GaP/phthalocyanine Langmuir?Blodgett film electroluminescent diode

The electrical and electroluminescent properties of Au/phthalocyanine Langmuir-Blodgett film/GaP diodes are reported. The electroluminescence conversion efficiency is shown to depend on the number of Langmuir-Blodgett layers and is a maximum for a 5.6 nm-thick film. This optimum can be explained in terms of simple tunnel injection theory. A preliminary investigation reveals that the devices are relatively stable and that the maximum power conversion efficiency approaches that of an unencapsulated p-n junction diode.     

An infrared detector utilizing internal photoemission

An infrared detector utilizing internal photoemission as a detection mechanism is demonstrated. The detector consists of a metal-semiconductor contact with photoemission taking place over the associated Schottky barrier. Quantum efficiency and bias effects are investigated.     

Organizations of electroluminescent diode character displays

The author discusses organizations of the essential functional parts of an electroluminescent diode display system, capable of displaying one or more lines of alphanumeric characters. Four different basic organizations are compared from the standpoint of relative cost and operational flexibility.     

A GaP electroluminescent diode matrix display system

A prototype of a single-line alphanumeric character display system has been designed and built using GaP red electroluminescent diodes in a matrix connection for the display elements and low-power TTL integrated-circuit chips for the memory and logic functions. The display is a dot matrix of 7 rows and 72 columns and the associated shift-register memory is such as to allow great operational flexibility which includes the ability to display characters and symbols of variable width and a "rolling" mode of operation, i.e., one column of new display information is introduced periodically at the right end causing the old information to shift one column to the left. Thus, the information travels (rolls) from right to left at reading speed. This type of display system is useful for displaying short transitory messages originating from a remote centralized terminal, e.g., a telephone system in a business environment. The rolling feature allows extended messages to be shown, at reading speed, on a relatively small matrix, and the variable character width makes optimum use of the available display area. The present display serves the purpose of demonstrating feasibility but does not represent an optimum in either technology. A more optimized system using beam-leaded monolithic circuits in both technologies is briefly discussed.     

Optimizing structure for constructing a highly efficient inverted top-emitting organic light-emitting diode with stable electroluminescent spectra

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 reso- nance 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.     

An on-chip temperature sensor by utilizing a MOS tunneling diode

A simple metal-oxide-semiconductor (MOS) tunneling diode was demonstrated for application to an integrated temperature sensor. The MOS diode equipped with a 21-Å oxide was biased inversely at 1.8 V to monitor its substrate temperature through gate current. The gate current increased more than 700 times when the diode was heated from 20 to 110°C. An exponential fitting curve correlated the gate current and the substrate temperature. Moreover, characteristics of the diode were analyzed though C-V and I_{1.8 V}-n_i curves. The good temperature response of the MOS tunneling diode might be useful in self-diagnosis or self-protection IC applications     

有机电致发光显示器件的研究

基于有机电致发光器件的能级结构,阐述电极薄膜优化对提高载流子注入效率的作用。系统评述了红绿蓝三原色有机发光材料在荧光量子效率、稳定性、寿命等方面的进展。在对比分析有机显示器件被动矩阵和主动矩阵两种驱动方式技术特点的基础上,介绍了主动矩阵的薄膜晶体管TFT驱动电路的研究进展及相关技术难点。最后简要回顾有机面板在显示尺寸、色彩及寿命方面的研发成果,并探讨了大尺寸面板在产业化进程中面临的问题及可能的技术解决方案。     

高效绿色磷光有机电致发光器件

使用绿色磷光材料GIr1作为掺杂剂,制备了基于CBP材料的一系列绿色有机电致发光器件(OLED)。其器件的结构为ITO/MoO3(50nm)/NPB(40nm)/TCTA(10nm)/CPB:GIr1(30nm,x%)/BCP(10nm)/Alq3(20nm)/LiF(1nm)/Al(100nm),其中x%为发光层客体掺杂质量分数。对7种不同的掺杂剂质量分数进行了比较,研究了它们的电致发光(EL)特性。结果显示,对发光面积为2.72cm2的器件,GIr1的最佳掺杂比为14%,器件的起亮电压为3.5V,器件的最大电流效率26.2cd/A,其相应的EL主峰位于524nm,色坐标为(0.34,0.61),得到了发光性能稳定的绿色OLED。     

Etching of AC thin film electroluminescent devices

Realization of high definition ac thin film electroluminescent (ACTFEL) devices require fine control of geometric definition. Suitable etching processes need to be defined to address the requirements of both isotropic and anisotropic etching profiles, with good etching rates and high selectivity to underlying Si features. Three different etching processes are analyzed and compared with reference to these parameters. Wet chemical processing provides high etch rates and high selectivities for the ACTFEL materials. Using phosphoric acid leads to an infinite selectivity to all ACTFEL materials. Unfortunately, wet chemical etching has poor control for step profiles. Ion beam etching and sputter etching, however can produce both isotropic and anisotropic patterns, but are comparatively slow and suffer from poor selectivity to the Si based materials. Although individually no method is ideal, for full ZnS:Mn ACTFEL device fabrication these results show that a combination of two of these etching processes will provide the necessary geometry's for very high definition structures     

Analytical circuit model for thin film electroluminescent devices

A simple equivalent circuit is developed for alternating current thin film electroluminescent devices. With sinusoidal excitation voltage an exact analytical solution is presented for calculating the device current, transferred charge and the internal voltage across the phosphor layer. The circuit is used for modeling EL devices with widely varying phosphor layer materials that include ZnS, CaS, SrS, CaF₂, SrF₂, ZnF₂ and multilayer structures prepared with Atomic Layer Deposition. The equivalent circuit gives a straightforward way to characterize the electrical properties of these materials. The fluorides have inferior breakdown properties compared to sulfides although they are much more symmetric. The strong asymmetry of SrS is attributed to its nonuniform defect distribution     

Bright organic electroluminescent devices with double-layer cathode

Electroluminescent devices were fabricated using a diamine derivative and tris (8-quinolinolato) aluminum (III) complex as the hole transport layer and the emitting layer, respectively. The glass substrate/anode/hole transport layer/emitting layer/cathode cells structure was employed. The anode was indium-tin-oxide (ITO) transparent electrode, and the cathode was a double layer consisting of first layer of Mg or Li and the second layer of Ag. Intense bright green emission with luminance of 40400 cd/m² was achieved at 18-V with a current density of 330 mA/cm² for the cell with the Al complex doped with 1 mol.% of coumarin 6 and Li/Ag as the cathode     

p-Doped p-phenylenediamine-substituted fluorenes for organic electroluminescent devices

Two novel p-phenylenediamine-substituted fluorenes have been designed and synthesized. Their applications as hole injection materials in organic electroluminescent devices were investigated. These materials show a high glass transition temperature and a good hole-transporting ability. It has been demonstrated that the 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) doped p-phenylene-diamine-substituted fluorenes, in which F4-TCNQ acts as p-type dopant, are highly conducting with a good hole-transporting property. The organic light emitting devices (OLEDs) utilizing these F4-TCNQ-doped materials as a hole injection layer were fabricated and investigated. The pure Alq₃-based OLED device shows a current efficiency of 5.2 cd/A at the current density of 20 mA/cm² and the operation lifetime is 1500 h with driving voltage increasing only about 0.7 mV/h. The device performance and stability of this hole injection material meet the benchmarks for the commercial requirements for OLED materials.     

高效率绿色磷光有机电致发光器件

采用真空蒸镀的方法,在真空度为5.0×10－4 Pa条件下,分别以传统的材料CBP、TCTA为主体材料,绿色磷光染 色材料(Ir(ppy)₃)为客体材料,制备了相应的有机电致发光 器件,研究发现采用CBP做主体材料的器件比采用TCTA做主体材料的器件能量传递更充 分。之后制备了结构为ITO/NPB(y_1nm)/ CBP:Ir(ppy)₃(x%,y nm)/TPBi(y_2nm)/LiF(0.5nm)/Al 的有机电致发光器件,进一步探究了器件磷光染色材料的掺杂比、器件总厚度对器件性能的 影响。实验结果表明,以CBP为掺杂主体材料,y=20nm,y₂=40nm,x%=8%,当y₁=65nm, 器件亮度达到最高,为67760cd/m²。当y₁=40nm时 ,器件功率效率最高,为41.2lm/W。与此同时,OLED器件的色坐标 均为(0.30,0.61)。     

有机电发光彩色显示屏的新进展

评述了有机电光器件及有机电发光彩色显示屏的最新研究进展。经过多年的研究，有机电发光器件的长寿命这个难题，今天已经达到与经的韧性和亮度相匹配。上前大部分公司的动机是改进封装方案。相信有机ＴＶ挂在墙上的日子将为期不远了。     

Improved property in organic light-emitting diode utilizing two Al/Alq3 layers

We reported on the fabrication of organic light-emitting devices (OLEDs) utilizing the two Al/Alq₃ layers and two electrodes. This novel green device with structure of Al(110 nm)/tris(8-hydroxyquinoline) aluminum (Alq₃)(65 nm)/Al(110 nm)/Alq₃(50 nm)/N,N′-dipheny1-N, N′-bis-(3-methy1phyeny1)-1, 1′-bipheny1-4, 4′-diamine (TPD)(60 nm)/ITO(60 nm)/Glass. TPD were used as holes transporting layer (HTL), and Alq₃ was used as electron transporting layer (ETL), at the same time, Alq₃ was also used as emitting layer (EL), Al and ITO were used as cathode and anode, respectively. The results showed that the device containing the two Al/Alq₃ layers and two electrodes had a higher brightness and electroluminescent efficiency than the device without this layer. At current density of 14 mA/cm², the brightness of the device with the two Al/Alq₃ layers reach 3693 cd/m², which is higher than the 2537 cd/m² of the Al/Alq₃/TPD:Alq₃/ITO/Glass device and the 1504.0 cd/m² of the Al/Alq₃/TPD/ITO/Glass. Turn-on voltage of the device with two Al/Alq₃ layers was 7 V, which is lower than the others.     

Metal-to-metal diode detector utilizing a filamentary crystal

Metal-to-metal point-contact diodes utilizing filamentary crystals were used to detect electromagnetic waves in the shorter wavelength millimeter range. Fabrication techniques were improved as compared with the usually used metal-to-metal diodes utilizing etched tungsten wires.     

White light-emitting organic device with electroluminescent quantum dots and organic molecules

Double-layer organic light-emitting devices are used in combination with quantum dots and blue-light-emitting organic molecules to produce electroluminescence covering the entire visible spectrum. Charges injection is shown to be an important mechanism of excitation in quantum dots. Applications to light-emitting devices with greater spectral flexibility are discussed.     

Frequency response of spontaneous mode electroluminescent diode at low injection levels

The expression for the emitted photon flux of a non coherent electroluminescent diode of flat geometry is determined. Analysis covers both steady-state and transient response; the latter is related to the area and edge emission, respectively, and found to be limited by the diode impedance, by transit time effects in the p and n regions, and by radiation absorption losses. The possibility of an increase of both the external quantum efficiency and modulation cutoff frequency is discussed applying the derived results to the GaAs electroluminescent diode.     

IC storage and access circuitry for an injection electroluminescent diode display

The design of a monolithic IC that is packaged in a hybrid assembly with a linear array of 32 light-emitting diodes to form a basic building block for LED panel display is discussed. The functions of the IC are buffering, inverting, decoding, driving, controlling, LED current regulation, storage, power gating, and lead reduction. Storage is provided by a two- transistor latch that is fabricated in monolithic form using a lateral p-n-p and vertical n-p-n. The random access time between elements in the array is 180 ns for turn-on and 100 ns for turn-off. The IC inputs are compatible with DTL and T/SUP 2/L input levels and the LED output brightness is adequate for viewing in room light.