A novel structure of illumination system based on laser sources and gradient-index (GRIN) lens arrays for single-plate digital light processing (DLP) projector is proposed. Under the evaluation of light collection efficiency and illumination uniformity, we designed two different architectures of GRIN lens arrays: the unit lens cross section being either square or circular. Also, we designed the one-to-one coupling mechanism between GRIN lens array and Gaussian beam array. By means of three-dimensional modeling and ray tracing, we simulated the optical characteristics of illumination system, and the optical parameters are evaluated. Results show that the total light collection efficiency is 37.9%, the illumination uniformity is 89.7% and the volume is only 12.4 cm3. Thus we improved optical characteristics and reduced the physical dimension of DLP optical engine.
A 1.8-in. high-resolution passive matrix OLED (PMOLED) display panel has been successfully developed. We design the structure of full color PMOLED device. We pattern the device on a 128×3×160 pixel area, 384 row ITO anodes and 160 column cathode separators on ITO glass developed by us through photolithograph process. We have successfully fabricated the 1.8-in. 128×160 full color passive OLED display panel through our SUNICEL PLUS 200 OLED systems. The structure of OLED is a double-hetero structure. It has the device structure of ITO/2TNATA/NPB/ Alq3+C545T/Alq3/LiF/Al for green, ITO/2TNATA/ NPB/Alq3+Rubrene+DCJTB/ Alq3/LiF/Al for red, ITO/2TNATA/
NPB/EB43+TBPE/Alq3/LiF/Al for blue. The PMOLED display panel has full color emission with a resolution of 128×160, and the brightness of 200 cd/m2, as well as the lifetime of 5000 hours. The open aperture ratio of each pixel is 45%.
White OLEDs (WOLEDs) have attracted much attention for several applications, such as backlights in LCD, full-color
OLED display using on-chip color filters, and low cost illumination sources. OLEDs have typically very broad emissions,
which makes them uniquely suitable for light source applications. In this paper, some fundamentals of the CIE
colorimetry system including the color-rendering index are described. Given the spectral power distribution of WOLED,
the parameters of a light source (chromaticity coordinate, CCT, CRI, and the luminous efficacy) can be calculated. A
MATLAB program for this purpose is developed in this paper.
WOLEDs utilizing two primary-color emitters are fabricated. NPB doped with 2% Rubrene is used as the red-emitting
layer and anthracene derivative as the blue-emitting layer. With a structure of ITO/2TNATA(20nm)/NPB(20 nm)/
NPB:rubrene(2%)(10nm)/ anthracene (30 nm)/Alq3(20nm)LiF(1nm)/Al(100nm), a white light with CIE coordinates of
(0.34, 0.37) is generated. The color properties are presented in this paper. The results show that the white color can be
created from numerous combinations of different spectra. Based upon this, the characterization of the WOLED is
simulated and the design of WOLED for illumination is discussed.
In contrary to light source applications where illumination quality white is the most important, all colors are equally
important for display applications. The white spectrum of the two-emitter WOLED is transmitted through the typical red,
blue and green color filters. The performance of this color display is simulated and the WOLED design for display
application is discussed.
Organic light emitting diodes (OLEDs) have attracted much attention for several applications, such as light source and display. It is of both commercial and scientific interests to improve external quantum efficiency of such light emitters. The external quantum efficiency of OLED is determined by the combination of charge balance, singlet-triplet ratio and light extraction efficiency. Application of phosphorescent emitting materials can produce internal quantum efficiency very close to theoretical limitation. However, due to the refractive index mismatch between air and organic emitting layer, most of the emitted light is lost through total internal reflection into substrate and indium-tin-oxide (ITO) waveguiding modes and to self-absorption. Therefore, there is a large space for improvement on the extraction efficiency of the devices. In this paper, A Monte Carlo simulation of external emitted light has been developed. The light extraction factor for planar OLED is 17.17%. This result demonstrates that the light extraction from planar OLEDs can be quantitatively modeled by a simple ray-tracing algorithm. Microlens arrays are introduced on glass substrates to suppress waveguiding loss in the substrate. In this work, we propose to use an etched glass master for fabricating microlens. The glass master is fabricated using a simple wet etching method. A photoresist/Cr/ITO multiplayer mask is made by lithography on the glass substrate and then the glass substrate is etched with HF/HCl solution for improving the quality of generated surface. The isotropic etching profile of the glass master is utilized for microlens replication. Lens arrays are replicated on polymer (PDMS) substrates. With the use of microlens arrays, the light extraction factor is increased experimentally, without detrimental effect to the electrical performance of the OLED.
In this study, four kinds of organic light-emitting diodes were developed using vacuum deposition technique. The typical multilayer structures of OLED are ITO / CuPc(200 Å) / α-NPD(600 Å) / Alq3(400 Å) : C545T(X%) / Alq3(200 Å) /LiF(10 Å) / Al(1000 Å) , X% is the doping consistence in Emitter Layer of OLED. The value is change from 1% to 4%. In this letter, the optical and electronic performance including brightness, efficiency, spectrum etc. was change with the doping consistence. When X% is 1%, the steady voltage of device start working is lower than other structures, only 2.5V. When X% is 3%, the brightness of the device was measured to be 10,500cd times m-2 at the drive voltage 20V, CIE coordinates x=0.331, y=0.625 and maximum luminous efficiency 6.72 lm•W-1 at 5 V. When X% is 4%, the green emission spectrum peak is 550nm, almost reach 555nm (standard green spectrum peak).
A full color 2.2" passive matrix organic light-emitting diodes (OLEDs) with 128 (RGB) * 160 pixels was developed. The display features that driving circuit can transform 18 bits gray-scale data from a PC to the OLED panel via a DVI channel. The size of the pixel was 240μm×240μm, while that of mono sub-pixel is 190μm×45μm. The lifetime of panel was estimated over 5000h because of the use of dual-scan driving technology, and the power consumption of the display was 300mw about when the average luminance of panel reach 40cd/m2.
A novel 5-in. R.G.B densely packed poly-crystal MgAl2O4 (magnesium-aluminum-oxide) phosphor screens with multi-layer interface filter have been developed. The filter is a multi-layer alternate high and low index of refraction film which was fabricated by depositing high index of refraction of titanium oxide and low index of refraction of silicon oxide. The 5-in.R.G. B densely packed poly-crystal phosphor screens with the filter have 60% more luminance than those of common R.G. B poly-crystal phosphor screens, and the area of their chromaticity is almost 10% larger than that of common poly-crystal phosphor screen. The 5-in.R.G. B densely packed poly-crystal phosphor screens with multi-layer interface filter are fabricated by using a centrifugal sedimentation method. The resolution of densely packed poly-crystal phosphor screen with multi-layer interface filter is higher than that of conventional poly-crystal phosphor screen. An experimental 52-inch TV set adopting the set of 5-inch densely packed poly-crystal projection CRT with multi-layer interface filter has very high resolution of 2000 TV lines and 1800 cd/m2 luminance, and it is easy to realize the HDTV display.
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.
The crosstalk, equivalent circuit, voltage drop and power consumption of passive matrix organic light-emitting diodes (PMOLEDs) are quantitatively analyzed, and a mathematical model to calculate the power of PMOLEDs is built. In particular, the advantages of dual-panel PMOLEDs are discussed. The model demonstrates that the power of dual-panel PMOLEDs can be significantly reduced comparing with that of single-panel PMOLEDs. Two 2.5-in. 128×64-pixel green small molecule PMOLEDs have been fabricated. One is single-panel, and the other dual-panel. The power consumption of dual-panel PMOLEDs is 25% less than that of single-panel when both are operated at an average luminance of 100cd/m2.
A novel transparent organic light emitting diode (TOLED) has been developed. This TOLED features Lanthanum hexaborides (LaB6) as transparent cathode and has the device structures of ITO/TPD/Alq3/LaB6. LaB6 film was prepared by the electrons evaporation. This device has the transparency of ~70% in visible spectra, and reach a luminance of 100cd/m2 at 7.2v corresponding to injected current density of 4.8mA/cm2.
We have ever reported a phosphor screen, which is a 5-in. poly-crystal MgAl2O4 phosphor screen. The 5-in. poly-crystal MgAl2O4 phosphor screen has a very good performance, such as high luminance, high resolution, cheap cost and easily obtained. Recently we develop a high performance 5-in. poly-crystal phosphor screen. We deposit a multi-layer interface filter on the poly-crystal MgAl2O4 substrate. The filter is a multi-layer alternate high and low index of refraction film which was fabricated by depositing high index of refraction of titanium oxide and low index of refraction of silicon oxide. The measurement results show that the filter not only increases the MgAl2O4 phosphor screen’s white-D luminance, but also improves its chromaticity. The 5-in.R.G. B poly-crystal phosphor screens with the filter have 60% more luminance than those of common R.G. B poly-crystal phosphor screens, and the area of their chromaticity is almost 10% larger than that of common poly-crystal phosphor screen. The 5-in.R.G. B poly-crystal phosphor screens with the filter realize the authentic high performance.
Conventionally, small-molecule organic electroluminescent device is fabricated by vacuum depositing technology. In this paper, a novel small-molecule organic electroluminescent device was proposed. We adopt spin-coating technology to fabricate the device. It makes the fabrication of small-molecule organic electroluminescent device very simple and low-cost. The device has a brightness of 100 cd/m2 at the 16V DC drive voltage.
We have developed a 5-in. poly-crystal phosphor screens for projection CRTs using poly-crystal materials as the phosphor screen substrate. The poly-crystal materials has the same excellent physicochemical characteristics as the YAG has such as high thermal conductivity and high intensity as well as high optical transparency, but also the bigger diameter of the poly-crystal faceplate can be easily obtained and the cost of the poly-crystal faceplate is only a tenth of that of the same diameter of YAG. Furthermore, poly-crystal substrate is obtained by stamping technological process. The poly-crystal phosphor screens may be satisfied to the needs of large-scale production. An experimental 48-in. rear-projection TV incorporating the projection tubes achieved more than 1600 TV lines of horizontal resolution and 1800 lumens of brightness.
A 3-inch phosphor screen using YAG single crystal as the substrate has been developed for compact projection displays. In order to obtain higher brightness, high resolution and high resistivity against high-density electron bombardment, the phosphor screen properties are improved from the bulk property of the phosphor as well as the screen process. An improved phosphor which has an optimum phosphor composition of (formula available in paper) has been developed.
It is found that the deterioration of the projection phosphor screen is accelerated by phosphor screen heating. Therefore, a critical step in the development of projection tubes of greater luminosity is the improvement of the phosphor deposition method that relies in a higher thermal conductivity of the phosphor layer. We have developed a novel phosphor deposition technique for YAG projection display application.