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With the rapid development of wearable artificial intelligence devices, there is an increasing demand for flexible oxide neuromorphic transistors with the solid electrolytes. To achieve high-performance flexible synaptic transistors, the solid electrolytes should exhibit good mechanical bending characteristics and high ion conductivity. However, the polymer-based electrolytes with good mechanical bending characteristics show poor ion conductivity (10-6-10-7S cm-1), which limits the performance of flexible synaptic transistors. Thus, it is urgent to improve the ion conductivity of the polymer-based electrolytes. In the work, a new strategy of electrospun Li0.33La0.557TiO3nanofibers-enhanced ion transport pathway is proposed to simultaneously improve the mechanical bending and ion conductivity of polyethylene oxide/polyvinylpyrrolidone-based solid electrolytes. The flexible InZnO synaptic transistors with Li0.33La0.557TiO3nanofibers-based solid electrolytes successfully simulated excitatory post-synaptic current, paired-pulse-facilitation, dynamic time filter, nonlinear summation, two-terminal input dynamic integration and logic function. This work is a useful attempt to develop high-performance synaptic transistors.

Fluorescent/phosphorescent hybrid white organic light-emitting diodes (WOLEDs) employing a bipolar CBP interlayer with different thickness have been fabricated. The two-color hybrid WOLEDs at the optimal interlayer thickness exhibit a maximum efficiency of 11.47 cd A−1. Compared with the device without a CBP interlayer, the efficiency of the device is increased by 38.5% and the chromatic stability is also improved. This work found that appropriate thickness of the CBP interlayer with a higher triplet energy level can effectively block the Dexter energy transfer between the phosphorescent and fluorescent layers, which can reduce the energy of triplet in the exciton recombination zone and improve the efficiency of the device. Furthermore, the introduction of the bipolar interlayer with a suitable energy level adjusts the balance of exciton distribution, thereby achieving white light emission with good color stability. The present research could provide valuable strategy in developing hybrid WOLEDs with stable chromaticity.

Solenoid valve is an important part of smart toilet, which plays a very important role in smart toilet products. The influence of comprehensive performance for solenoid valve on the quality of smart toilet is detailed analyzed, the structure of new solenoid valve is designed, comprehensive performance testing system of the solenoid valve is developed, and comprehensive performance for new solenoid valve is tested by using testing system. The test results prove that the new solenoid valve has good comprehensive performance; meanwhile, it also verifies the generality and reliability of comprehensive performance testing system of the solenoid valve.

White organic light emitting diodes (WOLEDs) with copper phthalocyanine (CuPc), 4,4',4''-tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine (m-MTDATA), tungsten oxide (WO3) and molybdenum oxide (MoOx) as buffer layers have been investigated. The MoOx based device shows superior performance with low driving voltage, high power efficiency and much longer lifetime than those with other buffer layers. For the Cell using MoOx as buffer layer and 4,7-diphenyl-1,10-phenanthroline (Bphen) as electron transporting layer (ETL), at the luminance of 1000 cd m−2, the driving voltage is 4.9 V, which is 4.2 V, 2 V and 0.7 V lower than that of the devices using CuPc (Cell-CuPc), m-MTDATA (Cell-m-MTDATA) and WO3 (Cell-WO3) as buffer layers, respectively. Its power efficiency is 7.67 Lm W−1, which is 2.37 times higher than that of Cell-CuPc and a little higher than that of Cell-m-MTDATA. The projected half-life under the initial luminance of 100 cd m−2 is 55 260 h, which is more than 4.6 times longer than that of Cell-m-MTDATA and Cell-CuPc. The superior performance of Cell-MoOx is attributed to its high hole injection ability and the stable interface between MoOx and organic material. The work function of MoOx has been measured by the contact potential difference method. The J–V curves of 'hole-only' devices indicate that a small hole injection barrier between MoOx/N,'-bis(naphthalene-1-y1)-N, N'-bis(phenyl)-benzidine (NPB) leads to a strong hole injection, resulting in a low driving voltage and a high stability.

Experiments of inserting an ultra thin layer of DCJTB at three different levels in a blue emitter layer of a blue device, ITO/CuPc/NPB/TBADN/Alq/LiF/Al, were carried out. The spectra of these devices indicate that the recombination zone is chiefly located near the NPB/TBADN interface, implying that TBADN is capable of electron transport. The inserted DCJTB at TBADN/Alq interface has no contribution to emission, leaving only the blue emission from TBADN, even at high voltage. However, it improved the stability of the device; the half lifetime was prolonged twice more and the rise of applied voltage during ageing was suppressed from 3 V to 0.4 V.

A new white-emitting organic diode was realized simply by inserting a doped hole-blocking layer between the hole-transporting layer (HTL) and the electron-transporting layer (ETL). The structure of this device is ITO/CuPc/NPB/blocking layer:rubrene/Alq/MgAg. Copper phthalocyanine (CuPc) was used as a buffer layer; N,N´-bis-(1-naphthyl)-N,N´-diphenyl-1.1´-biphenyl-4-4´-diamine (NPB) was the HTL; the tris(8-quinolinolato)aluminium complex (Alq) was the ETL; and the trimer of N-arylbenzimidazole (TPBi), 2-(4-biphenylyl-5-(4-tertbutylphenyl)-1,2,3-oxadiazole (PBD) or the 1,2,4-triazole derivative (TAZ) were used as the blocking layers, in which rubrene is doped. The emission spectrum of this device covers a wide range of the visible region and can be sensitively adjusted by the concentration of rubrene. The white emission with CIE (Commission International de l'Eclairage) coordinates x = 0.31, y = 0.32, a maximum luminance of 8635 cd m-2 and maximum luminous efficiency 1.39 lm w-1 (4.9 V) were obtained in the device with a concentration of 1.5% rubrene in TPBi.

We demonstrate a facile method to enhance light extraction in organic light-emitting diodes using a polymer layer with a texture consisting of random upright pyramids. The simple fabrication technique of the textured layer is based on silicon alkali-etching and imprint lithography. With the textured layer applied to the external face of the glass substrate, the organic light-emitting diode achieved a 26% enhancement of current efficiency and a 30% enhancement of power efficiency without spectral distortion over wide viewing angles. A ray-tracing optical simulation reveals that the textured layer can alter the traveling path of light and assist in out-coupling a large portion of light delivered into the substrate. The proposed method is a promising approach for achieving enhanced efficiency organic light-emitting diodes for the simple fabrication process and the effective light extraction.

In this paper, we demonstrated an efficient textured colour conversion layer (CCL) of a down-converted white organic light-emitting diode (WOLED), which was fabricated by a very simple transfer imprinting method based on silicon wafer. The textured CCL not only helped to extract wave-guided light in the device, but also had an outstanding performance in enhancing the colour conversion rate, which was 1.75 times greater than that of flat CCL. Compared to flat CCL, the lower-doped textured CCL produced better white emission and higher efficiency simultaneously. Moreover, the WOLED with textured CCL also exhibited good colour stability at various voltages.

A chromatically stable white phosphorescent organic light-emitting diode using platinum [1,3-difluoro-4,6-di(2-pyridinyl)benzene]chloride (Pt-4) dye as the emitting layer, producing both light blue-monomer and red-excimer emission, is obtained. We have investigated both photoluminescence (PL) and electroluminescence (EL) of Pt-4 dye, which appear to be very different. Whereas the PL spectra reveal monomer and excimer peaks at around 480 nm and 610 nm, the 480 nm monomer and 660 nm excimer emission are characteristic of the EL spectra. It is shown that in contrast to PL, which is ascribed to an energy transfer process, EL emission can be explained by direct hole trapping, which is deduced from the energy levels of Pt-4 dye and 1, 3-bis(9-carbazolyl) benzene host and demonstrated by current density–voltage characteristics of various concentrations.

A chromatic-stable and easily fabricated white organic light-emitting diode with a colour conversion hole injection layer (CC-HIL) has been investigated. The emission layer (EML) was composed of the fluorescent dye p-bis(p − N,N-diphenyl-aminostyryl)benzene doped into the host 2-(t-butyl)-9,10-di(2-naphthyl)anthracene. A red fluorescent polymer poly(2-methoxy-5-[2′-ethylhexyloxy]-p-phenylenevinylene) (MEH-PPV) with hole transport characteristics and relatively high absorbance to blue electroluminescence was used as the CC-HIL. The CIE colour coordinates at (0.33, 0.35) almost remained unchanged under driving current densities from 20 mA cm−2 to 400 mA cm−2 while the current efficiencies reached 3.5 cd A−1 and 4.65 cd A−1 at 20 mA cm−2 and 400 mA cm−2, respectively. The improved performance was attributed mainly to an enhanced out-coupling efficiency and better carrier balance in the EML.

We fabricated different SiNx insulators at a 150–350 °C deposition temperature by plasma-enhanced chemical vapor deposition (PECVD) and investigated the effect of SiNx insulator on the device properties of pentacene-TFTs with a low-cost copper source/drain electrode. A pentacene-TFT with a SiNx insulator at a deposition temperature of 300 °C exhibited the highest saturation mobility of 0.29 cm2 (V s)−1, the lowest threshold voltage of −8.9 V and an on/off current ratio of 5.3 × 106. The best performance of the device with a SiNx insulator at a 300 °C deposition temperature can be attributed to the electrical properties and a relatively large water contact angle of insulator, smooth insulator surface and better crystallinity of the pentacene active layer. The present organic thin-film transistors (OTFTs) with the PECVD SiNx insulator and the low-cost Cu electrode could be a significant step toward the commercialization of OTFT technology.

Pentacene-based organic thin film transistors (OTFTs) with WO3/Au as source/drain (S/D) electrodes were fabricated. In comparison with the pentacene-based OTFT having Au-only S/D electrodes, the performance of a device having WO3/Au S/D electrodes has been considerably improved. The saturation mobility increased from 0.39 to 2.8 cm2 (V s)?1, the threshold voltage reduced from ?21.3 to ?11.2 V, the on/off ratio shifted from 6.7 ? 105 to 1.5 ? 107 and the threshold swing varied from 3.75 to 1.82 V dec?1. The improvement was attributed to (i) the significant reduction of contact resistance by using the WO3 interlayer and (ii) the strong heat radiation during the thermal evaporation of WO3. Our results indicated that using WO3/Au as S/D electrodes is an effective approach to improving pentacene-based OTFT's performance.

p-di(p-N,N-diphenyl-amino-styryl)benzene (DSA-Ph)-based blue top-emitting organic light-emitting devices (TOLEDs) with low bias and single-mode resonant emission were fabricated. Microcavity optimization was demonstrated by altering the hole-transport-layer thickness. C60 was demonstrated to be an effective capping layer and improved the luminance by a factor of 1.6 in between the maximum and minimum transmittance of top contact. For sky-blue TOLED, the luminance was enhanced by 50% by using a dual emission layer composed of DSA-Ph doped 2-(t-butyl)-9,10-di(2-naphthyl)anthracene and DSA-Ph doped tris(8-hydroquinoline) aluminium (Alq3). The improvement was attributed to the energy transfer from Alq3 to DSA-Ph and DSA-Ph directly harvesting carriers in the emission layer of Alq3 : DSA-Ph.

A dual electron-transport layer (d-ETL) with hole-blocking function was successfully applied to a 2-(t-butyl)-9,10-di(2-naphthyl)anthracene (TBADN)-based blue organic light-emitting device (OLED) for improving chromaticity and electron injection. The d-ETL was constructed by sandwiching a 1,3-bis[2-(2,2'-bipyridin-6-yl)-1,3,4-oxadiazol-5-yl]benzene (Bpy-OXD) layer between the emission layer (EML) and the most common ETLs of tris(8-hydroquinoline) aluminum (Alq3) and 4,7-diphyenyl-1,10-phenanthroline (BPhen). Due to the hole-blocking function of Bpy-OXD and thereby the better confinement of carriers within the EML, d-ETL devices showed much better chromaticity and less current-induced color shift as compared to the corresponding single ETL ones. Moreover, the d-ETL devices revealed higher power efficiency (increased by ~30%) and lower driving voltage, indicating an enhanced electron injection. This could be explained by the fact that an interlayer of Bpy-OXD provided a stepped energy level which greatly facilitated electron injection and hence enhanced injection current.

Electron injection and transport in organic devices based on electron transport (ET) materials, such as 4,7- diphyenyl-1,10-phenanthroline (Bathophenanthroline BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Bathocuproine BCP) and bipyridyl oxadiazole compound 1,3-bis [2-(2,2'-bipyridin-6-yl)-1,3,4-oxadiazol-5-yl]benzene (Bpy-OXD), have been reported. The devices are composed of ITO/ET materials (BPhen, BCP Bpy-OXD)/cathodes, where cathodes = Au, Al and Ca. Current–voltage characteristics of each ET material are performed as a function of cathodes. We have found that Ca and Al exhibit quite different J–V characteristics compared with the gold (Au) cathode. The current is more than one order of magnitude higher for the Al cathode and more than three orders of magnitude higher for Ca compared with that of the Au cathode at ~8 V for all ET materials. This is because of the relatively low energy barrier at the organic/metal interface for Ca and Al cathodes. Electron-only devices with the Au cathode show that the electron transfer limitation is located at the organic/cathode interface and the Fowler–Nordheim mechanism is qualitatively consistent with experimental data at high voltages. With Ca and Al cathodes, electron conduction is preponderant and is bulk limited. A power law dependence J ~ Vm with m > 2 is consistent with the model of trap-charge limited conduction. The total electron trap density is estimated to be ~5 × 1018 cm−3. The critical voltage (Vc) is found to be ~45 V and is almost independent of the materials.

We have demonstrated devices based on a p-doped layer consisting of 4,4',4''-tris(3-methylphenylphenylamono) triphenylamine (m-MTDATA) and tetrafluro-tetracyano-quinodimethane (F4-TCNQ) as a hole transport layer (HTL). The typical device structure is ITO/m-MTDATA: x% F4-TCNQ (40 nm)/N, N'-bis-[1-naphthy(-N, N' diphenyl-1,1'-biphenyl-4,4'-diamine)] (NPB) (10 nm)/tris (8-hydroxyquinoline) aluminum (Alq3) (50 nm)/LiF (10 nm)/Al (100 nm). Hole-only devices, where the current only consists of holes, are fabricated to observe the apparent improvement in the conductivity of the p-doped layers. We have observed that such layers lead to a striking improvement of the electrical properties of organic light-emitting devices. In particular, the electroluminescent onset voltage is observed to decrease continuously with increasing doping ratio and is greatly reduced compared to diodes with undoped layers. We have seen that the driving voltage of device 3 (m-MTDATA:4% F4-TCNQ) is reduced ~56% as compared with that of the control device (undoped). This improvement has been attributed to the increased conductivity of the p-doping hole transport layer. It is found that the current efficiency also decreases with increasing doping ratio. This can be attributed to the charge imbalance in the emission layer due to the excess hole injection.

We demonstrated efficient red organic light-emitting diodes based on a host emitting system of 9,10-di(2-naphthyl)anthracene (ADN) co-doped with 4-(dicyano-methylene)-2-t-butyle-6- (1,1,7,7-tetramethyl-julolidyl-9-enyl)-4H-pyran (DCJTB) as a red dopant and 2,3,6,7- tetrahydro-1,1,7,7-tetramethyl-1H,5H,1 1H-10(2-benzothiazolyl)-quinolizine-[9,9a,1gh] coumarin (C545T) as an assistant dopant. The typical device structure was glass substrate/ITO/4,4',4''-tris(N-3-methylphenyl-N-phenylamino) triphenylamine(m-MTDATA)/N,N'-bis-(naphthalene-1-yl)-N,N'-diphenylbenzidine(NPB)/[ADN: DCJTB: C545T/Alq3/LiF/Al]. It was found that C545T dopant did not emit by itself but did assist the energy transfer from the host (ADN) to the red emitting dopant. The red OLEDs realized by this approach not only enhanced the emission color, but also significantly improved the EL efficiency. The EL efficiency reached 3.5 cd A−1 at a current density of 20 mA cm−2, which is enhanced by three times compared with devices where the emissive layer is composed of the DCJTB doped ADN. The saturated red emission was obtained with CIE coordinates (x = 0.618, y = 0.373) at 621 nm, and the device driving voltage is decreased as much as 38%. We attribute these improvements to the assistant dopant (C545T), which leads to the more efficient energy transfer from ADN to DCJTB. These results indicate that the co-doped system is a promising method for obtaining high-efficiency red OLEDs.