双层有机电致发光器件中的激基复合物发射及特性

以两种常用的芳香二胺TPD和NPB为空穴传输材料(HTM)和BBOT为电子传输材料组成双层器件,获得了相对于组成材料的荧光光谱红移和宽化的电致发光.用光致发光表征了这种发射来自激基复合物,并用器件的能级图说明激基复合物的类型为BBOT的激发态BBOT^*与基态的HTM相互作用的复合物.比较TPD和NPB的分子结构和能级表明,分子具有有利的构型和取向比合适的能级更容易形成激基复合物.     

一种新型苯乙烯衍生物的光致发光与电致发光

对一种新型苯乙烯衍生物的光致发光和电致发光进行了研究。１－９－蒽基－４－氯甲基－２,５－二甲氧基苯的溶液随浓度的增大,其单体荧光逐渐减弱而激基复合物发光逐渐增强。在薄膜状态只有激基复合物荧光,表明在溶液和薄膜状态下均存在单体向激基复合物的能量转移过程,用分子间距离越近,能量转移效率越高。以该化合物制成的单层二极管器件,其电致发光光谱随电压增强从激基复合物发光逐渐转变为激复合发光。     

基于激子和电致激基复合物双重发光的白光OLED

基于四苯基乙烯衍生物设计合成了两种蓝光材料TPE-4Br和TPE-3Br,并将其作为有机发光二极管(OLED)器件的发光层,研究发现其可与合适的邻层(空穴传输层/电子传输层)形成电致激基复合物。利用材料的本征激子发光及其电致激基复合物发光,可以得到理想的白光电致发光。将TPE-4Br和TPE-3Br掺杂于mCP中作为发光层,以TAPC和TmPyPB分别作为空穴传输层和电子传输层分别制备器件A和器件B,所得器件在操作电压为9 V时的色坐标分别为(0.32,0.33)和(0.31,0.34)。其中器件B的最大亮度和最大电流效率分别为364.66 cd?m~(-2)与0.79 cd?A~(-1)。     

基于氰基化9-苯基芴衍生物的激基复合物发光与性质研究

激基复合物发光器件因给、受体材料掺杂比例易调且易实现小的单线态-三线态能隙差等优势, 在发展工艺简单、性能高效的有机发光二极管方面显示出很大的应用潜力. 针对目前激基复合物受体材料的种类仍较为匮乏, 器件性能仍需改善等问题, 本工作设计合成出新型基于9-苯基芴的电子受体材料(TCNDPFCz)用于构筑激基复合物发光器件. 实验表明, 受体分子TCNDPFCz与给体分子1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC)掺杂后(TAPC: TCNDPFCz)呈现明显的激基复合物发光, 其光致发光效率为54%, 电流效率为27.2 cd•A^‒1, 功率效率为32.9 lm•W^‒1, 外量子效率为12.5%. 经分析, 我们推测激基复合物TAPC:TCNDPFCz形成的过程得益于TCNDPFCz具有很强的吸电子能力. 本工作表明9-苯基芴可以作为骨架单元来构筑受体分子, 为开发新型电子受体材料提供了新策略.     

以膦酸酯聚芴作为阴极界面修饰层的高效聚合物红光电致发光器件

以膦酸酯聚芴为阴极界面修饰层, 高功函金属铝为阴极, 制备了一种高效聚合物红光电致发光器件. 通过X射线光电子能谱(XPS)的表征, 分析了经真空蒸镀沉积在膦酸酯聚芴表面的Al原子与下层的膦酸酯聚芴在有机物-金属界面处的作用情况, 结果表明, 在真空蒸镀金属Al的过程中, 在有机物-金属界面处形成了一种氧/铝复合物. 研究了这种氧/铝复合物对器件光电性能的影响, 结果表明, 氧/铝复合物的产生提高了阴极电子的注入, 使器件效率得到了很大提高. 与以Ca/Al为阴极的传统器件相比, 以膦酸酯聚芴/Al为阴极的聚合物电致发光器件的效率提高了75%, 达到7.0 cd/A.     

利用激基复合物发光的有机白光器件制备

以1,4-二(2-氰基-2-苯乙烯基)-2,5-二苯基苯(CNDPDSB)为发光层, N,N'-[3-萘基]-N,N'-二苯基[1,1'-二苯基]-4,4'-二胺(NPB)为空穴传输层, 8-羟基喹啉铝(Alq)为电子传输层, 制备了一种色度稳定的有机电致白光器件. 该器件的白光发射是由CNDPDSB与NPB界面形成的激基复合物发出的红光以及NPB与CNDPDSB发射的蓝光混合而成. 该白光器件的光谱稳定, 在工作电压(6~13 V)内, 色坐标由(0.33, 0.34)变化到(0.31, 0.37). 器件在6 V电压下开启, 10 V电压下的亮度和效率分别为1200 cd/m2和0.2 cd/A.     

基于三萘苯的溶液可加工螺旋形寡聚物的合成及其在蓝光有机电致发光器件中的应用

近年来,人们在有机电致发光材料和器件结构方面取得了巨大的进步。然而由于蓝光材料具带隙宽的内禀属性,在发光效率、色纯度和稳定性上仍然面临巨大挑战。本文将螺旋形三萘苯共轭体系引入电致发光材料领域,它独特的螺旋形分子结构和易于化学修饰的特点有利于抑制聚集体和基激缔合物的形成。通过SiCl₄催化的环三缩合反应和Suzuki偶联反应,我们设计合成了以三萘基苯为核心,萘、蒽和三苯胺为取代基团的系列螺旋形蓝光寡聚物,并系统地研究了它们的热学、光物理和电化学性质。研究发现,萘和三苯胺取代的寡聚物1, 3, 5-三(3-(1-甲氧基萘-2-基)-4-甲氧基萘-1-基)苯(TNNB)和1, 3, 5-三(3-(4-(N, N-二苯胺基)苯基)-4-甲氧基萘-1-基)苯(TPANB)具有最好的热稳定性。在溶液中,这两种材料都具有深蓝发射,发射峰分别为382和415 nm;在薄膜中, TNNB的发射峰仅有1 nm的红移,而TPANB甚至产生了6 nm的蓝移。以这些寡聚物为发光材料,通过旋涂法制备的有机电致发光器件结果表明,基于TNNB的器件获得了最大亮度达到5273 cd·m^-2,色坐标(0.17, 0.11)的纯蓝光器件。     

含腈基的三苯胺基二苯乙烯化合物的合成及其电致发光性能研究

本文成功地合成了集空穴传输基团三苯胺和电子受体基团腈基于一个分子中的腈基取代的三苯胺基二苯乙烯系列化合物,获得电子和空穴都能够高效注入和传输的新型电致发光材料.由这种材料制备的电致发光器件的性能稳定,启动电压显著降低,发光为黄绿色.     

抗菌医药左氧氟沙星在有机电致发光二极管中的应用

左氧氟沙星(LOFX)是一种知名的抗菌药物, 它的价格非常便宜, 且有成熟的合成和纯化技术. 本文中首次将LOFX作为一种蓝光发光材料和电子传输材料应用于有机电致发光器件(OLED)中. 通过热重分析、UVVis吸收光谱、发射光谱以及循环伏安曲线详细地表征了LOFX的热学及光物理特性. LOFX有高的分解温度,为327 ℃; HOMO、LUMO能级分别为-6.2 和-3.2 eV, 光学带隙为3.0 eV. 以LOFX作为客体材料, 掺杂在主体材料4,4'-二(9-咔唑)联苯(CBP)中制备了蓝光OLED, 该器件的电致发光(EL)发射峰位于452 nm, 最大亮度为2315 cd·m^-2. 进一步, 选择8-羟基喹啉铝(Alq₃)作为参考材料, 分别以LOFX和Alq₃作为电子传输材料制备了结构相同的单载流子器件和绿色磷光OLED. 在相同的电压下, 以LOFX作为电子传输材料的单载流子器件的电流密度比以Alq₃作为电子传输材料的单载流子器件更高. 同时, 以LOFX作为电子传输材料的绿色磷光OLED获得更高的器件效率. 从这些EL性能可以看出, LOFX同时也是一很好的电子传输材料.     

稀土配合物Tb(p-MBA)3phen的有机电致发光

合成了一种新型的稀土铽配合物材料Tb(p-MBA)3phen,把它作为发光材料应用于有机电致发光中.把铽配合物掺杂在导电聚合物PVK中采用旋涂法制得发光层,并利用AlQ作为电子传输层制作了单层、双层有机电致发光器件:器件1(ITO/PVK):Tb(p-MBA)3phen/Al;器件2(ITO/PVK):Tb(p-MBA)3phen/AlQ/LiF/Al,得到了纯正的、明亮的Tb3 离子的绿光发射,4个特征峰分别对应着能级5D4到7Fj(j=6,5,4,3)的跃迁,而PVK的发光完全被抑制.研究了两种器件的电致发光性能,并通过选择AlQ的厚度得到了发光性能较好的器件,其最大亮度在20 V时达到152 cd·m-2.     

Synthesis, photophysical and electroluminescent properties of novel naphthalimide derivatives containing an electron-transporting unit

A series of naphthalimide derivatives containing a benzoazole unit (benzothiazole, benzoxazole or benzimidazole) as electron-transporting unit was designed and synthesized, and their photophysical and electroluminescent properties were investigated. The key design of molecular structures included the use of carrier-transporting fragments, together with twisted molecular conformation that could eliminate the recrystallization tendency and favour the formation of a stable amorphous state. ITO/NPB/emissive layer/Mg∶Ag/Ag bilayer electroluminescent devices were fabricated. Green or yellow-green electroluminescence was obtained successfully with peak emission in the range 530–560 nm.     

The Importance of Excited‐State Energy Alignment for Efficient Exciplex Systems Based on a Study of Phenylpyridinato Boron Derivatives

Understanding excited‐state dynamics is critical for improving the photoluminescence (PL) efficiency of exciplexes. A series of exciplexes based on conventional hole‐transporting materials as donor and newly developed phenylpyridinato boron derivatives as acceptor were investigated. High PL efficiencies were achieved in only some combinations, and a large difference in performance among combinations provided insight into nonradiative processes in exciplex systems. Furthermore, the triplet local excited states (³LE) of each donor and acceptor were found play an important role in triplet exciplex harvesting. Significant contributions from triplets were clearly observed when the charge‐transfer excited states (¹CT and ³CT) and ³LE were ideally aligned. We also demonstrated fine control of relative energy alignment via the concentration to improve the PL efficiency.     

Facile Synthesis of a Furan–Arylamine Hole‐Transporting Material for High‐Efficiency,Mesoscopic Perovskite Solar Cells

A novel hole‐transporting molecule (F101) based on a furan core has been synthesized by means of a short, high‐yielding route. When used as the hole‐transporting material (HTM) in mesoporous methylammonium lead halide perovskite solar cells (PSCs) it produced better device performance than the current state‐of‐the‐art HTM 2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD). The F101‐HTM‐based device exhibited both slightly higher J_sc (19.63 vs. 18.41 mA cm^?2) and V_oc (1.1 vs. 1.05 V) resulting in a marginally higher power conversion efficiency (PCE) (13.1 vs. 13 %). The steady‐state and time‐resolved photoluminescence show that F101 has significant charge extraction ability. The simple molecular structure, short synthesis route with high yield and better performance in devices makes F101 an excellent candidate for replacing the expensive spiro‐OMeTAD as HTM in PSCs.     

Synthesis and properties of σ–π conjugated alternating polymers consisting of carbazole and organosilicon units

We have synthesized novel σ–π conjugated polymers with an alternating organosilanylene and π‐electron system, intending to utilize them for hole‐transporting materials of electroluminescent (EL) devices. 3,6‐Di(lithioethynyl)carbazoles were co‐polymerized with organodichlorosilanes to give the corresponding polymers with molecular weights of M_W = 2000–5000. Another type of polymer with a thienylene unit was also synthesized by the nickel‐catalyzed reaction of the di‐Grignard reagent of 1,2‐bis[2‐(5‐bromothienyl)]tetraethyldisilane with 3,6‐dibromocarbazole, the molecular weight being M_n = 3100. The EL devices with a double‐layer system composed of tris(8‐quinolinolato)aluminum(III) and the present polymers as the emitting‐electron‐transporting and hole‐transporting layers, respectively, emit green EL with a maximum intensity of the order of 10³ cd m^?2. Of these, the device with the thienylene–carbazole polymers exhibited the highest luminance of 1480 cd m^?2. Copyright © 2001 John Wiley & Sons, Ltd.     

Inexpensive Hole‐Transporting Materials Derived from Tröger's Base Afford Efficient and Stable Perovskite Solar Cells

The synthesis of three enamine hole‐transporting materials (HTMs) based on Tröger's base scaffold are reported. These compounds are obtained in a three‐step facile synthesis from commercially available materials without the need of expensive catalysts, inert conditions or time‐consuming purification steps. The best performing material, HTM3, demonstrated 18.62 % PCE in PSCs, rivaling spiro‐OMeTAD in efficiency, and showing markedly superior long‐term stability in non‐encapsulated devices. In dopant‐free PSCs, HTM3 outperformed spiro‐OMeTAD by a factror of 1.6. The high glass‐transition temperature (T_g=176 °C) of HTM3 also suggests promising perspectives in device applications.     

3,4‐Phenylenedioxythiophene (PheDOT) Based Hole‐Transporting Materials for Perovskite Solar Cells

Two new electron‐rich molecules based on 3,4‐phenylenedioxythiophene (PheDOT) were synthesized and successfully adopted as hole‐transporting materials (HTMs) in perovskite solar cells (PSCs). X‐ray diffraction, absorption spectra, photoluminescence spectra, electrochemical properties, thermal stabilities, hole mobilities, conductivities, and photovoltaic parameters of PSCs based on these two HTMs were compared with each other. By introducing methoxy substituents into the main skeleton, the energy levels of PheDOT‐core HTM were tuned to match with the perovskite, and its hole mobility was also improved (1.33×10^?4 cm² V^?1 s^?1, being higher than that of spiro‐OMeTAD, 2.34×10^?5 cm² V^?1 s^?1). The PSC based on MeO‐PheDOT as HTM exhibits a short‐circuit current density (J_sc) of 18.31 mA cm^?2, an open‐circuit potential (V_oc) of 0.914 V, and a fill factor (FF) of 0.636, yielding an encouraging power conversion efficiency (PCE) of 10.64 % under AM 1.5G illumination. These results give some insight into how the molecular structures of HTMs affect their performances and pave the way for developing high‐efficiency and low‐cost HTMs for PSCs.     

Synthesis and properties of novel σ–π alternating polymers with triphenylamine and organosilicon units

We have synthesized novel σ–π conjugated polymers with N,N‐bis(p‐ethynylphenyl)‐N‐(p‐tolyl)amine as the π‐unit. The electroluminescent devices, with a double‐layer system composed of Alq and the present polymers as the emitting‐electron‐transporting and hole‐transporting layers respectively, emit green electroluminescence with a maximum intensity of 760 cd m^?2. Copyright © 2001 John Wiley & Sons, Ltd.     

Copoly(p‐phenylene)s containing bipolar triphenylamine and 1,2,4‐triazole groups: Synthesis,optoelectronic properties,and applications

Two novel copoly(p‐phenylene)s ( P1 – P2 ) containing bipolar groups (12.8 and 6.8 mol %, respectively), directly linked hole transporting triphenylamine and electron transporting aromatic 1,2,4‐triazole, were synthesized to enhance electroluminescence (EL) of poly(p‐phenylene vinylene) (PPV) derivatives. The bipolar groups not only enhance thermal stability but also promote electron affinity and hole affinity of the resulting copoly(p‐phenylene)s. Blending the bipolar copoly‐(p‐phenylene)s ( P1 – P2 ) with PPV derivatives ( d6‐PPV ) as an emitting layer effectively improve the emission efficiency of its electroluminescent devices [indium tin oxide (ITO)/poly(3,4‐ethylenedioxythiophene) (PEDOT):poly(styrenesulfonate) (PSS)/polymer blend/Ca (50 nm)/Al (100 nm)]. The maximum luminance and maximum luminance efficiency were significantly enhanced from 310 cd m^?2 and 0.03 cd A^?1 ( d6‐PPV ‐based device) to 1450 cd m^?2 and 0.20 cd A^?1 (blend device with d6‐PPV / P1 = 96/4 containing ～0.5 wt % of bipolar groups), respectively. Our results demonstrate the efficacy of the copoly(p‐phenylene)s with bipolar groups in enhancing EL of PPV derivatives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Non-amine-based furan-containing oligoaryls as efficient hole transporting materials

A new class of highly stable furan-based hole transporting oligomeric materials, synthesized from the corresponding propargylic dithioacetals, serve as efficient hole transporting materials in electroluminescent devices. The performance of the devices using these furan materials is comparable with or somewhat better than those employing the conventional triarylamines (e.g. alpha-NPD).     

Electroluminescent properties of a partially‐conjugated hyperbranched poly(p‐phenylene vinylene)

In this paper, the electroluminescent properties of a new partially‐conjugated hyperbranched poly (p‐phenylene vinylene) (HPPV) were studied. The single layer light‐emitting device with HPPV as the emitting layer emits blue‐green light at 496 nm, with a luminance of 160 cd/m² at 9 V, a turn‐on voltage of 4.3 V and an electroluminescent efficiency of 0.028 cd/A. By doping an electron‐transport material [2‐(4‐biphenylyl)‐5‐phenyl‐1,3,4‐oxadiazole, PBD] into the emitting layer and inserting a thin layer of tris(8‐hydroxy‐quinoline)aluminum (Alq₃) as electron transporting/hole blocking layer for the devices, the electroluminescent efficiency of 1.42 cd/A and luminance of 1700 cd/m² were achieved. The results demonstrate that the devices with the hyperbranched polymers as emitting material can achieve high efficiency through optimization of device structures. Copyright © 2006 John Wiley & Sons, Ltd.