发光层厚度对双层有机EL器件ITO/PPV/Alq_3/Al发光特性的影响

制备出一组双层有机EL器件ITO／PPV／Alq3／Al，测试并分析了各层厚度不同时器件的光电性能．     

蓝色发光有机电致发光器件

具有多层薄膜结构,发射鲜蓝色光的有机电致发光(EL)器件已经制成并为选择蓝色发光材料制定了二个经验性指南。要获到具有高 EL 效率的 EL 器件,关键是发射层要有优异的成膜能力以及发射极与载流子输运材料的适当组合,避免形成激态复合物。在我们的有机电致发光器件中,有一个器件在电流密度为100mA/cm~2,直流驱动电压为10V 时,蓝光发射亮度达700cd/m~2。     

有机电致发光的效率

描述了评价有机电致发光性能的重要指标－－发光效率问题,从发光机制考虑,一般常用外量子效率和内量子效率来评价。外量子效率是有机电致发光器件输出光子数与注入电子数之比;内量子效率是产生在器件内部的光子数与液入电子数之比,对于光子能否输出到器件外部无关紧要。评价器件性能还有一些其他效率评价方法,如能量效率,功率效率等,特别是外功率效率（1m/W),电流效率（cd/A)也常常用于表征有机电致发光性能,但它们与发光光谱的视觉灵敏度有关,对紫外外辐射器件不适用,另外,利用三重态激子发射可以提高EL器件效率,理论上可达100％,器件结构及材料对器件外量子效率影响至关重要。     

有机LED平板显示器电致发光材料的研究

有机LED平板显示器具有效率高、亮度强、能耗低、色彩丰富以及响应速度快等优点。是近年来发光显示领域的研究热点。作为有机LED平板显示器的物质基础，电致发光（EL）材料是直接影响其器件性能的关键因素。本文在阐述器件结构和发光机理的基础上．重点介绍了有机LED器件的电致发光材料，并对其应用前景进行了展望。     

OLED新领域的发展与突破

OLED（Organic Light Emitting Diode）即有机电致发光。有机电致发光是上世纪五六十年代的产物。1953年，A．Bernanose等人在蒽单芯片的两侧加400V的直流电压时，观察到了发光现象，这是有机EL的最早报道。到了七十年代，单晶方面的工作积累促进了有机电致发光材料的研究。1970年，D．F．Williams等人在100V驱动电压下得到了量子效率达5％的有机EL器件。1987年，美国柯达公司的C．W．Tang及其合作者采用新结构并选用新材料，首次将空穴传输层引入到有机薄膜发光器件中，从而制造了具有双层结构的器件，为有机电致发光的研究开始了一个新的阶段。     

有机/聚合物电致发光器件的稳定性问题

有机/聚合物电致发光(EL)器件走向实用化的最大障碍是其稳定性和寿命。文章综述了有机/聚合物EL器件的稳定性问题,并从器件的失效过程、电极材料及其界面对器件稳定性的影响及有机材料本身的稳定性等方面讨论了器件的稳定性。     

Zn(BTZ)2发光层厚度对白色电致发光器件发光光谱的影响

制备了结构为ITO／TPD／Zn（BTZ）2Al的有机电致发光（EL）器件，经测试发现，Zn（BTZ）2发光层厚度对器件EL光谱有较大影响。当Zn（BTZ）2层厚度分别被控制在50和80nm时，EL谱中都只有1个峰，其峰值分别为580和470nm；当Zn（BTZ）2层厚度被控制在50～80nm时，EL谱同时出现470和580nm的2个峰，且它们的相对发光强度与Zn（BTZ）2层厚度也有关系，随着Zn（BTZ）2层厚度越接近80nm（或50nm）时，EL谱峰值为470nm的光就相对越强（或弱），峰值为580nm的光就相对越弱（或强）。通过调整Zn（BTZ）2层厚度，在65nm左右时得到色度较好的白光器件，其色坐标为（0．33，0．33）。为了研究器件的光致发光（PL）谱，制备结构为TPD／Zn（BTZ）2的有机薄膜，经测试发现，薄膜PL谱与Zn（BTZ）2层厚度无关，其光谱峰值在480nm处，与相关文献报道一致。对上述现象进行了分析。     

有机多层薄膜的电致发光机理

本文介绍了高性能有机电致发光(EL)器件,这些器件是由多层有机薄膜构成的。我们把这些器件分成三类,并从发光层电学性能的角度出发优化了 EL 器件的结构。三种 EL 盒中发射区的位置是由掺杂方法确定的。我们还介绍了与高亮度有机 EL 器件有关的两个重要的发光机理。我们认为,发光层内电荷载流子和分子激子的限制使 EL器件具有高亮度。此外,在双异质结构中,在分子尺寸的区域内,有效地实现了对电荷载流子和分子激子的限制。     

显示技术用稀土有机和稀土无机荧光体研究新进展

主要描述了具有f-f和f-d电子跃迁两类稀土发光材料与它们电子组态相关的发光性能的区别，评述了稀土有机及无机发光材料体系在显示技术中研究的新进展。如在无机体系中，用FED的新型红色CaTiO3:Pr^3 及橙色SnO2:Eu^3 ，用有机体系中新的Eu^3 及Tb^3 配合物分别用于有机EL的红和绿色发光材料，以及含Eu^2 配合物的有机EL特性研究丰富了有机EL技术研究内容。用于白光LED的（Y,Gd)3(Al,Ga)5O12:Ce^3 很引人注目。     

一种新型高压场致发光驱动电路的设计

提出了一种横向高压敏感功率器件的结构，采用SENSE技术制作末端功率器件。该器件是一种新型敏感器件，利用其版图结构及在结终端技术中的特殊结构，可使场致发光(EL)的驱动、智能开关电源等的保护功能更加可靠。在EL控制和驱动电路中，采用一种新型误差放大电路和PWM电路，给出了电路模型参数，并设计了一种具有极低电磁干扰和高稳定度的新型EL电路。     

有机白光LED

有机白光LED主要有电致发光与光致发光两类。电致发光的主要机理有:量子阱发光、激基复合物发光和能量转移。人们对有机电致发光白光LED研究较多,不久将有产品问世;而对光致发光研究较少。与电致发光相比,光致发光造价更小,其荧光量子效率或许比电致发光更高。有机白光LED制备工艺简单、成本低功耗小,具有巨大的应用价值及潜在的市场。对发光显示技术,有机白光LED代表了一条“便宜”经济的路径。综述了有机白光LED的机理及发展现状。     

聚合物电致发光器件的研究进展

聚合物电致发光器件（ＥＬＤ）因其具有许多无机及有机小分子ＥＬＤ所不具备的优点，成为电致发光领域研究的热点。通过掺杂或适当的分子设计可以调谐发光颜色。介绍和评述了聚合物电致发光原理、电致发光器件、电致发光材料的开发及应用前景。     

Effect of exciton diffusion on electroluminescence of organic light-emitting devices

We studied temperature-dependence of electroluminescence (EL) in fluorescent dye-doped and undoped organic light-emitting devices. Results show that the EL efficiency of the fluorescent dye-doped devices increases substantially with rising temperatures, as opposed to the dramatic decrease in EL efficiency of the undoped devices. Our experimental results demonstrate directly that thermally activated exciton diffusion is responsible for the reduced luminescence efficiency of the undoped devices at higher temperatures. However, in the doped devices, EL spectra show that excitons are effectively localized onto the guest molecules, which prevents them from being quenched by randomly distributed nonradiative recombination sites and from exciton–exciton annihilations during thermally activated diffusion, resulting in an enhanced EL efficiency at elevated temperatures.     

Fabrication and Characterization of Organic Single Crystal‐Based Light‐Emitting Devices with Improved Contact Between the Metallic Electrodes and Crystal

Organic single crystals have attracted great attention because of their advantages of high charge‐carrier mobility, high chemical purity, and potential for flexible optoelectronic devices. However, their intrinsic properties of sensitive to organic solvent and fragile result in a difficulty in the fabrication of the organic crystal‐based devices. In this work, a simple and non‐destructive technique of template stripping is employed to fabricate single‐crystal‐based organic light‐emitting devices (OLEDs). Efficient and uniform carrier injection induced by an improved contact between crystals and both top and bottom electrodes is realized, so that a homogeneous and bright electroluminescence (EL) are obtained. Highly polarized EL and even white emission is also observed. Moreover, the crystal‐based OLEDs exhibit good flexibility, and keep stable EL under a small bending radius and after repeated bending. It is expectable that this technique would support broad applications of the organic single crystals in the crystal‐based optoelectronic devices.     

染料掺杂型有机电致发光器件

叙述了采用共蒸发法进行有机小分子掺杂对有机ＥＬ器件效率、寿命和发光色的影响规律。结果表明,小分子掺杂法不但可以大幅度提高有机ＥＬ寿命,还可以获得希望的发光色,同时还提出了掺杂剂的选择标准。     

电致磷光及其有机El的量子效率提高

一般有机电致发光（ＯＥＬ）器件仅利用了单重态发射,因而效率较低,为了提高有机ＥＬ效率,人们设法利用三重态的发射提高其量子效率。本文评述了如何利用三重态发射产生的电致磷光提高有机ＥＬ效率问题。     

Electrical pumped energy up-conversion: A non-linear electroluminescence process mediated by triplet-triplet annihilation

Excitons dominate the optoelectronic properties of organic devices. Normal organic light-emitting devices (OLEDs) generally linearly use exciton to generate electroluminescence (EL), in which one photon is produced from per exciton. Eliminating bi-excitons quenching is of great concern for efficient devices. Here, we have theoretically and experimentally investigated a non-linear EL process mediated by triplet-triplet annihilation (TTA) in rubrene/C₆₀-based OLEDs. This non-linear EL process realizes the electrically pumped up-conversion by promoting two low-energy triplet excitons into one high-energy exciton, thus extremely lowering the working voltage of resulting OLEDs. It is clearly seen that this up-conversion EL intensity essentially exhibits two distinct regimes at different current densities, i.e. a quadratic dependence at low current density where mono-triplet decay is dominant, and a linear dependence at high current density where bi-triplet decay becomes dominant. These results further our understanding of the non-linear optoelectronic process. In particular, our results demonstrate that energetically utilizing the TTA provides possibility of fabricating low-driving voltage, high efficiency OLEDs via non-linear EL process.     

Eu(DBM)_3bath配合物高效EL器件工作机理研究

本文内容主要针对本研究组提出的以 Ｅｕ（ＤＢＭ）３ｂａｔｈ为发射材料的三层结构器件的具体工作原理, 并做了一些能进一步提高效率的尝试,说明了一些具体问题,即混合层模糊界面以及电极结构和空穴传输层材料的 影响．     

Analysis of alternating current driven electroluminescence in organic light emitting diodes: A comparative study

The alternating current (AC) responses of double-injection and double-insulated organic light-emitting diodes (OLEDs) were investigated and compared. To reveal the electroluminescent (EL) processes in these devices, the AC voltage and frequency dependence of the EL intensity and capacitive current were studied in the time domain with a focus on phase difference analysis. It was found that the voltage-dependent transit time and frequency-dependent carrier distribution were important for the AC-driven performance of the double-injection OLEDs. In contrast, although the double-insulated OLEDs shared some similarities with the double-injection OLEDs, they had some unique characteristics, which were the absence of resistive current and phase shift of EL profiles. It was revealed that the EL in the double-insulated OLEDs was driven by the displacement current generated by the ionization of the doped layers, which, however, formed space charge regions and undermined the EL emission. The space charge redistributed the electric field across the devices after the initiation of EL, making the EL maintain for a limited time interval. This effect was significant under low frequency and high AC voltage. Comparing the phase difference between both devices, it was indicated that the space charge effect was responsible for the observed EL phase shift and the asymmetric EL profiles at low frequency and high AC voltage in the double-insulated OLEDs. The proposed model was also of help to understand the EL saturation phenomena with AC frequency and voltage in those devices.     

有机电致发光材料的研究

有机LED平板显示器具有效率高、亮度强、能耗低、色彩丰富以及响应速度快等优点，是近年来发光显示领域的研究热点。作为有机LED平板显示器的物质基础，电致发光(EL)材料是直接影响其器件性能的关键因素。本文在阐述器件结构和发光机理的基础上，重点介绍有机LED器件的电致发光材料，并对其应用前景进行展望。