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In this study, ZnO nanotubes, ZnO/ZnS core-shell nanorods, and ZnO/ZnS nanotubes were fabricated. To fabricate different types of ZnO-based nanocomposites, the central area of the ZnO nanorods was etched by a KCl solution and the outward shell was sulfurized to form ZnS/ZnO shell structures. Surface morphologies and material properties of the various nanostructures were examined by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Transmission X-ray Microscopy (TXM). Multiple material characterizations including X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), and Photoluminescence (PL) were performed. Results indicate that larger surface areas and higher defect concentrations can be obtained by the etching of ZnO nanorods. ZnO/ZnS nanotubes formed by sulfurization roughen the shell surface and mitigate defects. Results indicate that ZnO and ZnO/ZnS nanotubes show promise for future sensing device applications.

In this paper, a blue fluorescent organic light-emitting diode (OLED) with a 1 cm2 emitting area was fabricated by a solution process. The ITO/spin MADN:13% UBD-07/TPBi/Al was used as the basic structure in which to add a hole-injection layer PEDOT:PSS and an electron-injection layer LiF, respectively. The device structure was optimized to obtain a longer lifetime. Firstly, the TPBi, which is an electron transport layer and a hole-blocking layer, was added to the structure to increase the electron transport rate. When the TPBi thickness was increased to 20 nm, the luminance was 221 cd/m2, and the efficiency was 0.52 cd/A at a voltage of 8 V. Since the addition of the hole-injection layer (HIL) increased the hole current but did not increase the electron current, the electron transport layer (ETL) Alq3 with the lowest unoccupied molecular orbital (LUMO) was added as stepped ETL to help the TPBi transport more electron current into the emitting layer. When the thickness of the TPBi/Alq3 was 10 nm/15 nm, the luminance reached 862 cd/m2, the efficiency was 1.29 cd/A, and the lifetime increased to 252 min. Subsequently, a hole-injection layer PEDOT:PSS with a thickness of 55 nm was added to make the ITO surface flatter and to reduce the probability of a short circuit caused by the spike effect. At this time, the luminance of 311 cd/m2, the efficiency of 0.64 cd/A, and the lifetime of 121 min were obtained. Following this, the thickness of the emitting layer was doubled to increase the recombination probability of the electrons and the holes. When the thickness of the emitting layer was 90 nm, and the thermal evaporation method was used, the efficiency was 3.23 cd/A at a voltage of 8V, and the lifetime was improved to 482 min. Furthermore, when the thickness of the hole-injection layer PEDOT:PSS was increased to 220 nm, the efficiency increased to 3.86 cd/A, and the lifetime was increased to 529 min. An infrared thermal image camera was employed to detect the temperature variation of the blue OLEDs. After the current was gradually increased, it was found that the heat accumulation of the device became more and more significant. When the driving current reached 50 mA, the device burnt out. It was found that the maximum temperature that the OLED device could withstand was approximately 58.83 degrees C at a current of 36.36 mA.

In this study, ZnO/ZnS nanocomposite-based dual UV light/CO gas sensing devices have been demonstrated for the first time. To characterize the nanocomposites, multiple material characterizations indicated ZnS/ZnO core-shell rods were successfully formed on SiO2 substrates. Moreover, CO gas sensing and UV light detection measurements both revealed that incorporation of a ZnS shell on ZnO nanorods (NRs) can effectively increase gas sensing and light detection capabilities. Owing to their compact size, low cost, and simple fabrication, ZnO/ZnS NR-based gas and light dual-sensing devices show promises in hazardous gas and light monitoring.

ZnO/ZnS nanocomposite-based nanostructures exhibit dual light and gas sensing capabilities. To further boost the light/dual sensing properties, gold nanoparticles (Au NPs) were incorporated into the core-shell structures. Multiple material characterizations revealed that Au NPs were successfully well spread and decorated on ZnO/ZnS nanostructures. Furthermore, our findings show that the addition of Au NPs could enhance both 365 nm UV light sensing and hydrogen gas sensing in terms of light/gas sensitivity and light/gas response time. We postulate that the optimization of gas/light dual sensing capability may result from the induced electric field and inhabitation of electron-hole recombination. Owing to their compact size, simple fabrication, and stable response, ZnO/ZnS/Au NPs-based light/gas dual sensors are promising for future extreme environmental monitoring.

ZnO/ZnS core-shell structures were hydrothermally grown on SiO2 substrates functioning as hydrogen gas sensing chips. Results indicate that a core-shell structure with an appropriate sulfurization period of 10 min had better H2 sensing performance than those of all other growth conditions. Furthermore, multiple material characterizations revealed that ZnS with a growth time of 10 min could form high-quality and good-adherent ZnS powders with moderate thickness attached to the ZnO nanorods. Because of their small size, portability, simple fabrication and high sensitivity, ZnO/ZnS core-shell based H2 gas sensors show promise for future H2 detecting applications.

In this study, zinc oxide nanostructures integrated with reduced graphene oxide (RGO) were fabricated on foldable indium tin oxide substrates. To study the influence of RGO on the material, antibacterial, and piezoelectric properties on the nanostructures, multiple material, antibacterial, and electrical measurements were performed. Results indicate that inserting a RGO layer on the foldable substrate could form nanocylinder ZnO structures, which induced hydrophobicity and better antibacterial properties. Moreover, addition of appropriate RGO into ZnO seed layer may cause the growth of finer ZnO nanorods (NRs) and enhance piezoelectric effects. With stable electrical pulse generative piezoelectric effects and antibacterial properties, ZnO nanostructures with addition of RGO on foldable substrates have potential for future flexible biomedical and electronics applications.

Organic/inorganic hybrid nanostructures-based dual light-detecting/gas-sensing devices were fabricated. In this research, polycrystalline perylene diimide (PDI) membrane was coated on ZnO nanorods (NRs), functioning as sensing nanocomposites. Multiple material analyses including scanning electron microscope (SEM), energy dispersive spectrometer (EDS), high resolution transmission electron microscopy (HR-TEM), X-ray diffractometer (XRD), Raman spectroscopy, and confocal laser scanning microscopy (CLSM) indicate that organic perylene diimide was successfully deposited on ZnO NRs, forming organic/inorganic membrane on the sensing device. To examine the influence of organic/inorganic hybrid nanostructure on photo-sensing and gas-sensing behaviors, UV light detection and CO gas sensing impulse response were measured. Results reveal that organic/inorganic hybrid nanostructure can effectively enhance UV light and CO gas dual-sensing properties with addition of PDI. The coating of organic PDI on the ZnO NRs not only improves the gas interaction capability and gas-sensing stability but also enhances the UV absorption efficiency. Owing to advantages of low cost, simple fabrication, compact size, and device stability, hybrid PDI/ZnO organic/inorganic light/gas dual-sensing devices are promising for future portable hazardous light and gas sensing applications.

Ultraviolet A light (UV-A, 320&ndash, 400 nm), which is unblockable by sunscreen, requires careful detection for disease avoidance. In this study, we propose a novel photosensing device capable of detecting UV-A. Cancer-causing UV light can be simultaneously monitored with tiny rapid response sensors for a high carrier transition speed. In our research, a multifunctional ZnO/ZnS nanomaterial hybrid-sprinkled carbon nanotube (CNT) was created for the purpose of fabricating a multipurpose, semiconductorbased application. For our research, ZnO nanorods (NRs) were grown by using a facile hydrothermal method on SiO2 substrate, then vulcanized to form ZnO/ZnS coreshell nanorods, which were sprinkled with carbon nanotubes (CNTs). Results indicate that SiO2/ZnO/ZnS/CNT structures exhibited a stronger conducting current with and without light than those samples without CNTs. Multiple material characterizations of the nanostructures, including of atomic force microscopy (AFM) surface morphology evaluation, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicate that CNTs could be successfully spread on top of the ZnO/ZnS coreshell structures. Furthermore, chemical binding properties, material crystallinity, and optical properties were examined by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and photoluminescence (PL). Owing to their compact size, simple fabrication, and low cost, ZnO/ZnS coreshell NRs/CNT/SiO2-based nanocomposites are promising for future industrial optoelectronic applications.

Aggregation/disaggregation properties in organic/inorganic interfaces have been intensively investigated recently because modulation of the aggregation effect can enhance the fluorescent emission, facilitate light scattering and strengthen the material strength. In this study, bisindolo quinoxaline-tips (BIQ-TIPs) organic polymers dropped on ZnO nanorods (NRs) to form organic/inorganic hybrid photosensing materials. Multiple morphological and material characterizations reveal that as-deposited BIQ-TIPs polymers self-aggregated on ZnO NR surfaces. UV/VIS measurements and photoluminescence (PL) mapping indicate that the absorption spectra of ZnO NRs can be broadened by incorporating BIQ-TIPs on top of ZnO NRs. Furthermore, light photosensitive measurements indicate that BIQ-TIPs /ZnO NRs-based devices exhibited better UV sensing behaviors than ZnO NR-based devices. Interestingly, BIQ-TIPs /ZnO NRs still possessed moderate green light sensing capability while ZnO NRs and BIQ-TIPs only samples possessed no green light sensing capability. Owing to their compact size, facile fabrication, and versatility, BIQ-TIPs /ZnO NR devices show promise for integration with BIQ-TIPs analogue-based electronic devices and future broadband sensing and light-harvesting applications.

ZnO/ZnS core-shell nanostructures were hydrothermally fabricated on glass substrates. Multiple material characterizations were used to examine the nanostructures. Results indicate that a ZnS shell with a thickness around 10 nm could be viewed on the ZnO/ZnS core-shell structures. Furthermore, different crystalline phases and element compositions in different locations around nearby nanostructures could be found in selected area diffraction patterns and energy dispersive X-ray spectroscopy. ZnS/ZnO nanostructures on glass substrates show promise for future optoelectronic and electronic device applications. Keywords: ZnO/ZnS core-shell, Glass substrate, Nanostructure, Crystalline structure, Composition

Most small molecule organic light emitting diode (SM-OLED) device structures are made in one layer using solution-based processing because the solution is usually a high dissolvent material that easily attacks the layer below it. We demonstrate a simple and reliable stamping technique for fabricating multi-solution process flexible white SM-OLEDs. The structure is anode/spin-hole injection layer/spin-emitting layer/stamping-electron transport layer/cathode. Poly(di-methyl silane) (PDMS) stamp is used for transferring electron transport layer. An intermediate ultraviolet-ozone surface treatment is introduced to temporarily modify the PDMS stamp surface. Then, the solution-based electron transport layer film can therefore be uniformly formed on top of the PDMS surface. After that the electron transport layer film on the PDMS stamp is transfer-printed onto the emitting layer with suitable heating and pressing. A solution-based processing is successfully established to efficiently fabricate flexible white SM-OLEDs. The SM-OLEDs were obtained at the current density of 20 mA/cm 2 , luminance of 1062 cd/m 2 , current efficiency of 5.57 cd/A, and Commission internationale de l'eclairage coordinate of (0.32, 0.35).

Reliability investigations were conducted after GaN-based LEDs were stressed in seawater vapour. Multiple electrical, optical, and material analyses on the fine nanostructures of the LED were examined. Results indicate that dark spots on the surface and etching trenches observed on the cross section might damage the quantum well and degrade LED performance. Dissolved sodium ions might diffuse and punch through the quantum well and be responsible for these spots and trenches.

ZnO/ZnS core-shell nanostructures were successfully synthesized on porous silicon substrates using hydrothermal methods. Multiple morphological and crystalline characterizations were performed on the structures. Results indicate that a uniformly grown ZnS shell with a thickness of around 10 nm could be observed on the cross-section of ZnO/ZnS core-shell structures. Furthermore, different crystalline phases and morphologies could be observed in selected area diffraction patterns between neighboring nanostructures. Material compositional analysis conducted by energy-dispersive X-ray spectroscopy indicate that varied nanostructure element compositions grew perpendicular to the substrate. ZnS/ZnO nanostructures on porous silicon substrates show promise for future optoelectronic and electronic device applications.

In this paper, we adopt solution/evaporation hybrid processes to fabricate white organic light emitting diodes (WOLED) with a light-emitting area of 1.5 cm * 1.5 cm. The hole injection layer (PEDOT:PSS), p-type doped hole transport layer (NPB:F4-TCNQ), and emitting layer (UBH-215:UBD-07:DBP) are coated using the solution process while the electron transport layer (TPBI), LiF, and Al are coated through vacuum thermal evaporation. The light-emitting layer is a fluorescent material (UBH-215 as host) that combines the blue fluorescent material UBD-07 and the red fluorescent material DBP for a dual band light-emitting diodes. We found that if the red DBP doping concentration is too high, the overall emitting color tends toward reddish, and the luminance efficiency decreases. For WOLEDs whose red DBP doping concentration is 0.25%, the luminance reaches 192 cd/m2, and the current efficiency 0.94 cd/A at 9V voltage. Introducing a hole injection layer between the ITO and emitting layer can enhance both the luminance and efficiency of a WOLED. In addition to the hole injection layer, it is found that inserting p-type doped HTL (NPB:F4-TCNQ) between HIL and EML using the spin- coating method can also improve luminance and efficiency. Furthermore, by optimizing and adjusting the dopant ratio and thickness of p-type doped HTL, the luminance reaches 393.1 cd/m2, the current efficiency reaches 1.32 cd/A under 9V voltage, and the OLED lifetime (half-value period) increases from the original 0.8 hours to 2 hours.

In this paper, the flexible white organic light-emitting diodes (WOLED) was fabricated on polyethylene naphthalate (PEN) with structure of ITO/EHI608 (75 nm)/HTG-1 (10 nm)/3% EB502:0.8% EY53 (5 nm)/3% EB502 (35 nm)/Alq3 (10 nm)/LiF (0.8 nm)/Al (150 nm) and was compared with glass substrate the same structure. It was seen that the performances of flexible and glass substrate are almost the same. The luminance, current efficiency, and CIE coordinates of flexible device is 6351 cd/m2, 12.7 cd/A, and (0.31, 0.38) at 50 mA/cm2, respectively. Then, an Al2O3/HfO2 film on polyethylene terephthalate (PET) was deposited using atomic layer deposition (ALD) as a thin film encapsulation layer have been described and compared, such as the characteristics of water permeability and lifetime of flexible WOLED. The results show that the PET/ALD film low value of about 0.04 g/m2d, and the PET film shows WVTR of about 3.8 g/m2/d. The lifetimes of PET/ALD and PET encapsulations are 840 min and 140 min, respectively. Simultaneous deposition of ALD film on PET film gave the lifetime of flexible WOLED is six times longer than device without ALD encapsulation.

Display Omitted Investigating PhOLEDs with different solvents and dopants concentrations.High efficiency white PhOLEDs induced by the electron transport/hole blocking material.To achieve efficient and low-cost small-molecule-based white PhOLEDs. In this study, white phosphorescent organic light-emitting diodes (PhOLEDs) have been demonstrated with small molecule by using solution processes. Spin-coating is employed as the way for deposition method. 4,4'-N,N'-dicarbazole-biphenyl (CBP) which is typical small molecule based ink is used for spin-coating method, and three phosphorescent dopants materials, Firidium(III) bis(4,6-difluoro phenyl)-pyridinato-N,C2'] picolinate (FIrpic), bis1-(phenyl) isoquinoline) iridium(III) acetyl acetonate (Ir(piq)2 (acac))], and iridium(III) tris(2-phenylpy-ridine) (Ir(ppy)3) were prepared. For spin-coating processes, various parameters properties were investigated including materials concentrations, solvents effect, and electron transporting materials to get high efficiency and white color of white PhOLED device. As a result, the precisely controlled solution processes could be a promising technology for solution process can be a good alternative of vacuum deposition technology.

In this research, complex emitting layers (EML) were fabricated using TCTA doping hole-transport material in the front half of a bipolar 26DCzPPy as well as PPT doping electron-transport material in the back half of 26DCzPPy. Blue dopant FIrpic was also mixed inside the complex emitting layer to produce a highly efficient blue phosphorescent organic light emitting diode (OLED). The hole and electron injection and carrier recombination rate were effectively increased. The fabricated complex emitting layers exhibited current efficiency of 42 cd/A and power efficiency of 30 lm/W when the luminance was 1000 cd/m 2 , driving voltage was 4.4 V, and current density was 2.4 mA/cm 2 . A white OLED component was then manufactured by doping red dopant [Os(bpftz) 2 (PPh 2 Me) 2 ] (Os) in proper locations. When the Os dopant was doped in between the complex emitting layers, excitons were effectively confined within, increasing the recombination rate and therefore reducing the color shift. The resulting Commission Internationale de L’Eclairage (CIE) coordinates shifted from 4 to 10 V is (Δ x =−0.04, Δ y =+0.01). The component had a current efficiency of 35.7 cd/A, a power efficiency of 24 lm/W, driving voltage of 4.6 V and a CIE x , y of (0.31,0.35) at a luminance of 1000 cd/m 2 , with a maximum luminance of 15,600 cd/m 2 at 10 V. Attaching an outcoupling enhancement film was applied to increase the luminance efficiency to 30 lm/W.

This study uses a synthetic graphite fiber as the heat dissipation substrate for top-emission organic light emitting diode (TEOLED) to reduce the impact from joule heat. UV glue (YCD91) was spin coated onto the substrate as the insulation layer. The TEOLED structure is (glass; copper; graphite) substrate/YCD91 glue/Al/Au/EHI608/TAPC/Alq3/LiF/Al/Ag. The proposed graphite fiber substrate presents better luminous performance compared with glass and copper substrate devices with luminance of 3055 cd/m2and current efficiency of 6.11 cd/A at 50 mA/cm2. When lighting period of different substrates TEOLED, the substrate case back temperature was observed using different lighting periods. A glass substrate element operating from 5 to 25 seconds at 3000 cd/m2luminance produced a temperature rate of 1.207°C/sec. Under 4000 cd/m2luminance the copper and graphite substrate temperature rates were 0.125°C/sec and 0.088°C/sec. Graphite component lifetime was determined to be 1.875 times higher than the glass components and 1.125 times higher than that of copper.

Hybrid white organic light emitting diodes (HWOLEDs) with fluorescence and phosphorescence hybrid structures are studied in this work. HWOLEDs were fabricated with blue/red emitting layers: fluorescent host material doped with sky blue material, and bipolar phosphorescent host emitting material doped with red dopant material. An electron blocking layer is applied that provides hole red guest emitter hole trapping effects, increases the charge carrier injection quantity into the emitting layers and controls the recombination zone (RZ) that helps balance the device color. Spacer layers were also inserted to expand the RZ, increase efficiency and reduce energy quenching along with roll-off effects. The resulting high efficiency warm white OLED device has the lower highest occupied molecule orbital level red guest material, current efficiency of 15.9 cd/A at current density of 20 mA/cm2, and Commission Internationale de L'Eclairage coordinates of (0.34, 0.39).

A mixed host emitting layer consisting of TCTA and 3TPYMB can greatly increase the efficiency of blue and white organic light emitting diodes (OLED). The hole transport material TCTA can be used as a buffer layer and a hole-transport host emitting layer. Combining TCTA with electron-transport 3TPYMB produces a mixed host emitting layer that can effectively confine the charge carrier within luminous layer. The electron transport layer 3TPYMB reduces electronic injection energy barriers, improves charge balance, and reduces drive voltage to 4.38 V with proper adjustment to optimum thickness. The luminous efficiency of blue light OLED mixed with FIrpic can reach 36.0 cd/A, 27.5 lm/W, and luminous efficiency of white light OLED mixed with Os tangerine adulterant can reach 36.1 cd/A, 26.4 lm/W.

The high haze light-trapping (LT) film offers enhanced scattering of light and is applied to a-Si:H solar cells. UV glue was spin coated on glass, and then the LT pattern was imprinted. Finally, a UV lamp was used to cure the UV glue on the glass. The LT film effectively increased the Haze ratio of glass and decreased the reflectance of a-Si:H solar cells. Therefore, the photon path length was increased to obtain maximum absorption by the absorber layer. High Haze LT film is able to enhance short circuit current density and efficiency of the device, as partial composite film generates broader scattering light, thereby causing shorter wave length light to be absorbed by the P layer so that the short circuit current density decreases. In case of lab-made a-Si:H thin film solar cells with v-shaped LT films, superior optoelectronic performances have been found (V oc = 0.74 V, J sc = 15.62 mA/cm 2 , F.F. = 70%, and η = 8.09%). We observed ~ 35% enhancement of the short-circuit current density and ~ 31% enhancement of the conversion efficiency.

White phosphorescent organic light-emitting diodes (WPHOLED) with high efficiency and low driving voltage were achieved by incorporating an electron transport material (3TPYMB) into a hole transport-type host (TCTA) as a mixed-host structure. For electrons, the emitting layer is nearly barrier-free until they reach the region of exciton formation, which keeps the driving voltage low. Therefore, improved the charge carrier balance within the emitting layer and enhanced the power efficiency of device. White PHOLED at a luminance of 1000 cd/m2 shown a driving voltage of 4.38 V, luminance efficiency of 36.1 cd/A, and power efficiency of 26.4 lm/W was observed. Furthermore, the power efficiency can be improved to 34.27 lm/W, and luminance efficiency to 46.7 cd/A by attaching a brightness enhancement film (BEF).

The effect of the phosphor doping concentration on the optoelectronic characteristics of white phosphorescence organic light emitting diodes (PHOLEDs) was studied. A high efficiency white PHOLED was achieved using the unique efficiency properties of the red-emitting Osmium complex ([fptz = 3-trifluoromethyl-5-(2-pyridyl)-1,2,4-triazole, PPh2Me = phosphineligand]; Os(fptz)2(PPh2Me)2) combined with a well known efficient blue-emitting Iridium complex (bis[(4,6-difluorophenyl)-pyridinate-N,C2′; FIrpic]). The results demonstrate that with 2 wt% Os(fptz)2(PPh2Me)2 co-doped into the blue-emitting layer (10 wt% FIrpic doped into the host), the device can achieve a luminance efficiency of up to 40.4 cd/A (25.6 lm/W) with a good corresponding CIE coordinate (0.39, 0.40). The doping concentrations of the red-emitting and blue-emitting phosphors were adjusted to obtain a pure white light with a CIE coordinate of (0.368, 0.366). A high efficiency white PHOLED was achieved by optimizing the doping concentration of the red-emitting and blue-emitting complexes.

The characteristics of blue phosphorescent organic light-emitting diodes (PHOLEDs) with hole–buffer structure were investigated by inserting a hole transport-type host (TCTA) between the hole transport layer (HTL, TAPC) and emitting layer (EML, FIrpic:26DCzPPy). The hole transport-type host has lower hole mobility than the HTL material, which could effectively control the hole injection current from the HTL into the EML. Moreover, the hole injection barrier from HTL to EML can be reduced due to the suitable HOMO level of the insertion hole buffer layer, which results in the improvement of driving voltage. Furthermore, the power efficiency was improved by controlling the hole injection current through buffer layer thickness optimization. From the experimental results, an optimal blue PHOLED structure was established: ITO/TAPC(20 nm)/TCTA(25 nm)/FIrpic:26DCzPPy(20 nm)/3TPYMB(40 nm)/LiF(0.5 nm)/Al(200 nm). At luminance of 1000 cd/m2, the driving voltage decreased from 6.3 to 5.1 V and power efficiency enhanced from 6.7 to 13.5 lm/W could be observed.

UV-curable organic/inorganic hybrid composites with gas barrier and heat-dissipating capability have been successfully fast synthesized with microwave irradiation and utilized for the encapsulation of top-emitting organic light-emitting diodes (TEOLEDs). Experimental results manifest that lab-made organic/inorganic hybrid composites can effectively not only obstruct the invasion of moisture as well as oxygen in the atmosphere into the device but also lower the temperature of device. Therefore, the lifetimes of TEOLEDs with their encapsulation are 2.2 folds longer than those without encapsulation.

A high heat dissipation material (copper, Cu) was employed as the substrate for top emission organic light-emitting diodes (TEOLEDs). The UV glue was spin-coated onto the Cu substrate as the insulation layer to effectively improve Cu surface roughness and reduce process complexity. From the optoelectronic results, the optimized device with the Cu substrate shows the maximum luminance of 14110 cd/m2 and luminance efficiency of 7.14 cd/A. The surface and junction temperatures are measured to discuss the heat-dissipating effect on device performance. From the results, TEOLED fabricated on a Cu substrate has lower junction (55.34°C) and surface (25.7°C) temperatures, with the lifetime extended seven times. We employed Cu foil as the substrate for flexible TEOLED with maximum luminance of 10310 cd/m2 and luminance efficiency of 7.3 cd/A obtained.

The lifetimes of organic light emitting diodes (OLEDs) have been successfully enhanced with the modulation of LiF thickness and the utilization of encapsulating adhesives, which have been successfully and quickly synthesized with UV irradiation. Experimental results demonstrate that LiF and lab-made encapsulating adhesives can block the invasion of moisture as well as oxygen in the atmosphere into the OLEDs so that the lifetimes of devices with their encapsulation are 18-folds longer than those without encapsulation.

We dissolved hole transport materials α-NPD and NPB in THF solvent, and spin-coated the α-NPD + THF or NPB + THF solution onto ITO anode surface to improve the luminance efficiency and lifetime of flexible fluorescent and phosphorescent organic light emitting diodes. Then the BCP and TPBi were employed as hole blocking layer (HBL) of phosphorescent device and its thickness was optimized. From the experimental results, the maximum luminance efficiency is 4.4 cd/A at 9 V of fluorescent device and 24.4 cd/A of phosphorescent device, respectively. Such an improvement in the device performance was attributed to the smoother surface and good contact between the interface of spin-coated HTL/ITO, the hole were effectively injected from the anode into the organic layer. And the deposited HTL can block excitons from diffusing into the anode to quench, thus improving the luminance efficiency and lifetime greatly.

UV-curable organic/inorganic hybrid nanocomposites have been successfully synthesized with polymer monomers (tetramethoxysilane (TMOS)/3-glycidoxypropyl-trimethoxysilane (GPTMS)) nano-fillers (silica/alumina), curing agents (bisphenol A (BPA)), and photoinitiators (triaryl sulfonium hexafluoroantimonate (TSH)) by in situ polymerization. Their thermal stability, coefficient of thermal expansion (CTE), adhesion strength, and gas barrier capability have also been investigated with thermogravimetry analysis (TGA), thermomechanical analysis (TMA), micro-computer universal testing machine and moisture penetration tests. Experimental results indicate that nano-fillers are completely homogeneously dispersed in the polymer matrices and the increase of nano-fillers in the nanocomposites causes the raise of decomposition temperature (Td) as well as gas resistance and the reduction of CTE as well as adhesion strength. Because lab-made organic/inorganic hybrid nanocomposites have been discovered to exhibit excellent gas barrier properties, we have also applied them for the encapsulation of organic light-emitting diodes (OLEDs) and flexible OLEDs. With lab-made nanocomposite d, the lifetimes of OLEDs and flexible OLEDs can be successfully lengthened to 92 and 36 h, respectively, whereas those of OLEDs and flexible OLEDs without encapsulation are 11 and 7 h, respectively. © 2008 Elsevier B.V. All rights reserved.

We have successfully prepared ultraviolet (UV) curable organic/inorganic hybrid nanocomposites with good thermal stability, moderate adhesion strength, and excellent barrier capability. In order to improve the gas blocking properties, the metal alloy (Invar) has been blended with lab-made organic/inorganic hybrid nanocomposites, dramatically not only raising the gas resistance but also reducing the shrinkage after UV curing. Moreover, we have also applied lab-made nanocomposite IV for the encapsulation of organic solar cells. The experimental results reveal that introduction of nanocomposite IV can effectively block the penetration of moisture as well as oxygen in the air into the devices and consequently promote the lifetime of organic solar cells.

In this work, color/luminance tunable organic light emitting diodes (OLEDs) (ITO glass/naphthyl phenyl benzidine (NPB; 80 nm)/4,4′-bis(diphenylvinylenyl)-biphenyl (ADS082BE; 35 nm)/1,3-bis[2-(2,2′-bipyridine-6-yl)-1,3,4-oxadiazo-5-yl]benzene (Bpy-OXD; 20 nm)/tris-[8-hydroxy-quinoline]aluminum (Alq 3 ; 50 nm)/lithium fluoride (LiF; 3 nm)/aluminum (Al, 80 nm)) with low turn-on voltage (3 V) and high luminance (4850 cd/m 2 at 9 V) have been successfully manufactured. The experimental results reveal that their electroluminescent properties (e.g. hue, luminescent intensity, etc.) can be modulated by the manipulation for the layer thickness of NPB/ADS082BE/Bpy-OXD and the applied voltages. In addition, we have also demonstrated lab-made UV-curable silicone-acrylate encapsulating resin exhibits excellent gas barrier capability so that the half-lifetimes of OLEDs reach 98 h whereas those without encapsulation are only 9 h.

This work demonstrates the use of lithium fluoride (LiF) as a passivation layer and a newly developed UV glue for encapsulation on the LiF passivation layer to enhance the stability of organic light-emitting devices (OLEDs). Devices with double protective layers showed a 25-fold increase in operational lifetime compared to those without any packaging layers. LiF has a low melting point and insulating characteristics and it can be adapted as both a protective layer and pre-encapsulation film. The newly developed UV glue has a fast curing time of only 6 s and can be directly spin-coated onto the surface of the LiF passivation layer. The LiF thin film plus spin-coated UV glue is a simple packaging method that reduces the fabrication costs of OLEDs.

In order to improve the luminance efficiency and flexibility of flexible organic light-emitting diodes (FOLEDs), a buffer layer was inserted between ITO and hole transport layer by spin coating. The buffer layer employed is poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), PEDOT:PSS/Teflon, N,N′-bis-(3-methylphenyl)-N,N′-bis-(phenyl)-benzidine (TPD) or bis[N-(1-naphthyl)-N-phenyl]benzidine (α-NPD). The TPD and α-NPD were first solved in chloroform before spin coating. When 40 nm PEDOT:PSS was employed as buffer layer, the FOLED luminance efficiency increased from 2 to 4 cd/A in comparison with the original device without any buffer layer. If the buffer layer was PEDOT:PSS/Teflon, the luminance efficiency increased slightly to 4.4 cd/A. If α-NPD buffer layer was used, the luminance yield of the FOLED could be increased to levels ⩾5.5 cd/A.

A blue small-molecular organic light-emitting diode (SM-OLEDs) based on a solution-process is investigated in this study. Design of experiment (DOE) with response surface methodology (RSM) was applied to optimize the driving voltage and current efficiency of blue SM-OLED devices. The spin-coating speed of the PEDOT: PSS as hole injection layer and the 26DCzPPy: FIrpic as emitting layer were chosen as two main process input factors. Analysis of variance (ANOVA) was adopted to identify significant factors before regression models were obtained. The optimal material structure was determined by minimizing and maximizing a desirability function relating to selected critical quality characteristics including the driving voltage and current efficiency, respectively.