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The interface effect is one of the most important factors that strongly affect the structural transformations and the properties of nano-/submicro-crystals under pressure. However, characterization of the granular boundary changes in materials is always challenging. Here, using tetrakaidecahedral Zn2SnO4 microcrystals as an example, we employed alternating current impedance, X-ray diffraction methods and transmission electron microscopy to elucidate the effect of the interface on the structure and electrical transport behavior of the Zn2SnO4 material under pressure. We clearly show that grain refinement of the initial microcrystals into nanocrystals (approximately 5 nm) occurs at above 12.5 GPa and is characterized by an anomalous resistance variation without a structural phase transition. A new phase transition pathway from the cubic to hexagonal structure occurs at approximately 29.8 GPa in Zn2SnO4. The unexpected grain refinement may explain the new structural transition in Zn2SnO4, which is different from the previous theoretical prediction. Our results provide new insights into the link between the structural transition, interface changes and electrical transport properties of Zn2SnO4. [ABSTRACT FROM AUTHOR]

Development of ternary metal oxide (TMO) based electron transporting layer (ETL) for perovskite solar cell open a new approaches toward efficient a unique strategy for solid state dye-sensitized solar cells (ssDSSCs). In the present investigation, highly porous zinc tin oxide (Zn2SnO4) scaffold nanofibers has been synthesized by electrospinning technique and successfully used for methyl ammonium lead halide (CH3NH3PbI3) perovskite sensitized solid state solar cells. The fabricated optimized perovskite solar cell devices exhibited 7.38% power conversion efficiency (PCE) with open circuit voltage (VOC) 0.986 V, current density (JSC) = 12.68 mAcm-2 and fill factor (FF) 0.59 under AM 1.5 G sunlight (100 mWcm−2) which is higher than Zn2SnO4 nanoparticle (η = 2.52%) based perovskite solar cells. This improvement is achieved due to high porosity of Zn2SnO4 nanofibers and high crystallinity of the nanofibers synthesized at 700 °C. These results are remarkably higher than reported perovskite solar cells based on such type of ternary metal oxide ETLs. [ABSTRACT FROM AUTHOR]

Solution based deposition has been recently considered as a viable option for low-cost flexible electronics. In this context research efforts have been increasingly centred on the development of suitable solution-processed materials for oxide based transistors. Nevertheless, the majority of synthetic routes reported require the use of toxic organic solvents. In this work we report on a new environmental friendly solution combustion synthesis route, using ethanol as solvent, for the preparation of indium/gallium free amorphous zinc-tin oxide (ZTO) thin film transistors (TFTs) including AlOx gate dielectric. The decomposition of ZTO and AlOx precursor solutions, electrical characterization and stability of solution processed ZTO/AlOx TFTs under gate-bias stress, in both air and vacuum atmosphere, were investigated. The devices demonstrated low hysteresis (ΔV = 0.23 V), close to zero turn on voltage, low threshold voltage (VT = 0.36 V) and a saturation mobility of 0.8 cm2 V−1 s−1 at low operation voltages. Ethanol based ZTO/AlOx TFTs are a promising alternative for applications in disposable, low cost and environmental friendly electronics. [ABSTRACT FROM AUTHOR]

We report on improved device performances of solution-processed zinc tin oxide (ZTO) thin film transistors (TFTs) using a graphene interlayer between an Al electrode and ZTO. The ZTO TFTs with a high-temperature annealing process at 600 °C show improved output characteristics compared to ones with annealing at relatively lower temperatures, which can be attributed to the reduced impurity and condensed surface state. The ZTO TFTs using the Ohmic contact of the graphene/Al electrode (G-ZTO TFTs) with an optimized annealing process exhibited a good saturation mobility of (6.96 cm2 V·s)−1, a subthreshold slope of 1.52 V dec−1 and a threshold voltage shift toward a negative bias direction. The improvement of device performances of G-ZTO TFTs can be contributed to good Ohmic contact formation by using graphene inserted between the ZTO active layer and the Al electrode. [ABSTRACT FROM AUTHOR]

We deposited InZnSnO (IZTO) channel layers, where indium (In) composition was controlled from 0 to 28.4 at %. Oxide thin-film-transistors (TFTs) based on these IZTO channels have shown a remarkable field effect mobility of > 30 cm2 V−1 s−1, low sub-threshold swing and good stability, compared to the ZTO TFTs. From x-ray photoelectron spectroscopy results, we found that the IZTO film containing 19.4 at % In showed enhanced intensity from the anomalous Sn2+ related chemical bonding. The incorporation of In elements promotes the formation of Sn2+-O2− binding in the IZTO films, resulting in compensation for the oxygen vacancies in the IZTO films. Thus, moderate incorporation in the ZTO led to improved stability and high field effect mobility simultaneously. [ABSTRACT FROM AUTHOR]

Nonvacuum and photolithography-free copper (Cu) films were prepared by reverse offset printing. The mechanical, morphological, structural, and chemical properties of the Cu films annealed at different temperatures were examined in detail. The Ostwald ripening-induced coalescence and grain growth in the printing Cu films were enhanced with increasing annealing temperature in N2 ambient up to 400 °C. Simultaneously, unwanted chemical impurities such as oxygen, hydrogen, and carbon in the Cu films decreased as the annealing temperature increased. The high electrical conductivity (∼6.2 μΩ·cm) of the printing Cu films annealed at 400 °C is attributed to the enlargement of the grain size and reduction of the incorporation of impurities. A printing Cu film was adopted as a source/drain (S/D) electrode in solution processable zinc tin oxide (ZTO) field-effect transistors (FETs), where the ZTO film was prepared by simple spin-coating. The ZTO FETs fabricated at a contact annealing temperature of 250 °C exhibited a promising field-effect mobility of 2.6 cm(2)/(V s), a threshold voltage of 7.0 V, and an ION/OFF modulation ratio of 2 × 10(5).

We investigated the bias stress stability of solution-processed indium–gallium–zinc-oxide thin-film transistors (IGZO TFTs) using zinc–tin-oxide (ZTO) as the etch-stopper layer, the so-called dual-active-layered ZTO/IGZO TFT (DALZI TFT). The DALZI TFT can use a low-cost back-channel-etch structure because of the high chemical stability of the upper ZTO layer. The DALZI TFT exhibited only a threshold voltage shift of −1.86 V under negative bias illumination stress (NBIS) conditions (stress time = 1000 s), while the unpassivated IGZO TFT suffered from a threshold voltage shift of −19.59 V under NBIS conditions (stress time = 1000 s). The superior bias stress stability of the DALZI TFT is attributed not only to the densification effect by the multi-stacking process but also to the lower sensitivity to ambient gases (e.g., oxygen and water vapour) due to the low oxygen vacancy in the upper ZTO layer. [ABSTRACT FROM AUTHOR]

Highly uniform thin-films of zinc-indium-tin oxide (ZITO) semiconductors were formed using solution process with wet-annealing at a low temperature of 250 °C. The solution-processed ZITO thin-film transistors with a top-gate staggered structure were fabricated to exhibit field-effect mobility of 2.04 ± 0.28 cm2/Vs at saturation region, threshold voltage (Vth) of 2.15 ± 0.75 V, subthreshold slope of 0.27 ± 0.14 V/dec. and excellent reliability (ΔVth = -4.35 V) for negative bias temperature illumination stress. Based on the performance, a 10.1 in. full-color liquid crystal display was demonstrated by the optimized full photolithography process. [ABSTRACT FROM AUTHOR]

Thin film transistors (TFTs) with Si incorporation in zinc tin oxide (ZTO) channel layer were fabricated using a sol-gel process, and the effect of Si incorporation in ZTO systems was investigated with respect to optical, structural, and electrical properties. The Si effectively controlled the generation of the oxygen vacancies examined by x-ray photoelectron spectroscopy, which affected the electrical properties of the silicon zinc tin oxide (SZTO) TFTs. As the Si concentration increased in the ZTO systems, the threshold voltage shifted in the positive direction, the on-off current ratio increased due to the effective reduction of the off current, and the subthreshold swing decreased. At a Si mole ratio 0.02, the SZTO TFTs exhibit favorable electrical properties of Vth = 3.0 V, μFE = 1.90 cm2 V-1 s-1, S.S = 0.38 V/decade, and Ion/off = 1.66 × 107. Thus, the SZTO is a promising material for backplanes of displays. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of indium zinc tin oxide (IZTO) thin films grown under different gas environments were investigated by means of x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy (REELS). REELS spectra revealed that IZTO thin films under argon mixed with oxygen had band gaps of 3.07 eV before annealing and 3.46 eV after annealing at 350 °C in air. Meanwhile, the band gap for IZTO thin film grown under oxygen mixed with water and annealed at 350 °C in air was 3.26 eV. Band gaps obtained from REELS spectra are consistent with the optical band gaps obtained using UV-spectrometry. The REELS spectra were quantitatively analyzed based on comparison of the effective cross section for inelastic electron scattering in the REELS experiment to determine the dielectric function and transmittance of the IZTO thin films. It was found that amorphous IZTO films grown under argon mixed with oxygen followed by annealing at 350 °C exhibit higher optical transmittance in the visible-light region, higher carrier mobility, and a high on-off current ratio. [ABSTRACT FROM AUTHOR]

A voltage-controlled ring oscillator is implemented with double-gate complementary transistors where both the n- and p-channel semiconductors are deposited by inkjet printing. Top gates added to transistors in conventional ring oscillator circuits control not only threshold voltages of the constituent transistors but also the oscillation frequencies of the ring oscillators. The oscillation frequency increases or decreases linearly with applied top gate potential. The field-effect transistor materials system that yields such linear behavior has not been previously reported. In this work, we demonstrate details of a material system (gate insulator, p- and n-channel semiconductors) that results in very linear frequency changes with control gate potential. Our use of a double layer top dielectric consisting of a combination of solution processed P(VDF-TrFE) and Al2O3 deposited by atomic layer deposition leads to low operating voltages and near-optimal device characteristics from a circuit standpoint. Such functional blocks will enable the realization of printed voltage-controlled oscillator-based analog-to-digital converters.

In this study, for high-performance indium-free metal oxide channel layer, we synthesize Zn-Sn-O (ZTO) precursor solutions in which formamide is incorporated as an additive for catalyzing the subsequent sol-gel reactions and the evolution of chemical structure. It is revealed that the formamide plays a critical chemical role in evolving a chemical structure with more oxygen-deficient oxide lattice and with less hydroxide, allowing for high field-effect mobility over 7 cm(2)/V·s. Furthermore, it is for the first time demonstrated that electrically active metal-oxide films can be patterned, using an air-brush printing technique, by directly depositing formamide-mediated ZTO-precursor solutions in patterned geometries.

This research presents a sol-gel derived zinc tin oxide thin film transistor (TFT) as a high-stability oxygen sensor. Due to its high sensitivity, oxygen has been traditionally regarded as having a negative influence on the electrical characteristics of zinc-based TFTs; however, TFTs can also act as an oxygen sensor. After illumination with visible light in oxygen-rich ambient, a significant increase in drain current of nearly 104 times occurs with fixed gate and drain voltages. It is expected that an optimized method of illumination can help to reset the electrical characteristics or distinguish the on/off state of this reliable oxygen sensor. [ABSTRACT FROM AUTHOR]