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Indium-gallium-zinc oxide thin film transistor(IGZO-TFT) was fabricated using N2O plasma treated SiNx film as gate insulator and room-temperature deposited IGZO film as active layer.Comparing with the conventional IGZO-TFT,the saturation mobility increased from 4.5 to 8.1 cm2·V-1·s-1,threshold voltage reduced from 11.5 to 3.2 V,threshold swing varied from 1.25 to 0.9 V/dec.The trap states in the N2O plasma treated IGZO-TFT is obviously smaller than that in the conventional IGZO-TFT.Our results indicate that using N2O plasma treated SiNx film as gate insulator is an effective approach for improving IGZO-TFT performance.

Efficient inverted top-emitting organic light-emitting diode(ITOLED) using a thin Cs2CO3 layer modified Al as the reflective bottom cathode is demonstrated.With tris-(8-hydroxy-quinoline) aluminum(Alq3) as emitting layer and MoO3/Ag as semitransparent anode,the Al/Cs2CO3 based ITOLED shows a tune-on voltage of 3.6 V,luminance efficiency of 9.8 cd/A and 3.4 lm/W,which are much better than those(4.2 V,8.6 cd/A,2.85 lm/W) obtained from Mg∶Ag based ITOLED and those(5 V,5.5 cd/A,1.57 lm/W) obtained from bare Al based ITOLED.Electron-only devices research shows that a stronger electron-injection is obtained from Al/Cs2CO3 than Mg∶Ag and Al,which is attributed to the lower work function of Al/Cs2CO3 than Mg∶Ag and Al.The good performance of Al/Cs2CO3 based ITOLED is attributed to the efficient electron injection from the Al/Cs2CO3 cathode as well as a microcavity effect.

The bottom gate thin-film transistors(TFTs) with un-annealed and annealed ZnO film as a channel layer were fabricated.Compared with the un-annealed device,the performance of the device with annealed ZnO had been improved.The saturation mobility increased from 2.3 to 3.12 cm2/(V·s),the threshold voltage reduced from 20.8 to 9.9 V,the threshold swing varied from 2.6 to 1.9 V/dec,and the threshold voltage shifted from 8.0 to 3.4 V after applying a gate bias stress of 25 V for 3 600 s.The experimental results indicate that using annealed ZnO film as channel layer is an effective approach for improving ZnO-based TFT performance and bias stress stability.

Bottom-gate ZnO thin-film transistors(ZnO-TFTs) were fabricated with Ta2O5 film as the insulator.Ta2O5 film was grown by the radio-frequency magnetron sputtering at room temperature.The thickness of the Ta2O5 layers were 100,85,60,40 nm separately.The effect of the thickness on the performance of the ZnO-TFTs was studied.With the thickness of the insulator decreased from 100,85,60 nm to 40 nm,the field effect mobility increased from 50.5,59.3,63.8 to 71.2 cm2/V·s.The surface morphology of the Ta2O5 films were checked by the atomic force microscope,which showed that the root mean square(RMS) of the Ta2O5 films roughness decreases with decreasing the insulator thickness.The Ion/Ioff ratio and the threshold voltage are changed with the insulator thickness.

By doping red dye 4-dicyanomethylene-2-(tert-butyl)-6-methyl-4H-pyran(DCJTB) in the tris-(8-hydroxyquinolinato) metal Mq3(where M=Al, Ga, In) chelate complexes, a series of red-dopant organic light-emitting diodes with different doping concentrations have been fabricated. The electroluminescence efficiency of these red diodes with a DCJTB doped Mq3 emitting layer is found to be decreased markedly with the increasing of doping concentration. Electroluminescence characteristics of these devices are studied in terms of energy levels matching of red-dopant with the host materials and carrier transporting layers.

In order to compare two kinds of blue electroluminescent materials, we have investigated two kinds of blue OLEDs with the similar structrue ITO/CuPc/NPB/JBEM: perylene/Alq/Mg:Ag [device(J)] and ITO/CuPc/NPB/DPVBi: perylene/Alq/Mg:Ag [device (D)]. The difference of luminance and efficiency was not obvious for the two devices. However, there was remarkable difference for their lifetime. The device(J) achieved longer half lifetime of 1035 h at initial luminance of 100 cd/m2, and that of device(D) was only 255 h. According to their energy level diagrams, the difference of their stability may originate from different host materials in the two devices. It may be attributed to the better thermal stability of JBEM molecules than that of DPVBi. It is shown that JBEM may be a promising blue organic electroluminescent material with great stability.

A white organic light emitting diode (OLED) has been constructed by employing a new blue material and a red dye directly doped in the blue emitting layer. For comparison, another white cell with a blocking layer has also been made. The configurations of the devices are ITO/CuPc/NPB/JBEM(P):DCJT/Alq/MgAg (device 1) and ITO/CuPc/NPB/TPBi:DCJT/Alq/MgAg (device 2) where copper phthalocyanine (CuPc) is the buffer layer, N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1.1'bipheny1-4-4'-diamine (NPB) is the hole transporting layer, 9,10-bis(3'5'-diaryl)phenyl anthracene doped with perylene (JBEM(P)) is the new blue emitting material, N,arylbenzimidazoles (TPBi) is the hole blocking layer, tris(8-quinolinolato)aluminium complex (Alq) is the electron transporting layer, and DCJT is a red dye. A stable and current independent white OLED has been obtained in device 1, which has a maximum luminance of 14 850 cd m-2, an efficiency of 2.88 Lm W-1, Commission Internationale de l'Eclairage coordinates of x = 0.32, y = 0.38 between 4-200 mA cm-2, and a half lifetime of 2860 h at the starting luminance of 100 cd m-2. Device 1 has a stability more than 50 times better than that of device 2.

Organic light-emitting diodes (LED) with a microcavity structure and an aluminium-doped zinc oxide ZnO:Al (AZO) anode have been fabricated. Effects of microcavities on the spontaneous emission of the organic LED, such as spectral narrowing, intensity enhancement and angle dependence of the emission, have been observed. Different emission colours have been obtained by changing the thickness of the AZO layer and that of a filler layer. The wavelengths of the cavity modes can be explained on the basis of the calculated total optical thickness of the individual cavities.

Rubrene was doped into the hole transport layer of an organic thin film electroluminescent (OTFEL) device with a double-layered structure. It was found that the dopant has a profound influence on the EL characteristics - it changed the region of light emission, increased the luminescence efficiency by more than 50% and improved the device stability tenfold. The reasons for these effects are discussed based on injection theory and the energy level diagram of the device.

Copper phthalocyanine(CuPc) thin film layer was inserted between the anode indium tin oxide and the hole transport layer TPD of an organic thin film electroluminescent device with a double-layered structure. It is found that the CuPc layer greatly improves the device stability. The durability of the device with CuPc layer increases about 8 times. The fact that at a constant current density the driving voltage remains unchanged with operation time for the device with CuPc layer means that the barriers of the carriers injection are stable due to the inserted CuPc layer.

Some organic thin film electroluminescent (EL) devices with aluminium-doped zinc oxide as the hole-injecting electrode have now been manufactured. Their EL spectra and J - V and B - V characteristics have been studied in detail. The work function and ionization potential of the materials composing the devices have been measured and their energy models given. The EL performance properties have been explained well.

Blue emitting electroluminescent diode using PVCz doped with perylene and BBOT as electron transport has been constructed. The emission spectrum is a mixture of spectra of BBOT and perylene. A luminance of as high as 680 cd/m2 with lumen efficiency more then 0.028 lm/W have been obtained.

A simplified quantitative physical model for electron transport processes in TFEL is proposed. The dissipative current, brightness waveform and charge voltage characteristics of the device can be calculated from this model. Comparison of the computer simulation with the exerimental results shows that this model is nearly satisfactory. Hence some important parameters of these devices can be obtained by computer simulation.

Energy transfer between in N , N ′-bis-(1-naphthyl)- N , N ′-diphenyl-1,1′-biphenyl-4-4′-diamine (NPB) and rubrene was investigated. The device ITO/CuPc/NPB:rubrene/blocking layer /Alq/MgAg, in which copper phthalocyanine (CuPc) is used as buffer layer, NPB as the hole transporting layer (HTL), trimer of N -arylbenzimidazoles (TPBi) [or 2–(4–biphenylyl)–5–(4–tertbutylphenyl)–1,2,3–oxadiazole(PBD) or 1,2,4–triazolederivative(TAZ)] as the blocking layer, Tris(8-quinolinolato)aluminum complex (Alq) as electron transporting layers (ETL), can not give white emitting light. White emitting light can be realized in a new device with the structure ITO/CuPc/NPB/blocking layer:rubrene/Alq/MgAg, in which rubrene is doped in blocking layer instead of in NPB. The emission spectrum of this device covers a wide range of visible region and can be adjusted by the concentration of rubrene. The white emitting devices with CIE coordinates x =0.31, y =0.32, maximum luminance 8635 cd/m 2 and luminous efficiency 1.39 Lm/w, were obtained with the blocking layer TPBi doped with 1.5% rubrene.

Organic thin film transistors (OTFTs) with modified gate insulator were demonstrated in this paper. The modified gate insulator layers consisted of SiO2 as the gate insulator and OTS ( octadecyltrichlorosilane ) or PMMA (Poly(methyl methacylate)) as the modified layer. The devices with the modified layer had field-effect mobility larger than 10-3 cm2/Vs, which was twice than that of the OTFT without modification. The on/off current ratio was increased one order of magnitude and reached more than 104. The leakage current was decreased from 10-9 A to 10-10 A. The results demonstrate that using modified gate insulators can obviously improve the performance of the OTFTs.

Tin sulfide (SnS) solar cell semiconductor thin films were prepared by an RF sputtering method. The component, crystal structure, optical properties and electrical properties of SnS films were measured. The relationship between the SnS films properties and the sputtering condition was discussed. Using Sb as a dopant and combining thermal annealing at elevated temperatures (about 400/spl deg/C), n-type SnS homojunction solar cell thin films were obtained.

We demonstrate a highly efficient inverted top-emitting organic light-emitting diode (TOLED) having stable electroluminescent spectra and color coordination with variation of viewing angles by simply tuning the resonance wavelength corresponding to the free emission of the emitter. Using a doped fluorescent emitting system, the inverted TOLED exhibits an enhanced maximum current efficiency of 19 cd/A and a power efficiency of 17 lm/W, which are much higher than those (11 cd/A and 5 lm/W) of the counterpart with normal structure, although both TOLEDs behave with similar stable electroluminescent spectra characteristics. The results indicate that we provide a simple and effective method of constructing an excellent inverted TOLED for potentially practical applications.

RGB pixel generation by microcavity top-emitting organic light-emitting diodes (TOLEDs) is beneficial to both the reduction of the light loss and the improving the color purity and efficiency. Based on the multi-emitting layers, white organic light-emitting diodes (OLEDs) and microcavity TOLEDs were prepared. TOLEDs were made using Ag/ITO as the reflector and adjusting layer, Al/Ag as the semi-transparent cathode, and Alq：DCJTB/TBADN：TBPe/Alq：C545 as white light emitting layer. By adjusting the thickness of ITO, optical length of cavity the colour of the device can be changed, so the RGB tricolor devices are obtained. The peak wavelengths are 476，539 and 601nm, the commission Internationale d'Eclairage (CIE) coordinates are (0.133，0.201)，(0.335，0.567) and (0.513，0.360), and the FWHM are 32，50 and 73nm for Blue, Green and Red，respectively.

Devices using red phosphorescent dye as dopant with exciton blocking layer were constructed. The device structure is ITO/CuPc/NPB/TPBi:Btp2Ir(acac)/TPBi/Alq/LiF/Al. The EL spectra, luminance-current, efficiency-current characteristics of the device have been investigated. At the CIE coordinates x=0.62，y=0.35，efficiency 2.43cd /A has been achieved. At 20mA/cm2 and 400mA/cm2, luminance is 431cd/m2 and 4798 cd/m2, respectively. The effects of the emitting layer thickness on efficiency and EL spectra of the device have been studied also. With the decrease of the emitting layer thickness, efficiency decreases and the blue band of the El spectra increases. For the thickness d2Ir(acac) HOMO energy level. For the thickness d>20nm, the decrease of the efficiency is attributed to the added invalid emitting-layer and more annihilation centers.