In this paper, we study device performance and carrier dynamics of an organic light-emitting device (OLED) with an emitting layer (EML) based on a mixed-host (MH) structure. Such a structure is composed of two different host and one dopant materials. It exhibits longer operation lifetime as compared with a conventional heterojunction (HJ) device. In such a MH layer structure, carrier transport characteristic is modified and emission zone position is changed. Energy transfer from the two hosts to one dopant is studied by EL, PL and TRPL measurements. We observe spectrum shift from the EL measurement under different current injection. Incompletely energy transfer from NPB to DPAVBi is shown in cw PL measurement. Time constant at different probe wavelengths with different mixing concentration suggests that different energy transfer in such a MH structure.

We report the technical progress of AMOLED at Samsung SDI, comparing with other technologies. We introduce the voltage-compensational TFT circuit structure to improve the brightness uniformity of AMOLED, which is based on the low temperature poly-silicon. We have developed not only small molecule emitters (phosphorescence and fluorescence) but also polymeric emitters. From red and green phosphors, we achieved longer lifetime and higher efficiency than fluorophors. With the shadow mask patterning and the bottom-emission structure, 20,000-hour lifetime of QCIF device and the power consumption less than 150 mW at 100 cd/m² (30% on condition) were obtained. In the case of the top-emission structure, we could get high efficiency also by maximizing the light out-coupling efficiency and enhance the color purity to the level of the NTSC. We have developed another patterning technology, "LITI: Laser Induced Thermal Imaging" and fabricated 17-inch full color AMOLED, which is the largest AMOLED based on the low temperature poly-Silicon.

In this paper we fabricated a panel consisting of an array of organic TFTs (OTFT) and organic LEDs (OLED) in order to demonstrate the possible application of OTFTs to flexible active matrix OLED (AMOLED). The panel was composed of 64×64 pixels on 4 inch size PET substrate in which each pixel had one OTFT integrated with one green OLED. The panel successfully demonstrated to display some letters and pictures by emitting green light with luminance of 20 cd/m² at 6 V, which was controlled by the gate voltage of OTFT. In addition we also developed fabrication processes for pentacene TFT with PVP gate on PET substrate. The OTFTs produced the maximum mobility of 1.2 cm²/V•sec and on/off current ratio of 2×106.

White polymer light-emitting diodes (WPLEDs) with bilayer structure were fabricated by spin coating method. The device structure used here is ITO/PEDOT:PSS/blend1/blend2/Ba/Al, where blend1 consists of poly(N-vinylcarbazole) (PVK) and copolymer of 9,9-diotylfluorene and 4,7-di(3-hexyl-thien-2-yl)-2,1,3-benzothiadiazole (PFO-DHTBT), and blend2 is the blend of polyhedral oligomeric silsesquioxane-terminated poly(9,9-dioctylfluorene) (PFO-poss) and phenyl-substituted PPV derivative (P-PPV). The copolymer PFO-DHTBT emits red light. The blend2 gives off both green and blue emission bands in electroluminescence (EL) spectrum. the relative intensity of the bands depends on the blend ratios. The EL spectrum of the device can be controlled by respectively adjusting the weight ratios in the blend1 and blend2, thickness as well. At the weight ratios of 100:3 (PVK:PFO-DHTBT) in blend1 and 100:1 (PFO-poss: P-PPV) in blend2, and with keeping the thickness of the two blend films to be 40nm, the white fluorescent light emission with Commission International De L'Eclairage (CIE) coordinates of (0.33, 0.32) is achieved in a large voltage range, the maximal quantum and luminance efficiencies of 3% (ph/eh) and 4.4cd/A are obtained at 6.1V, and the maximal luminance is 6300cd/m² at 10V.

In this paper, a 1.85V reduction in driving voltage of an OLED is presented by using an alkali-metal doped electron transport layer (ETL) and a silver (Ag) cathode. Such an ETL is composed of 2,9-dimethyl-4,7-diphenyl 1,10- phenanthroline (BCP) doped with Cseium (Cs) to increase the conductivity of the organic material and achieve ohmic contact at the ETL/cathode interface regardless the work function of the cathode material. Ag is used to replace the conventional aluminum as the cathode material due to its lower electrical resistivity and optical absorption in visible range. In our devices, the drive voltage was reduced by 1.45V when using MD technique only. When we change the cathode material from Al to Ag, the driving voltage has a further of 0.4V reduction. In those devices, current efficiency is around 3.3 to 4.1 cd/A at 100 mA/cm².That corresponds to an improvement of 53.36% in power efficiency at 10 mA/cm².

Iridium complexes can be used as high efficient light-emitting materials in OLED devices according to its triplet light-emitting properties. In present work, we report two series of iridium complexes with green and red light emitted, respectively. Ir(ppy)₂Ac, Ir(ppy)₂Vb, Ir(btp)₂Ac, and Ir(btp)₂Vb can be used as good phosphorescent light-emitting materials for EL devices. Particularly, these iridium complexes give a possibility to form unique polymer material acting at least as the same as host-guest light-emitting system, which is rather complicated in fabricating process. By the improvement of injecting balance of hole and electron in the device, these iridium complexes can be considered as the potential high efficiency material for OLED use.

In this paper, we conducted photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements for the organic films that was composed of tris(8-hydroxyquinoline) aluminum (Alq₃) as the host and 10-(2-benzothiazolyl)-1, 1, 7, 7-tetramethyl-2, 3, 6, 7-tetrahydro-1H, 5H, 11H, [l] benzo-pyrano [6,7,8-ij] quinolizin-11-one (C545T) as the green dopant with different concentration. Typical quench behavior was observed by typical PL measurements when doping concentration exceeds 2% and the carrier lifetime decreased monotonically with increasing doping concentration in TRPL measurements. Time constant for energy transfer from host to dopant decreased with increasing dopant concentration and saturated above 2% dopant concentration. An anomalous blue shift at the initial probe time-interval was observed when dopant concentration was over 4%. It indicated a fast event energy absorption and/or relaxation process which had a time constant less than two picosecond. Two physical mechanisms with different time constant was observed those accounted for the concentration quench behaviors in the Alq3/C545T system.

Since the initial discovery of electroluminescence in PPV [poly (p-phenylenevinylene)], polymer light emitting devices have been widely investigated. Aiming at overcoming the lack of electron type polymer can be used in polymer electroluminescent devices, using n-type semiconducting inorganic material ZnO:Zn as electron transport layer and p-type semiconducting polymer PDDOPV as hole transport layer, device based on heterojunction with structure ITO/PDDOPV/ZnO:Zn/Al is successfully fabricated. The highest ratio luminescent efficiency of heterojunction device to that of single layer device of PDDOPV is 38.6 times at 8V, the brightness and current of heterojunction device are 19.4 times and 0.5 time of that of single layer device respectively. The results demonstrate that the insertion of ZnO:Zn layer can transport electrons and block holes that lead to the decrease of current and increase of luminescent brightness and efficiency. The electroluminescent spectra of single layer device were bias-independent while that of heterojunction device were bias-dependent. The emitting color of single layer device is orange, while that of heterojunction device shifts from orange to green-yellow and finally becomes green as the applied voltage increases. The full width at half maximum (FWHM) of single layer device is 50 nm, while that of heterojunction device is from 70 to 84 nm. Different photoluminescent spectra of heterojunction device are obtained at different excitation wavelength. Exciplex theory is often used to explain the origin of new emitting color, but it is not suitable here because exciplex emission should leads to red-shift emission. We attribute this phenomenon to the conformation of new light-emitting unit.

A theoretical analysis of the performance of organic light emission diode based flat panel display is presented for three different color reproduction approaches, i.e. color produced by three primary color emitters, color produced by blue emitters coupled with phosphor filters, and color produced by white emitters coupled with transmission color filters. The validity of this simulation is examined with test results from real AMOLED panels made with three primary color emitters.

In this paper, the photoluminescence(PL) from thin films of factris(2-phenylpyridine) iridium (Ir(ppy)₃) doped poly(N-vinylcarbazol) (PVK) modulated by forward bias and reverse bias was measured for the sake of studying the generation and evolution of triplet exciton. The results show that the electric field induced quenching of PL happens before the intersystem crossing from PVK to Ir(PPY)₃. Once the triplet excitons at Ir(PPY)₃ are formed by the energy transfer from PVK to Ir(PPY)₃, it is difficult to dissociate the excitons at Ir(PPY)₃. The triplet excitons locating at Ir(PPY)₃ molecules is very stable. The electroluminescence mechanism of Ir(PPY)₃ doped PVK is also investigated by . For different forward biases, no obvious difference in the profiles of PL spectra is observed, which excludes the influence of electric field and injected carriers on the intersystem crossing from PVK to Ir(PPY)₃. Comparing EL spectra and the electric field modulated PL spectra of Ir(PPY)₃ doped PVK, we can more reasonably deduce that the main EL emission from Ir(PPY)₃ does not come from the energy transfer between PVK chains and Ir(PPY)₃ molecules which obeys Föster rule, but comes from the direct recombination of injected carriers at Ir(PPY)₃ molecules which act as both the carrier-trap and recombination centers.

Recently the growth techniques of single-crystalline ZnO film promote much attention to ZnO-related materials for electronic and optoelectronic applications. ZnO and ZnMgO films were grown by radical-source molecular beam epitaxy, and the epilays on a-plane sapphire substrates had a superior quality in crystallographic, optical and electrical properties. The surface during growth was monitored by a reflection high-energy electron diffraction (RHEED) system. After the growth, these films were characterized by Field emission scanning electronic miroscopy, transmission spectrum, photoluminescence (PL) using 325 nm line of a He-Cd laser, and electrical properties were measured by Hall measurement. The n-type doping with Al was successfully performed up to 5 × 10¹⁹ cm^-3. Widening of bandgap energy by increasing Mg composition was observed by transmission spectrum.

Room-temperature spectral and temporal behaviors of UV and visible emissions in ZnO epilayers grown onto (100) silicon substrates have been investigated by means of time-integrated and time-resolved photoluminescence(TIPL & TRPL). The PL lifetimes as short as 25-50 ps for the excitonic UV lines peaked at ~380 nm were found, indicative of ultrafast trapping of excitons by defects states inside the band gap. Compared to its as-grown precursor, the ZnO epilayer subjected to postgrowth thermal annealing in air showed enhanced intensities of both UV as well green emissions by nearly the same factor of ~3.1, in accompany with complete disappearance of the impurity luminescence peaked at 2.83 eV. More importantly, the green luminescence in the post-annealed ZnO was observed to decay as hyperbolic t^-1 and logarithmically shift its peak emission toward higher energies with increased excitation intensity, in excellent agreement with the tunnel-assisted donor-acceptor pair(DAP) recombination model. The possible mechanism of compensation between intrinsic impurities was also discussed.

Along with the fast development of image technology, its application has nearly reached every field. Image measurement technology has larger measurement speed and its results are prone to observe, contrast, analyze and save. In this study, an image measurement system composed of a CCD camera, a computer and a LED lamp-house, was used to study the characteristic of electron images of machined surfaces obtained under different processing methods. The corresponding relations between the character of different surface textures and of different electron images were established. The character of the machined surfaces' images with different cutting parameters was also studied and the image character parameters' range of standard roughness was established. Meanwhile, image measurement methods of the machined surfaces' quality were studied. Image methods and evaluation indicator in this study have good application performance, which were established by comparing them with traditional measurement methods' results.

Through careful consideration of key factors that impact upon voxel attributes and image quality, a volumetric three-dimensional (3D) display system employing the rotation of a two-dimensional (2D) thin active panel was developed. It was designed as a lower-cost 3D visualization platform for experimentation and demonstration. Light emitting diodes (LEDs) were arranged into a 256x64 dot matrix on a single surface of the panel, which was positioned symmetrically about the axis of rotation. The motor and necessary supporting structures were located below the panel. LEDs individually of 500 ns response time, 1.6 mm×0.8 mm×0.6 mm external dimensions, 0.38 mm×0.43 mm horizontal and vertical spacing were adopted. The system is functional, providing 512×256×64, i.e. over 8 million addressable voxels within a 292 mm×165 mm cylindrical volume at a refresh frequency in excess of 16 Hz. Due to persistence of vision, momentarily addressed voxels will be perceived and fused into a 3D image. Many static or dynamic 3D scenes were displayed, which can be directly viewed from any position with few occlusion zones and dead zones. Important depth cues like binocular disparity and motion parallax are satisfied naturally.

In order to enhance the normal view angle of stereoscopic displays based on parallax illumination, the fundamental way is to restrict the width of the illuminating slit within narrow limits. But the knotty problem is that thin slit will dim the backlight and as a result dropping the brightness of display. A novel architecture to enable base liquid crystal displays to be higher brightness, lower cross talk and auto-stereoscopic mode is described in this paper. A high efficient parallax backlight comprising a recycle barrier block is placed at a distance behind an existing TFT-LCD panel. The barrier provides a series of bright illuminating slits for the parallax image pixels on the display panel and projects the alternate image columns to the observer. The slit is narrow in width so that the display may give diamond-shaped viewing regions with a width of 65mm with slightly cross talk. It can be seen that at the optimum viewing distance from the screen, stereoscopic image can be seen without any glasses. In this paper, the implementation of the backlight component in the auto-stereoscopic TFT-LCD is described in detail and the simulated data are given. The configuration of the prototype and measured performance are presented.

Crystallinic red fluorophores based on donor-acceptor substituted spirofluorene, i.e., PhSPDCV show strong fluorescence in solution (Φ_f ~ 70 %) as well as in solid state (Φ_f > 30 %). Non-doped red OLEDs fabricated with PhSPDCV exhibit authentic red (CIE, x = 0.65, y = 0.35) electroluminescence with brightness over 12,000 cd m^-2 (or > 600 cd m^-2 at 20 mA cm^-2) and remarkable external quantum efficiency as high as 3.6%. On the other hand, the bis-substituted derivatives of spirofluorene BisPhSPDCV show relatively weak fluorescence both in solution (&PHgr;_f < 20 %) and in solid state (Φ_f < 10%). Although saturated red electroluminescence (CIE, x = 0.65, y = 0.34) is also observed, non-doped red OLED containing BisPhSPDCV performs much worse than PhSPDCV OLEDs. Both PhSPDCV and BisPhSPDCV are not amorphous forming loosely packed crystallinic materials in solid state with no intimate π-π interaction.

Since present display technology is projecting 3D to 2D, people's eyes are deceived by the loss of spatial data. So it's a revolution for human vision to develop a real 3D display device. The monitor is based on emissive pad with 64*256 LED array. When rotated at a frequency of 10 Hertz, it shows real 3D images with pixels at their exact positions. The article presents a procedure that the software possesses 3D object and converts to volumetric 3D formatted data for this system. For simulating the phenomenon on PC, it also presents a program remodels the object based on OpenGL. An algorithm for faster processing and optimizing rendering speed is also given. The monitor provides real 3D scenes with free visual angle. It can be expected that the revolution will bring a strike on modern monitors and will lead to a new world for display technology.

Photosynthesis of plants is to absorb the special wavelength of sunlight by the chlorophylls. According to the absorption spectrum of chlorophylls, we managed to make a LED lamp for the growing of green plants, and the relative energy spectrum distribution of the lamp match with the absorbing spectrum of green plants. Because the absorption wavelength range of chlorophylls are respectively 390~420nm, 430~460nm and 650~680nm, we choose different peak wavelength LEDs which are respectively at 400nm, 450nm, 655nm. By calculation, the general energy ratio of the three types of LEDs is 22:46:33, which corresponds to the absorption spectrum of chlorophylls. The illuminance of lamp for the growing of green plants on plants away 0.5 meter is 80lx by measuring. The LEDs lamp can be used to complement light and increase the efficiency of photosynthesis in cloudy, in door or at night. In another word, the photosynthesis is more powerful, and the more carbohydrates are synthesized, supplying enough material and energy for the growing of green plants.

Er³⁺/Yb³⁺co-doped tantalum-phosphate glass was prepared. Compared with the conventional phosphate glasses, the tantalum-phosphate glass posses higher glass transition temperature, and then chemical durability. Based on the measured absorption spectra, the absorption and emission cross sections for ⁴I_13/2 -> ⁴I_15/2 transition and some important radiative properties of Er³⁺ were calculated and discussed by using McCumber theory and Judd-Ofelt theory. The results show the peak values and effective bandwidth of emission cross section are larger and wider. These properties make Er³⁺/Yb³⁺ co-doped tantalum-phosphate glass much more attractive candidates for microchip lasers and integrated optical amplifiers.

The spectral properties of Er³⁺-doped tellurite glasses whose compositions are 40TeO₂-40WO₃-10ZnO-10Na₂O and 40TeO₂-40WO₃-10 PbCl₂-10Na₂O were measured and analyzed by using Judd-Ofelt and McCumber theories. Compared with traditional tellurite glasses, these glasses have more stable thermal properties and the emission spectra and emission cross sections at the 1.53 m band are larger and broader. Based on the measured absorption spectra, the spontaneous transition probabilities, the fluorescence branching ratios and the radiative lifetimes of these glasses were also calculated.

Organic electroluminescent devices have received considerable attention due to their application in flat-panel displays. To achieve full-color displays, it is necessary to obtain organic layers emitting red, green, and blue light, but it is still a challenge to obtain efficient and stable organic layer emitting red light so far. Recently, we found that an organic salt, trans-4-[p-[N-ethyl-N-(hydroxyethyl)amino]styryl]-N-methylphridinium tetraphenylborate (ASPT), exhibits efficient red-light emission. In this paper, we report a multilayer electrolumicescent device incorporating a hole-transport layer, an ASPT layer, and an electron-transport layer. The dependence of the carrier transport and the luminescence on the device structure is investigated in detail. Compared to the monolayer device, the balance between hole and electron injections is significantly improved for the multilayer device, and thus the electroluminescent efficiency and intensity are enhanced.

In this paper, we present the device performance of N⁴,N^4'-Di-naphthalen-2-yl- N⁴, N^4'-di-naphthalen-1-yl-biphenyl-4,4'-diamine (TNB) as the HTL material and bis(10-hydroxyben-zo[h]quinolinato) beryllium (Bebq2) as the ETL material. The mobility of TNB and Bebq2 is at the same order of magnitude from our time of flight (TOF) measurement. Therefore, a device with more balanced carrier transport leads to better device performance. At 10 mA/cm², the drive voltage of the devices is as low as 3.16 V since the use of the high mobility ETL, Bebq2. The voltage variation when changing HTL thickness is nearly the same as that when changing ETL thickness. That shows the voltage drop is higher on HTL than ETL due to the use of high mobility ETL material. That also leads to the more balanced carrier transport than that in a conventional OLED. We also observed that a thinner device has longer operation lifetime that may be due to fewer traps in such a device.

ZnO films on polycrystaline Zn substrates were synthesized by cathodic electrodeposition from an aqueous solution composed only of 0.05M zinc nitrate maintained at 65°C. Their microstructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Photoluminescence (PL) spectra of ZnO thin films prepared at more positive potential (-0.6~-0.8V) show a bond exciton photoluminescence band and intensive broad emission band around 2.17 eV, and three longitudinal optical (LO) phonon replica peaks of the bound exciton around 3.34. When more negative potential (-1.0~-1.4V) was applied in electrodeposition process, ultraviolet (UV) emission bands disappeared. A weak shoulder peak at about 1.87 eV was observed for all samples. The results indicate that more positive electrodeposition potential favors the high quality ZnO film growth. Annealed ZnO films prepared at more positive electrodeposition potentials (-0.6V~-1.0V) exhibit the strong ultraviolet emission at 3.35eV and a negligibly weak deep level emission. Thermal treatment results in the enhancement and sharpening of the excitonic photoluminescence bands and decrease of the deep level emission. Thermal treatment also decreases the Eg of ZnO film prepared at -1.0V from 3.56eV to 3.29eV.

Europium-doped titania nanocrystals were prepared by sol-gel technique and were characterized by X-ray Diffraction (XRD) and Photoluminescence (PL) spectra. XRD results showed pure anatase phase structure of titania, which indicated Eu3+ ions were possibly located in the region near the surface of titania nanocrystals grain. At room temperature, PL spectra were measured; luminescence of the host of titania came from the free excitons, band excitons and defect energy levels respectively under the excitation of 260nm. When these samples were excited under Uv-vis light of 380nm, 395nm, 415nm and 468nm, the spectra showed a series of PL signals which corresponded to characteristic emission of Eu³⁺ions and excitation efficiency was highest at 468nm, while it was hardly 0 at 380nm, that is to say, 468nm was most sensitive excitation line, while in general, it is at 395nm, therefore, the excitation source was extended from ultraviolet to visible light, which was very beneficial to luminescence. These emission peaks corresponded to the transitions of ⁵D₀ -> ⁷F_J (J = 0-4) of Eu³⁺ ions respectively, and pure red luminescence at 616nm arising from the transition of ⁵D₀ -> ⁷F₂ was strongest. The excitation spectra exhibited efficient excitation absorption of the host band gap was quite weak.

The surface of freshly prepared porous silicon exists a large number of Si dangling bonds and defects, which act as non-radiative recombination centers leading to an obvious decay of por-Si luminescence efficiency. We choose HNO₃ to affect the surface of fresh por-Si intending to improve the luminescence property of porous silicon. The experimental results indicate that the photoluminescence intensity of por-Si samples treated by HNO₃ get a four-five times increase and nearly ten days later, the gradually increasing Photoluminescence intensity of these samples become stable. The analysis of XPS and SEM demonstrate that the high oxidization of HNO₃ makes more O atoms absorption on the surface, and non-radiative recombination centers decrease in this way. As a result, photoluminescence intensity enhances, and a good stable luminescence of porous silicon is obtained.

The photoluminescence (PL) spectra at room temperature for monocrystal Si wafer and thermal oxide Si samples doped Nd ion implantation are measured. The results show that all the samples possess blue-violet photoluminescence properties under the ultraviolet light excitation and its light emission is stable. The intensity of PL peaks increases with the increasing of Nd ion dose during ion beam synthesis within a certain limits, moreover, photoluminescence is closely relative to the temperature of thermal annealing. Besides, the feature and appearance of the samples was surveyed with atomic force microscopy (AFM).The photoluminescence mechanism for our samples is also discussed.

The Mg-doped near stoichiometric LiNbO₃ crystal of 30mm in diameter and 20mm in length was grown with top seed solution growth (TSSG) method from Li-rich melt doped with 1mol% MgO. Compared with nondoped congruent LiNbO₃ crystal, fundamental absorption edge of the as-grown crystal shifted to shorter wavelength and position of the OH- infrared absorption peak also changed distinctly. All these results indicated that composition of the as-grown crystal was near-stoichiometric.

Thin films of beta barium borate (β-BBO) have been prepared by liquid phase epitaxy on Sr²⁺-doped α-BBO (001) substrates. The thin films were characterized by X-ray diffraction and X-ray rocking curve. The results of X-ray diffraction indicate that the films show highly (00l) preferred orientation on (001)-oriented substrates. The full width at half-maximum of the rocking curve for the film is as low as 676.6 arcsec, which shows the high crystallinity of the thin film. The absorption edge of β-BBO on Sr²⁺-doped α-BBO substrate is 190 nm. The films show second harmonic generation of 400 nm light upon irradiation with 800 nm Ti: Sapphire femtosecond laser light. These results reveal the possibility of fabricating β-BBO (001) films on (001)-oriented Sr²⁺-doped α-BBO substrates by LPE.

High brightness white light-emitting diode (LED) was fabricated by using the self-produced InGaN single quantum-well (SQW) blue LED chip and YAG:Ce³⁺ phosphor. The luminous intensity of the white LED was up to 2.3cd, the chromaticity coordinate was (0.28,0.34), and the color-rendering index was about 75 at forward current of 20mA and room temperature.

An in-plane switching mode super twisted nematic liquid crystal device with the wide viewing angle characteristics and fast response speed is proposed. Electric filed is applied in the plane of the substrates, unlike a conventional super twisted nematic (STN) mode. The compensation films were used in this mode for obtaining the black/white mode with very small color shift. Compared with the normal in-plane-switching mode and in-plane-switching mode twist nematic configuration, its response speed is improved four times on not only the rise time but the decay time. With the compensation film, the excellent viewing angle, weak color shift can assimilate with that of normal IPS mode. The fast response speed will be useful in designing the video-response liquid crystal displays.

Soluble poly(phenylene vinylene)(PPV)-type polymers have been applied widely as active layers in many optoelectronic devices, such as light-emitting diodes and organic lasers. In such devices their physical thickness are commonly about 100~200 nanometers for the desirable charge transport characteristics and optical interference effects. In this work, poly[(2-methoxy,5-octoxy) 1,4-phenylenevinylene] (MO-PPV) thin films have been prepared from their chloroform solutions of different concentrations. Then their UV-VIS absorption (Abs), photoluminescence (PL) and selective-excitation photoluminescence (SEPL) spectra have been measured at room temperature. A long wavelength emission component near 630 nm has been identified as S2→S0 vibronic band through gaussian decomposition method and confirmed by experiments. The effect of annealing on the optical properties of MO-PPV thin films is also studied. The results show that there exists an optimal treatment temperature under which the maximal excitation intensity can arrive. It can be attributed to the different morphologies in films. In addition, an experimental research about the active polymer photonic well structures of MO-PPV/PMMA pairs has been carried out.

The light-emitting properties based on ladder-type poly (P-Phenylene) (LPPP) with carbon nanotubes were investigated. The light-emitting devices with the heterostructure are consisted of the hole transporter LPPP and the electron transporter Alq₃. Carbon nanotubes of 1 wt % were added in LPPP. The microcavity effect could be achieved by adjusting organic layers between Au and Al electrodes. It was also found that the light emission intensity was further increased and the emission peak was narrowed after doping carbon nanotubes as compared with that of samples without carbon nanotubes. This may be ascribed to increasing conductivity and mobility of organic lagers via doping carbon nanotubes.

In this paper, the field electron emission from carbon nanotubes on oriented growth diamond films was investigated. Carbon nanotubes and orientation growth diamond films were prepared by hot filament and microwave plasma CVD. The samples obtained were characterized by scanning electron microscopy and Raman spectroscopy. The field emission experiments were performed in an ion-pumped vacuum chamber for different samples. The experimental results have shown that the field emission properties of carbon nanotubes films/diamond films structure have greatly been improved. A turn-on field of 0.9 V/μm and a maximum current of 500μA at 1.5/μm were observed. A lower turn-on field of 0.7V/μm was achieved after chemical treatment. This improvement may be attributed to the tiny tip shape of the carbon nanotubes on diamond films, which provided an additional local increase in electric field at the tip end.

In order to solve the problem that feature point imaging quality affects the measurement precision of vision system, a method of optical feature point imaging gray value automation control with movement is proposed. The method eliminates the effect of the relative position changes of camera and feature point on imaging gray value by automatic modulating the current in the feature point and camera exposure time. To control the luminance of feature point automatically, a invariable current source which may be controlled by program is constructed using digitally controlled potentiometer, dynatron, operational amplifier and so on. The experiments prove that the system hold nicer linearity, good sensitivity and response, the control method makes it true that the imaging value of feature point always keeps in the ideal range.

CaO-MgO-B2O3-SiO2 glass co-doped with Eu2+, Dy3+ was prepared, which showed the Long lasting phosphorescence. The luminescent properties of this photoluminescence glass had been studied systematically. The main emission peaking at 476nm was ascribed to the 4f5d→4f transition of Eu2+ in glass matrix. The optical absorption spectra of the samples fabricated under the ambient and reducing atmospheres were measured separately. The sample fabricated in the ambient atmospheres was transparent in wavelength region from 340nm to 1μm. While the samples fabricated in the reducing atmosphere a strong absorption band was observed from 350 to 450nm, and the peak was at the 375nm. This band could be assigned to the absorption of Eu2+ ions. The excitation spectra of the sample fabricated in the reducing atmosphere was measured. A strong peak at 396nm and a weak peak at 439nm were observed. They were ascribed to the transitions of Eu2+ ions. The results were conformed to the conclusion of the absorption spectrum. The afterglow decay process could be divided into two stages. One is an instant attenuation, and the other is a slow. Incorporation of rare ions Eu2+ and Dy3+ into glass matrix could largely change the long afterglow properties of the glass. The analytical results indicated that the co-doped Dy3+ ions acted as hole-trap levels and captured the free holes. It resulted in the property of long lasting phosphorescence of CaO-MgO-B2O3-SiO2 glass co-doped with Eu2+, Dy3+.

Eu²⁺, Nd³⁺ co-doped calcium aluminate (CaAl₂O₄) phosphor with high brightness and long afterglow were fabricated by urea-nitrate solution combustion synthesis at 600°C. The phosphor powder of combustion synthesis were generally more homogeneous and had fewer impurity than phosphor fabricated by conventional solid-state methods, the character could conduce to obtain more exact data. The excitation and emission spectrum indicated that there waxs only one luminescence center Eu²⁺, both of the characteristic spectrums of Eu³⁺ and Nd³⁺ weren't discovered. As a secondary activator, Nd³⁺ could make remarkable influence on the afterglow of phosphor. From altering the moral ratio of Eu²⁺ and Nd³⁺, the lasting time of afterglow and thermoluminescence were studied respectively, when Nd³⁺ wasn't appended, the intensity of initial brightness could compared with other materials which had different ratio of Eu²⁺ and Nd³⁺, however the brightness of afterglow decayed rapidly, the lasting time and brightness of afterglow were improved with reduce the radio of Eu²⁺ and Nd³⁺, while the ratio achieved some value, the lasting time of afterglow become shorten with the reduce of ratio of Eu²⁺ and Nd³⁺. Moreover the depth of trap was calculated from the parameter of thermoluminescence. However, the emission spectrum and XRD patterns didn't change obviously with the altering ratio of Eu²⁺ and Nd³⁺. It showed that the little amount of doped rear earth ions (Eu²⁺ and Nd³⁺) had almost no effect on the CaAl₂O₄ phase composition. Based on these conclusions, the model of the luminescence process of CaAl₂O₄:Eu²⁺, Nd³⁺ was built.

Colloidal CdS stabilized with (NaPO₃)₆ was prepared from Cd(NO₃)₂ and Na₂S. The precursor of poly(p-phenylene vinylene), PPV, was synthesized through Wessling's route. PPV precursor/CdS multilayer films were fabricated via the layer-by-layer electrostatic self-assembly technique. After thermal treating the PPV precursor/CdS films, PPV/CdS nanocomposite films were formed. The colloidal CdS and the composite films were characterized using a UV-vis spectrophotometer and a fluorescence spectrophotometer. A photoluminescence peak of the PPV/CdS multilayer film appears at around 380 nm, suggesting that the photoluminescence of the composite films should attribute to the CdS nanoparticles. The electroluminescence spectra show that a strong luminescence band appears in range 350~650 nm, centering around 530 nm, suggesting that the electroluminescence of the composite films should mainly attribute to PPV. For the ITO/(PPV/CdS)₂₀/Al device, the threshold voltage was about 5 V, and the luminescence intensities increased as the biased voltages increased. In the PPV/CdS nanocomposite film-based light emitting device, CdS plays a role mainly in electron-transporting and PPV works mainly in electroluminescence. However, at higher voltages, CdS nanoparticles may also emit light.

In this paper, we report simulation results of a top-emission organic light-emitting device (TOLED) with a passivation layer composed of silicon dioxide (SiO₂) and silicon nitride (Si₃N₄) to protect organic layers from oxygen and moisture. Usually, the thickness of such a layer is about several micrometers. The electrode material of the device used for simulation is silver (Ag). The anode is thick and opaque while the cathode is thin and semi-transparent. The structure is capped with three pair of SiO₂ and Si₃N₄ as the passivation layer. When SiO₂ thickness is less than 2μm, the output intensity changes and the spectrum peak shifts. The peaks oscillate as a function of the SiO₂ thickness and the period is about 170nm. When the SiO₂ thickness is over 2μm, more than single peak are observed. With a simple model, we found that the frequency difference between two peaks corresponds to the free spectral range of the fabry-perot cavity formed by passivation layer. When a passivation layers is added on the TOLED, the microcavity effect results in the presence of multi-peaks. It limits the view angle and decreases the color purity.

The use of screen-printing technique represents one method for the fabrication of electroluminescent displays. Technology parameters of this technique has a great influence on the performance of thick film electroluminescent structures. We've prepared such structures using this technique and investigated the effects of printed layer thickness an the devices performances. The results demonstrate the impact of phosphor and dielectric thickness on the electrical and optical characteristics of the light emitting structures.

In this paper we developed an optimized process conditions of poly(4-vinylphenol) (PVP) as an organic gate compatible to polyethylene terephthalate(PET) substrate by varying the density of each component of PVP gate and also baking temperature. Pentacene TFTs were fabricated by the above obtained process and the performance was examined to find out the mobility of 0.7±0.2 cm²/V·sec and on/off current ratio of 10₆ and sub-threshold slope of 0.27V/dec, which can be applicable to drive an organic LED. In addition the inverters made on PET substrate provided the gain of 9 and exhibited the minor hysteresis which means the low interface states.

The flexible display and the application of Roll-To-Roll process is difficult because high temperature process of a-Si;H TFT and poly-Si TFT limited the use of plastic substrate. We proposed AMOLED using Pentacene TFT (OTFT) to fabricate flexible display. The first stage for OTFT application to OLED, we analyzed OTFT as driving device of OLED. The process performed on glass and plastic (PET) substrate that is coated ITO and PVP is used for gate insulator. The field effect mobility of the fabricated OTFT is 0.1~0.3cm²/V•sec and Ion/Ioff current ratio is 10³~10⁵. OLED is fabricated with two stories structure of TPD and Alq₃, and we can observe the light at 5V by the naked eye. The wavelength of observed lights is 530nm ~550nm. We can confirm the driving of OLED due to OTFT using Test panel and observe OLED control by gate voltage of OTFT. Also, we verify designed structure and process, and make a demonstration fabricating 64 by 64 backplane based on Test panel.

As we know, Strong fluorescent dyes are important light-emitting materials of OLED. 8-hydroxyl quinoline aluminum (Alq₃) is one of the best electroluminescent materials with good film-formation and thermal, excellent electron-transporting ability. However Alq₃ is mostly employed in OLED device for electron transport layer or host material by vacuum deposition. Because of its poor dissolubility in common organic solvent, and be easily recrystallized from the OLED device, the stability of OLED with Alq₃ is decreased. To overcome such defects, we have designed and synthesized five kinds of Alq₃ derivatives. Their chemical structures were elucidated by IR, 1HNMR and element analysis. Their photoluminescence (PL) and electroluminescence (EL) properties have been investigated and the relationships between molecular structures and light- emitting properties have been studied as well.

A series of blue light-emitting copolymers containing alternative dialkoxy-substituted phenylene group and the fluorene moiety with different functional groups at the C-9 bridge position have been prepared through the Suzuki polymerization in this contribution. The detailed investigation of the optical properties demonstrates that the spectral thermal and optical stability of P1-3 exhibit substantially enhanced resistance to both thermally and optically oxidation by the backbone modification strategy. Moreover, in comparison with P1 and P3, P2 with the spiro-junction shows much higher Tg and significantly improves resistance towards oxidation in the air, indicating that the spiro-junction is a better strategy to prevent the formation of ketonic defects or the migration of the exicitons to these defect sites. These properties have established our desired polymers as a family of promising candidate for optoelectronic applications.

The blue organic light emitting diodes (OLED) based on anthracene derivatives (ADN) doped with distryrylarylene derivatives (BCzVB and DSA-ph) were presented. The device of ADN doped with BCzVb shows high color purity (x=0.146, y=0.162) with maximum luminance 11600 cd/m² (15V), current efficiency 2.8 cd/A, while the device of ADN doped with DSA-ph exhibits a sky blue with as high as efficiency 8.29 cd/A, both have a flat efficiency vs current density responses. A typical blue device of ADN doped with TBPe is used for comparison, which gives greenish blue and a stronger current-induced flyorescence quenching. Three kinds of White organic light emitting devices (WOLED) with different dopants and doping sites were constructed. The cell with a single-doped red dye in the light emitting layer (EML)(single-doped) and the cell with both red and blue dyes doped in a single EML (double-doped as well as the cell with red and blue dyes doped in EML and a green dye in another layer (triple-doped). The triple-doped cell shows much higher performance than other two cells: maximum luminance 21200cd/m², 1026 cd/m² at driving current 20mA/cm², efficiency 6cd/A and a half lifetime over 22245h were reached. A passive display features 102x64 pixels with pixel size of 0.25x0.25mm² pixel pitch 0.08mm, luminance 100 cd/m² at driving duty 1/64, and power consumption of 0.6W was constructed.

A 102X64 monochromatic passive matrix organic light-emitting diode (PMOLED) display was studied for its decay process. The structure of the device was ITO(indium tin oxide )/CuPc (copper phthalocyanine/NPB(N,N'-di(naphthalene-l-yl)-N,N'-diphenyl-benzidine)/Alq₃(tris-(8hydroxyqu-inoline)aluminum):C545(coumarin)/Alq₃/LiF/Al. We carried out a vision inspection and electrical (I-V) and optical characterizations, analyzed the EL (electroluminescence) and PL (photoluminescence) spectra before and after the aging test. The aged device under constant current appeared higher driving voltage, smaller leak current, lower EL and PL intensities which were come from the peeling of cathode/organic layers, the burning of shorted routes between the electrodes and the decomposition of light-emitting materials. The EL intensity remains 75.6% while the PL does 81.4% of their initials values after 17 hours aging, which means the EL and PL decay simultaneously, i.e. the decomposition of emissive material is dominant in the decay process and results in the permanent damage in the display panel.

In this study, high-performance organic light-emitting diodes (OLEDs) with a buffer layer of polytetrafluoroethylene (Teflon) are demonstrated. Compared with copper phthalocyanine (CuPc), a conventional buffer layer, Teflon shows a lower absorption in the wavelength from 200nm to 800nm. OLEDs with a Teflon layer and a CuPc buffer layer were fabricated under the same conditions, and their performances were compared. The results indicate that the OLEDs with a 1.5-nm-thick Teflon buffer layer had a markedly enhanced performance with an efficiency of 9.0cd/A at a current density of 100mA/cm², while those with a 30-nm-thick CuPc buffer layer only showed an efficiency of 6.4cd/A at the same current density.

This paper presents a novel series of dendrimers containing perylene diimide cores, Fréchet-type poly(arylether) dendrons, and peripheral functional units such as hole-transporting groups (carbazole) via a convergent synthetic approach with three generation. The higher generation dendrimer has an obvious site-isolation effect or dilution effect of dendrons, which results in a relatively small red-shift of absorption and emission spectra when they form a solid thin film for applications. The interactions between peripheral units and perylene diimide core in the dendrimers are studied by fluorescence spectra. The steady-state fluorescence shows there is no effective Förster intramolecular energy transfer. DSC results indicate that the incorporation of Fréchet-type poly(arylether) dendrons can improve the amorphous property and increase glass transition temperature (Tg). The preliminary EL results with a single-layer architecture demonstrate that these dendrimers could be utilized as a promising kind of active red luminescent emitters.

Two bisindolylmaleimide derivatives were prepared in good yields, characterized and successfully employed in the fabrication of organic light-emitting-diodes (OLEDs). The absorption spectra and photoluminescence spectra of the compounds in solution and in thin film were also measured and they show larger Stokes shifts (>100nm). With the electroluminescence devices configured as ITO/NPB/dopant:Alq₃ /Alq₃/LiF/Al, they exhibit yellow (A) and orange (B) color. In particularly, the two devices can be turned on at 5.2 V (device A) and 5.9V (device B), and reached the maximum brightness of 15066 and 8593cd/m² at 21V, respectively. From the cyclic voltammetry and the onset absorption, the highest occupied molecule orbital (HOMO) and the lowest unoccupied molecule orbital (LUMO) energy levels can be estimated as A (5.3, 2.9eV) and B (5.4, 3.1eV).

RGB lasers projection displays have the advantages of producing large color triangle, high color saturation and high image resolution. In this report, with more than 4W white light synthesized by red (671nm), green (532nm) and blue (473nm) lasers, a RGB laser projection display system based on diode pumped solid-state lasers is developed and the performance of brilliant and vivid DVD dynamitic pictures on 60 inch screen is demonstrated.