掺杂聚合物薄膜黄绿发光二极管

在具有电致发光的有机聚合物薄膜ｐｏｌｙ(２－ｍｅｔｈｙｏｘｙ－５－ｅｔｈｙｌｏｘｙ)－４－ｄｉ－(２－ｍｅｔｈｙｏｘｙ－５－ｏｃｔａｏｘｙ)－ｐｈｅｎｙｌｏｎｅ－ｖｉｎｙｌｅｎｅ(简称 ＭＥＭＯ－ＰＰＶ)中掺入一种高荧光量子效率的染料罗丹明６Ｇ(Ｒ６Ｇ),用旋转涂敷的方法获得了发光层,同时将其作为空穴传输层,以８－羟基＠$铝(８－Ａｌｑ３)作为电子传输层,得到了多层有机发光二极管ＩＴＯ/ＰＰＶ:Ｒ６Ｇ/Ａｌｑ３/Ａｌ．该器件峰值波长为５５０ｎｍ,发黄绿光．研究结果表明:不同掺杂浓度对器件发光光谱产生较大影响;通过掺杂,可显著提高器件的稳定性．在１８Ｖ下,器件的亮度达到３６００ｃｄ/ｍ２,外量子效率达３．２%．     

利用PtOEP掺杂改善Spiro发光器件的发光效率

为了利用有机三线态发光提高有机发光器件的发光效率,用磷光材料掺杂到聚合物主体中作为发光层,制备有机电致发光器件.在测量器件的电流-电压特性、发光亮度-电压特性和电致发光谱的基础上,计算了器件的外量子效率,研究了磷光材料的掺杂浓度对器件发光效率的影响.结果表明,对特定的材料体系,适当控制掺杂浓度,可以同时观察到荧光和磷光光谱,使掺杂器件的外量子效率在纯聚合物发光器件的基础上得到明显提高.     

利用PtOEP掺杂改善Spiro发光器件的发光效率

为了利用有机三线态发光提高有机发光器件的发光效率,用磷光材料掺杂到聚合物主体中作为发光层,制备有机电致发光器件.在测量器件的电流-电压特性、发光亮度-电压特性和电致发光谱的基础上,计算了器件的外量子效率,研究了磷光材料的掺杂浓度对器件发光效率的影响.结果表明,对特定的材料体系,适当控制掺杂浓度,可以同时观察到荧光和磷光光谱,使掺杂器件的外量子效率在纯聚合物发光器件的基础上得到明显提高.     

Tracepro在OLED微透镜设计中的应用

有机电致发光从最初进行的研究直到今天,在许多方面都有了很大的突破,但目前仍存在着一些困难,例如器件的寿命就是比较关键的问题。如果器件具有较高的发光效率,便可在出射光子数相同的情况下,减少电子数的注入,从而降低了器件的焦耳热,提高了器件的寿命,所以提高OLED的量子效率是解决器件寿命问题的关键所在。利用微透镜提高器件的外量子效率可以取得明显的效果。本文探讨了Tracepro在OLED微透镜设计中的应用。     

Tracepro在OLED器件模拟中的应用

有机电致发光从最初进行的研究直到今天,在许多方面都有了很大的突破,但目前仍存在着一些困难,例如器件的寿命就是比较关键的问题。如果器件具有较高的发光效率,便可在出射光子数相同的情况下,减少电子数的注入,从而降低器件的焦耳热,提高器件的寿命,所以研究OLED的光线传输机制来提高OLED的量子效率是解决器件寿命问题的热点所在。本文利用Tracepro对OLED器件进行光学仿真,并与理论值进行比较。     

稀土配合物有机电致发光

稀土元素具有独特的电子层结构，是一类丰富的发光材料宝库。将稀土配合物应用于有机电致发光显示器件（OLED）对于实现全彩色显示具有重要意义。与通常的有机电致发光显示器件相比。稀土配合物有机电致发光器件具有高色纯度发射和高内量子效率的优点。本文概述了稀土配合物分类、稀土配合物有机电致发光器件研究进展和优点，着重研究了稀土离子及其OLED器件的发光机理。     

影响有机及聚合物发光二极管性能的主要因素

分析了影响有机发光二级管性能的主要因素,并对提高电致发光效率、延长器件工作寿命和发光颜色转变的方法作了评述。     

阱内δ掺杂GaSbBi单量子阱红外发光效率的光致发光光谱研究

采用变激发功率红外光致发光(Photoluminescence,PL)光谱方法研究四个不同阱内δ掺杂面密度的GaSb_0.93Bi_0.07/GaSb单量子阱(Single Quantum Well,SQW)及其非掺杂SQW参考样品。通过分析GaSbBi SQW和GaSb势垒/衬底成分的PL强度演化,发现阱内δ掺杂导致红外辐射效率显著降低,相对下降幅度约为33%-75%。进一步分析结果表明,发光效率下降来源于界面恶化引发的“电子损失”和阱内晶格质量下降导致的“光子损失”的共同作用。这一工作有望为稀Bi红外发光器件的性能优化提供帮助。     

基于软刻印技术的微透镜阵列制作

有机电致发光从最初进行的研究直到今天,在许多方面都有了很大的突破,但目前仍存在一些困难,例如器件的寿命就是比较关键的问题.如果器件具有较高的发光效率,便可在出射光子数相同的情况下,减少电子数的注入,从而降低了器件的焦耳热,提高器件的寿命.利用微透镜提高器件的外量子效率可以取得明显的效果.本文利用软刻印技术制作了聚二甲基...     

第二代有机电致发光显示：高功率、超长寿命、低成本OLED器件

第一代有机电致发光器件使用的是底部发光的结构,因而其效率较低,但工作电压却较高,目前,许多具有高效率且使用柔软低成本基板的有机电致发光结构已经制成功。在实现这些优越性能时,电子掺杂传输层起着重要的作用。首先讨论效率非常高的单色和白光Pin型有机电致发光结构,其次展示非常便于进行光学外耦合项部发光有机发光电致发光器件,最后证实Pin型OLED具有非常长的寿命。     

A Twisting Donor‐Acceptor Molecule with an Intercrossed Excited State for Highly Efficient,Deep‐Blue Electroluminescence

In an organic electroluminescent (EL) device, the recombination of injected holes and electrons produces what appears to be an ion‐pair or charge‐transfer (CT) exciton, and this CT exciton decays to produce one photon directly, or relaxes to a low‐lying local exciton (LE). Thus the full utilization of both the energy of the CT exciton and the LE should be a pathway for obtaining high‐efficiency EL. Here, a twisting donor‐acceptor (D‐A) triphenylamine‐imidazol molecule, TPA‐PPI, is reported: its synthesis, photophysics, and EL performance. Prepared by a manageable, one‐pot cyclizing reaction, TPA‐PPI exhibits deep‐blue emission with high quantum yields (90%) both in solution and in the solid state. Fluorescent solvatochromic experiments for TPA‐PPI solutions show a red‐shift of 57 nm (3032 cm^?1) from low‐polarity hexane (406 nm) to high‐polarity acetonitrile (463 nm), accompanied by the gradual disappearance of the vibrational band in the spectra with increased solvent polarity. The photophysical investigation and DFT analysis suggest an intercrossed CT and LE excited state of the TPA‐PPI, originating from its twisting D‐A configuration. This is a rare instance that a CT‐state material shows highly efficient deep‐blue emission. EL characterization demonstrates that, as a deep‐blue emitter with CIE coordinates of (0.15, 0.11), the performance of a TPA‐PPI‐based device is rather excellent, displaying a maximum current efficiency of >5.0 cd A^?1, and a maximum external quantum efficiency of >5.0%, corresponding to a maximum internal quantum efficiency of >25%. The effective utilization of the excitation energy arising from materials with intercrossed‐excited‐state (LE and CT) characters is thought to be beneficial for the improved efficiency of EL devices.     

Influences of Injection Barrier and Mobility on Recombination Rate and Zone in OLEDs

The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of current densities and the recombination rate in organic single layer devices is presented taking into account the charge injection process at each electrode, charge transport and recombination in organic layer. The calculated results indicate that efficient single-layer devices are possible by adjusting the barrier heights at two electrodes and the carrier mobilities. Lowering the barrier heights can improve the electroluminescent（EL） efficiency pronouncedly in many cases, and efficient devices are still possible using an ohmic contact to inject the low mobility carrier, and a contact limited contact to inject the high mobility carrier. All in all, high EL efficiency needs to consider sufficient recombination, enough injected carriers and well transport.     

Luminescent Efficiency in Single-layer Organic Electrophosphorescent Devices

Based on the charge injection and recombination processes and the triplet-triplet annihilation process, a model to calculate the electro.luminescent（EL） efficiency is presented. The influences of the applied electric field on the injection efficiency, recombination efficiency and electroluminescent efficiency are discussed. It is found that： （1） The injection efficiency is increasing while the recombination efficiency is decreasing with the applied electric field increasing. （2） The EL efficiency is enhanced at low electric field slowly but is decreasing at high electric field with the increase of applied voltage. （3） The EL efficiency is decreasing with the increase of the host-guest molecular distance （R）. So, it is concluded that the EL efficiency in single-layer organic electrophosphorescent devices is dominated by injection efficiency at lower electric field and recombination efficiency at higher electric field.     

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。     

Efficient Organic Multi—quantum Well Electroluminescent Devices Using Aluminum as Cathodes

Organic green light emitting devices(LEDs)with multi-quantum well(MQW)structure were fabricated.Aromatic diamine(TPD)was used as holetransporting layer and potential barrier layer;Tris(8-hydroxyquinoline)aluminunum(Alq3)was acted as electron-transporting emitter and MQW green emitter.Airstable aluinum(Al)was used as electron-injection contact.The influence of the thickness of potential barrier layer and the number of quantum well on the electroluminescent(EL)efficiencies of the devices was investigated.The organic LEDs with two quantum wells showed enhanced EL efficiencies.Maximum external quantum efficiency and brightness were 1.04% and 7000cd/m^2,respectively.     

有机小分子掺杂的聚合物共混发光二极管

报道了用可溶性发光材料聚（２,５－二丁氧基苯）做发光材料,分别与母体聚合物聚乙烯基咔唑（ＰＶＫ）和聚甲基丙烯酸甲脂（ＰＭＭＡ）共混,并掺杂电子传输材料叔丁基联苯基苯基口恶二唑和空穴传输材料二胺衍生物作发光层,用铟锡氧化物和铝分别作正负电极,制作了两种蓝紫光有机／聚合物单层发光器件。通过比较两种器件的器件特性,发现以ＰＭＭＡ做母体的器件比用ＰＶＫ做母体的器件有更好的稳定性,器件开启电压为１０Ｖ左右,发光峰值波长均位于４２４ｎｍ,电致发光效率可达２．９％,比用ＰＶＫ做母体的器件效率高一倍多。     

Elucidating the role of current injection on the influence of open-circuit voltage in small-molecule organic photovoltaic devices: From the aspects of charge transfer and electroluminescent spectrum

We demonstrate that the open-circuit voltage (V_OC) of organic photovoltaic (OPV) devices composed of rubrene and C₆₀ can be considerably different when the anode and active layer are changed. Two types of anodes and active layers were compared. In plasma-treated indium-tin-oxide (ITO) OPV devices, the parameter V_OC exhibits an improvement from 0.68 V to 0.76 V when the device structure is varied from a bilayer to a mixed structure. However, in the OPV devices that use ITO/MoO₃ as the anode, a similar V_OC is observed regardless of the device structure. A series of temperature-dependent measurements are conducted to investigate these results. The calculation of barrier height at the rubrene/C₆₀ (or rubrene:C₆₀) interface yields the prediction of V_OC, suggesting that an excess energetic loss occurs in the mixed structures. The electroluminescent (EL) spectra of these devices show that the mixed structure can completely quench the EL of rubrene single layer. A broad band of the charge transfer (CT) emission is observed clearly. A temperature-dependent measurement for the extracting injection barrier is conducted and shows that the mixed structure is favorable for the hole current injection. The CT properties are obtained using the external quantum efficiency and EL spectra of the OPV devices. We find that the nonradiative recombination loss is highly correlated with the injected current; the lower the injection barrier induced the less the nonradiative recombination loss. Therefore, the parameter V_OC can be improved when the injected current is increased.     

1‐Methyl‐2‐(anthryl)‐imidazo[4,5‐f][1,10]‐phenanthroline: A Highly Efficient Electron‐Transport Compound and a Bright Blue‐Light Emitter for Electroluminescent Devices

A new organic blue‐light emitter 1‐methyl‐2‐(anthryl)‐imidazo[4,5‐f][1,10]‐phenanthroline ( 1 ) has been synthesized and fully characterized. The utility of compound 1 as a blue‐light emitter in electroluminescent (EL) devices has been evaluated by fabricating a series of EL devices A where compound 1 functions as an emitter. The EL spectrum of device series A has the emission maximum at 481 nm with the CIE (Commission Internationale de l'Eclairage) color coordinates 0.198 and 0.284. The maximum luminance of devices in series A is 4000 cd m^–2 and the best external quantum efficiency of device series A is 1.82 %. The utility of compound 1 as an electron injection–electron transport material has been evaluated by constructing a set of EL devices B where 1 is used as either the electron‐injection layer or the electron injection–electron transport layer. The performance of device series B is compared to the standard device in which Alq₃ (tris(8‐hydroxyquinoline) aluminum) is used as the electron injection–electron transport layer. The experimental results show that the performance of 1 as an electron injection–electron transport material is considerably better than Alq₃. The stability of device series B is comparable to that of the standard Alq₃ device. The excellent performance of 1 as an electron injection/transport material may be attributed to the strong intermolecular interactions of 1 in the solid state as revealed by single‐crystal X‐ray diffraction analysis. In addition, compound 1 is a colorless material with a much larger highest occupied molecular orbital–lowest unoccupied molecular (HOMO–LUMO) gap than Alq₃, which renders it potentially useful for a wide range of applications in EL devices.     

Influence of Disassociation Probability on External Quantum Efficiency in Organic Electrophosphorescent Devices

An analytical model is presented to calculate the disassociation probability and the external quantum efficiency at high field in doped organic electrophosphorescence（EPH） devices. The charge recombination process and the triplet（T）-triplet（T） annihilation processes are taken into account in this model. The influences of applied voltage and the thickness of the device on the disassociation probability, and of current density and the thickness of the device on the external quantum efficiency are studied thoroughly by including and ignoring the disassociation of excitons. It is found that the dissociation probability of excitons will come close to 1 at high electric field, and the external EPH quantum efficiency is almost the same at low electric field. There is a large discrepancy of the external EPH quantum efficiency at high electric field for including or ignoring the disassociation of excitons.