TFTs working in enhancement mode.

In this paper, the effects of annealing temperature and other process parameters on spin-coated indium oxide thin film transistors (In2O3-TFTs) were studied. The research shows that plasma pretreatment of glass substrate can improve the hydrophilicity of glass substrate and stability of the spin-coating process. With Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analysis, it is found that In2O3 thin films prepared by the spin coating method are amorphous, and have little organic residue when the annealing temperature ranges from 200 to 300 &deg, C. After optimizing process conditions with the spin-coated rotating speed of 4000 rpm and the annealing temperature of 275 &deg, C, the performance of In2O3-TFTs is best (average mobility of 1.288 cm2&middot, V&minus, 1&middot, s&minus, 1, Ion/Ioff of 5.93 &times, 106, and SS of 0.84 V&middot, dec&minus, 1). Finally, the stability of In2O3-TFTs prepared at different annealing temperatures was analyzed by energy band theory, and we identified that the elimination of residual hydroxyl groups was the key influencing factor. Our results provide a useful reference for high-performance metal oxide semiconductor TFTs prepared by the solution method.

In recent years, significant efforts have been devoted to the research and development of spin-coated Al2O3 thin films, due to their large band gaps, high breakdown voltage and stability at high annealing temperature. However, as the alumina precursor has a large surface energy, substrates need to be treated by plasma before spin coating. Therefore, to avoid the expensive and process-complicated plasma treatment, we incorporated zirconium nitrate into the aluminum nitrate solution to decrease the surface energy of the precursor which improve the spreadability. Then, the electrical performances and the surface morphologies of the films were measured. For comparison, the pure Al2O3 films with plasma treatments were also prepared. As a result, after low temperature annealing (200 &deg, C), the relative dielectric constant of Zr&ndash, AlOx spin-coated thin-film MIM (Metal-Insulator-Metal) devices can reach 12 and the leakage current density is not higher than 7.78 &times, 10&ndash, 8 A/cm2 @ 1 MV/cm when the concentration of zirconium nitrate is 0.05 mol/L. The Aluminum oxide film prepared by zirconium doping has higher stability and better electrical properties than the pure films with plasma treatments and high performance can be attained under low-temperature annealing, which shows its potential application in printing and flexible electronic devices.

The fully inkjet-printed top-gate metal–oxide thin-film transistors (TFTs) with excellent electrical performance are realized with the gate dielectric layer of scandium zirconium oxide (Sc1Zr1O x ). It is found that adding of nitrate-based scandium oxide (ScO x ) precursor into the chloride ligand-based zirconium oxide (ZrO x ) precursor will reduce the corrosivity of the mixed solution, and the incorporation of Zr ions into ScO x will suppress the hydrogen-ion migration and eliminate the acceptor-like traps in pure ScO x . The fully printed indium gallium oxide (InGaO) TFTs based on Sc1Zr1O x dielectric exhibited an average mobility of 10.8 cm $^{{2}} \text{V}^{\vphantom {R^{'}}-{1}} \cdot \text{s}^{-{1}}$ , a highest mobility of 12.9 cm $^{{2}} \cdot \text{V}^{-{1}} \cdot \text{s}^{-{1}}$ , negligible hysteresis, and excellent stability under both the negative and positive bias stresses. In addition, a resistor-loaded inverter was fabricated using a fully printed InGaO TFT, which exhibited the full swing characteristics and a maximum gain of 5 at 2 V.

Recently, the performance of thin-film transistors (TFTs) with amorphous oxide semiconductors (AOSs) has been substantially improved. However, the device reliability under negative bias illumination/temperature stress (NBI/TS) remains a critical issue. Herein, a Cd and Sc co-doped In2O3 semiconductor (CdScInO) is developed for improving the NBI/TS stability of TFTs. The mobility, subthreshold swing, and on/off ratio of the CdScInO TFT are 15.9 cm2 V−1 s−1, 89 mV dec−1 and ∼107, respectively. More interestingly, the CdScInO TFTs exhibit excellent stability under NBTS at 80 °C or under NBIS with red light or green light illumination, while a threshold voltage shift of only −0.91 V is observed under NBIS with blue light illumination for 3600 s. First-principles calculations show that the Cd dopants cause the formation of holes, which can be bound with oxygen vacancies (VOs) to form Cd–VO pairs. Furthermore, the density of states near the valence band maximum decreases due to the upward repulsion between the O p states and the Cd d states. Thus, the activation of VO or electron donor defects is suppressed, which explains the NBI/TS stability improvement for CdScInO TFTs.

Solution-processed oxide dielectrics are widely studied as alternatives to SiO2, SiNx in thin film transistors for high capacitance and low energy consuming. However, it's still a challenge to achieve high quality of solution-processed oxide dielectrics TFT by low-temperature post-treatment. Here, an effective strategy is proposed to evaluate low temperature solution-processed ZrO2 TFT in terms of uniformity, film density and electrical performance by employing TG/DSC, drop analyzer, XRR and a novel μ-PCD measurement. Particularly, μ-PCD measurement provides valuable information on homogeneity and defect level. The optimized device with ZrNO3 as dielectric precursor and ethyl alcohol as solvent through spin coating process annealed at 200°C shows a saturation mobility of 8.6 cm2V-1S-1, Ion/Ioff ratio about 1.1×106, subthreshold swing about 334 mV/decade with a low leakage current density of 5×10-5 A/cm2 at 10V. This article offers a convenient way for precursor optimization towards low leakage current and high homogeneity solution-processed oxide dielectrics for TFT devices.

The balance between electron and hole injection is critical for obtaining high efficiency in quantum dot light-emitting diodes (QLEDs). Herein, 1,4-dioxane was employed as a solvent for poly(9-vinylcarbazole) (PVK) in stepwise co-HTL (HTL: hole transport layer)-based red QLEDs with poly[bis(4-phenyl)(4-butylphenyl)amine] (poly-TPD)/PVK, enabling a 41.5% enhancement in external quantum efficiency (EQE) compared to that of the control device without a PVK layer. Based on the high-performance co-HTL device, the blue phosphorescence dye bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (FIrpic) was incorporated into PVK for further improving the device efficiency. Consequently, at a blend ratio of 10 : 2 in volume, the co-HTL QLED with a mixed PVK : FIrpic layer showed the highest maximum current efficiency (CEmax) of 18.2 cd A−1 and EQEmax of 12.2%, which was 30% and 28.4% higher than that of the co-HTL device without the FIrpic mixture, respectively. Compared to the control device with only poly-TPD as the HTL, the luminous efficiency nearly doubled. The substantial performance improvements are mainly attributed to the stepwise energy level alignment of the HTLs, uniform morphology of the PVK:FIrpic films obtained from the orthogonal solvent 1,4-dioxane, and efficient nonradiative energy transfer (NRET) from PVK : FIrpic (10 : 2) to the QDs. Thus, this study offers a new practical method to promote the performance of QLEDs and eventually their commercial use in display and lighting applications.

In electrochemistry, the carbazole is generally coupled to dimer but not to polymer. This work has reported that organic electropolymerization (OEP) of 4,4',4″-tri(N-carbazolyl)triphenylamine (TCTA) would form a high cross-linked carbazole polymer by its high activity/reversibility and a synchronous viscosity control. It has significantly improved the OEP film quality of both hole-transporting and electroluminescent layers in organic light-emitting diodes. As a result, the conductivity and power efficiency of the organic light-emitting diodes with TCTA are eight and four times of that without TCTA. A prototype display device with a 1.7 in. monochrome passive matrix of 58 ppi under the driving chip is successfully fabricated with accurate pixel size and uniform electroluminescence, which shows a great potential of OEP in the electroluminescent application.

In this paper, zirconium&ndash, aluminum&ndash, oxide (ZAO) dielectric layers were prepared by a solution method with intent to combine the high dielectric constant with a low leakage current density. As a result, dielectric layers with improved electrical properties as expected can be obtained by spin-coating the mixed precursor. The chemical and physical properties of the films were measured by thermogravimetric differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and a UV spectrometer. It is observed that the oxygen defects and the hydroxide in the films are reduced with the addition of high-bond-energy zirconia, while the films can remain large optical bond gaps thanks to the presence of alumina. The metal-insulator-metal (MIM) devices were fabricated, and it was seen that with a molar ratio of Zr:Al = 3:1 and an annealing temperature of 500 &deg, C, the dielectric layer afforded the highest dielectric constant of 21.1, as well as a relatively low leakage current of 2.5 106 A/cm2@1MV/cm. Furthermore, the indium&ndash, gallium&ndash, zinc oxide thin-film transistors (IGZO-TFTs) with an optimal ZAO dielectric layer were prepared by the solution method and a mobility of 14.89 cm2/Vs, and a threshold voltage swing of 0.11 V/dec and a 6.1 106 on/off ratio were achieved at an annealing temperature of 500 &deg, C.