有机小分子掺杂的聚合物发光二极管电致发光及其发射机制

在新型空穴传输聚合物聚TPD(PTPD)中掺杂电子传输有机小分子荧光染料Rubrene制成薄膜器件.考察了影响聚合物掺杂小分子薄膜器件发光性能的因素.实验表明,通过在器件中掺杂,可以控制器件所发光的颜色.研究了PTPD掺杂Rubrene分子薄膜的电致发光光谱和光致发光光谱.由实验可知.在光致发光中存在从PTPD向Rubrene的能量传递和电荷转移,而电致发光则存在从PTPD向Rubrene的能量传递和Rubrene分子对载流子的俘获.即掺杂器件的发射机制为载流子陷阱和Forster能量转换过程的共同作用.     

聚合物/有机小分子异质结掺杂型电致发光二极管及其发射机制

为了提高有机电致发光器件的效率和稳定性,制作了聚合物/有机小分子异质结掺杂型电致发光二极管.它以新型PTPD(聚TPD)为空穴传输材料,高效荧光材料Rubrene为掺杂剂. 异质结基本结构为PTPD/Alq3,双层掺杂时,器件电致发光的量子效率大约是未掺杂器件的两倍;与未掺杂器件和常用的TPD/Alq3二极管相比,掺杂器件的稳定性有了显著的提高. 从电致发光光谱可知,掺杂器件的发射机制为载流子陷阱和Frster能量转换过程的共同作用.     

聚合物/有机小分子异质结掺杂型电致发光二极管及其发射机制

为了提高有机电致发光器件的效率和稳定性,制作了聚合物/有机小分子异质结掺杂型电致发光二极管.它以新型PTPD(聚TPD)为空穴传输材料,高效荧光材料Rubrene为掺杂剂.异质结基本结构为PTPD/Alq3,双层掺杂时,器件电致发光的量子效率大约是未掺杂器件的两倍;与未掺杂器件和常用的TPD/Alq3二极管相比,掺杂器件的稳定性有了显著的提高.从电致发光光谱可知,掺杂器件的发射机制为载流子陷阱和Forster能量转换过程的共同作用.     

掺杂型异质结有机电致发光二极管及其稳定性

研制了高效率、高稳定性的聚合物／有机物异质结掺杂型电致发光二极管（LED）,它以新型聚合物三苯基二胺衍生物（PTPD）为空穴传输材料,高效荧光材料红荧稀（Rubrene）为掺杂剂,异质结基本结构为PTPD／Alq3。双层掺杂时,器件电致发光（EL）的量子效率为1．47％,大约是未掺杂异质结器件0．74％的2倍;与未掺杂器件和常用的TPD／Alq3二极管相比,掺杂器件的稳定性有了显著的提高。讨论了异质结掺杂型LED稳定性改善机理。     

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。     

掺杂聚合物蓝绿发光二极管

本文报道了用有机染料８－羟基喹啉铝（Ａｌｑ３分散到聚乙烯基咔唑（ＰＶＫ）中的掺杂聚合物作为有源层制作的蓝绿发光二极管（ＬＥＤ），聚合物发光层用旋转涂敷的方法制备．ＩＴＯ／Ａｌｑ３：ＰＶＫ／Ａｌ器件在正向偏压为６Ｖ时可以看到蓝绿发光，峰值波长为５１０ｎｍ，最大亮度为１６８ｃｄ／ｍ２．     

发射偏振光的聚合物发光二极管

发射偏振光的聚合物发光二极管最近用聚合物基器件已首次从发光二极管获得偏振光。这种发光二极管由夹在玻璃衬底两薄膜电极之间的拉伸取代聚噻吩薄膜构成（见下图）。当电流通过聚合物薄膜时，聚合物材料便发光，产生偏振光输出。本研究在Ｏ，Ｉｎ－ｇａｎａｓ指导下由瑞...     

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%．     

有机电致发光器件的Buffer Layer及其金属掺杂

描述了电极与有机层之间的薄层（０．１～１ｎｍ）Ｂｕｆｆｅｒ Ｌａｙｅｒ（缓冲层,特别是ＬｉＦ）对ＯＥＬ器件性能,特别是亮度效率的提高及其增强机制,评述了复合电极及金属掺杂有机物层对ＯＥＬ器件亮度和效率的增强现象。     

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。     

有机发光器件的一种失效机制

制备了结构为铟锡氧化物(ITO)/NPB/插入层/Alq/LiF/Al的有机电致发光(EL)器件,测量了器件发光随电压变化的光谱和电压-电流-亮度特性,观察到这种结构器件在电压升高的过程中总是在某电压附近有一个光谱、亮度和效率等性能突变的不可逆过程,这是由于在发光区域附近的纳米薄层材料将导致电荷在该区域的局部聚集,并引起该薄层材料局部破坏。这一失效的机制表明,尽管在器件制备过程中可能需要在器件中使用几纳米厚的有机层,但是应当考虑尽量避免,以使器件内载流子分布合理,避免此类失效过程发生。     

Understanding the Role of Small Cations on the Electroluminescence Performance of Perovskite Light-Emitting Diodes

The delicate engineering of monovalent cations in perovskite material has led to continuous performance breakthroughs and stability improvement for the perovskite light-emitting diodes (PeLEDs). However, the exact role of A-site cations on the electroluminescence (EL) performance and degradation mechanism of PeLEDs has not been systematically answered yet. Herein, it is demonstrated that the most commonly used methylammonium cation (MA⁺) has an adverse effect on the electrochemical reaction at the interface between perovskite and metal-oxide layer, leading to deteriorated EL performance as compared to that of the formamidinium cation (FA⁺)-based perovskite. It reveals that the accelerated deprotonation process of MA⁺ under an electric field will aggravate the reaction between iodide and metal ion in oxide layer. The further substitution of a small portion of FA⁺ with inorganic cesium cation (Cs⁺) results in much enhanced crystallinity and enlarged crystal size, leading to an optimized peak external quantum efficiency of 21.3%. The ion migration process in the PeLEDs can be significantly suppressed with Cs⁺ incorporation, leading to a smaller roll-off under large current density and an elongated half-lifetime of 190.1 h under a current density of 20 mA cm^-2, representing one of the most stable PeLEDs based on 3D perovskite layer.     

Moiecuiar Doped Poiymer Light Emitting Diodes with Air—stabie Aluminum as Cathode

By using air-stable alumminum as cathode,molecular doped polymer (MDP)blue light emitting diodes(LEDs)were constructed.Poly(N-vinylcarbazole(PVK)doped with,1,1,4,4-tetrapheny 1-1,3-butadiens(TPB)was used as the light-emitting layer,a layer of 2-(4-biphenylyl)-5-(4-terbutypheny)1-3,4-oxadiazole(PBD) as hole-blocking,electron-transporting layer and a layer of tris(8-quinolinolate)-Aluminum(Alq3)film also worked as an electron-transporting layer.The device with structure of ITO/PVK;TPB/PBD/Alq3/Al was fabricated.Blue emis-sion began at about 4V,more than 1000 cd/m^2 was achieved at 14V.This is the lowest turn-on voltage for polymeric lgiht-emitting diodes(PLEDS)used air-stable elec-trodes.Such low-operating voltage,especially using air-stable aluminum as cathode,may be helpful for the devices to be used in commercially viable displays.     

Emission Wavelength Tuning via Competing Lattice Expansion and Octahedral Tilting for Efficient Red Perovskite Light-Emitting Diodes

The band-edge electronic structure of lead halide perovskites (ABX₃) is composed of the orbitals of B and X components and can be tuned through the composition and structure of the BX₆ octahedron. Although A-site cations do not directly contribute to near-edge states, the bandgap of 3D metal halide perovskites can be affected by A-cations through BX₆ octahedron tilting or lattice size variation. Here, as confirmed by the Rietveld refinement results of X-ray diffraction characterization, the competition between lattice expansion and octahedral tilting is identified for the first time in emission wavelength tuning when introducing a large A-site cation (C₂H₅NH₃⁺, EA⁺) into 1-naphthylmethylammonium iodide-passivated CsPbI₃ system. The former dominates spectral redshift, while the latter leads to a blueshift of emission peak, which broadens the way to tune the emission wavelength. In addition, excess cations can also passivate the perovskites, leading to a photoluminescence (PL) quantum yield as high as 61%, increased average PL lifetime of 74.7 ns, and a high radiative and non-radiative recombination ratio of 15.7. Eventually, spectral-stable deep-red perovskite light-emitting diode with a maximum external quantum efficiency of 17.5% is realized, which is one of the highest efficiencies without using any light outcoupling and anti-solvent techniques.     

Molecular Doped Polymer Light Emiting Diodes with Air－stable Aluminum as Cathode

ＭｏｌｅｃｕｌａｒＤｏｐｅｄＰｏｌｙｍｅｒＬｉｇｈｔＥｍｉｔｉｎｇＤｉｏｄｅｓｗｉｔｈＡｉｒ－ｓｔａｂｌｅＡｌｕｍｉｎｕｍａｓＣａｔｈｏｄｅ①②ＣＨＥＮＢａｉｊｕｎ，ＨＯＵＪｉｎｇｙｉｎｇ．ＸＵＥＳｈａｎｈｕａ，ＬＩＵＳｈｉｙｏｎｇ（ＳｔａｔｅＫｅｙ...     

深能级对白光LED的电致发光和I-V特性的影响

为了研究一种无荧光粉的单芯片白光发光二极管(LED)的光电性质,实际测量了它的升温电致发光光谱和升温电流-电压(I-V)特性,并测量了相似结构的蓝光LED以作对比。实验发现白光LED的电致发光光谱中有一个与有源区中的深能级相关的较宽的长波长发光峰,根据这个发光峰的强度与温度之间的依赖关系,通过数据拟合,得到了深能级的平均激活能,约为199 meV。由于有源区中存在大量深能级,也对白光LED的I-V特性产生一定影响,有源区中的深能级成为额外的载流子源,使白光LED的I-V特性表现出独特的性质。