一种新型Ir(Ⅲ)配合物磷光材料的电致发光性能研究

合成了一种新的磷光Ir(Ⅲ)配合物Ir(NCPy)2acac,其中NCPy和acac分别代表9-(2-萘基)-3-吡啶-咔唑和乙酰丙酮。利用该配合物制备了掺杂的有机发光二极管(OLEDs)。其中掺杂器件在513nm处有较强的金属配合物三重态的绿色磷光发射,最大亮度为24340cd/m2,最大电流效率为16.45cd/A,色坐标为(0.26,0.62),是首次报道的新型Ir(Ⅲ)配合物绿色磷光材料。     

以3-乙酰基樟脑为辅助配体的新型聚合物红色磷光器件

以新型环金属Ir(Ⅲ)配合物2-苯并噻吩吡啶(btp)2Ir3-乙酰基樟脑(acam)为磷光发光客体,掺杂在PVK+30%PBD主体材料中,制备了红色聚合物发光器件,同时测试了配合物在溶液中的紫外-可见光(UV-Vis)吸收光谱、光致发光(PL)光谱、PL效率、热稳定性和循环伏安曲线。结果表明,位阻基团acam的引入有效改善了配合物在溶液中的荧光光谱、量子效率。器件的测试结果显示,当掺杂浓度为5%时,电致发光(EL)光谱最大发射峰在623nm,启动电压为7.2V;在15.7V时器件最大亮度为4 127cd/m2,在11.6V时最大亮度效率为4.1cd/A,CIE色坐标值为(0.66,0.32)。     

有机发光二极管中ADN掺杂ErQ的1.54μm电致发光

自行设计了基于8-羟基喹啉铒(ErQ)为发射层(EMLs)和二硝酰胺铵(ADN)为蓝光主体材料的近红外有机发光二级管.器件的基本结构为(p-Si/NPB/EML/Bphen/Bphen:Cs2CO3/Sm/Au),设计并比较了三套不同发射层结构(ErQ/ADN为双层结构器件,(ErQ/ADN)×3为多层结构器件,ErQ:ADN为掺杂结构器件)的器件.三组器件在一定的偏压下,均可发出1.54μm的光,对应三价铒离子4I13/2→4I15/2的跃迁.其中,ADN:ErQ(1∶1)掺杂结构的近红外电致发光强度是ADN/ErQ双层结构中的三倍.此外,不同掺杂浓度的ADN:ErQ复合膜做了以下表征:吸收谱、光致发光谱和荧光寿命谱.实验结果证实了在近红外电致发光过程中存在从ADN主体分子到ErQ发射分子的高效率的能量转移.     

一种正丙基环己烷修饰红光铱(Ⅲ)配合物的合成与发光性能研究

为了提高铱配合物材料的溶解性,同时具有较高的热稳定性,将正丙基环己烷引入到配体中合成了一种新型结构的红色磷光铱(Ⅲ)配合物Ir(pcpiq)₂acac (pcpiq=1-[4-(4-丙基环己基)苯基]异喹啉,acac=乙酰丙酮负离子)。通过紫外-可见光吸收光谱、荧光发射光谱、循环伏安测试和差热扫描分析对其光学性能、电化学性能和热稳定性进行了研究。以其作为发光材料,按照4~12%的掺杂浓度,分别以真空蒸镀和溶液旋涂工艺制备了有机电致发光器件(OLED)。结果显示,以Alq3为主体的蒸镀工艺制备的器件,EL光谱发射峰位于639 nm,亮度达到5 987 cd/m²,10 V电压时电流效率和功率效率分别为6.11 cd/A和1.64 lm/W,器件发出了较纯正的红光,其色坐标位于(0.68,0.32)。     

Tb配合物TbY(o-MOBA)6(phen)2·2H2O的电致发光器件

合成了一类新型稀土配合物TbY(o-MOBA)6(phen)2·2H2O,将其掺杂到导电聚合物聚乙稀咔唑(PVK)中获得了纯正、明亮的绿光发射.用这种掺杂体系分别制作了2类器件:1) ITO/PVK:TbY(o-MOBA)6(phen)2·2H2O/LiF/Al;2) ITO/PVK:TbY(o-MOBA)6(phen)2·2H2O/BCP/AlQ/LiF/Al.器件1的起亮电压为13 V,在21 V时最大亮度为18.2 cd/m2;结构优化的器件2,在23 V 时最大亮度可达124.5 cd/m2.将这种材料的发光性能与另一种稀土配合物Tb(o-MOBA)3phen·H2O相比较,并分别讨论了其光致发光(PL)和电致发光(EL)机理.     

基于Zn(4-TfmBTZ)2的OLED的电致发光光谱调控

将不同浓度的二[2-(4,三氟甲基-2-羟基苯基)](Zn(4-TfmBTZ)2)掺杂到mcp层中制备了有机电致发光器件(OLED),器件的结构为ITO/NPB(40nm)/[Zn(4-TfmBTZ)28%:mcp](30nm)/Bphen(40nm)/LiF(1nm)/Al(200nm)。结果发现,Zn(4-TfmBTZ)2的掺杂浓度极大地影响器件的光谱和色度。在mcp层中,Zn(4-TfmBTZ)2质量分数为8%时,Zn(4-TfmBTZ)2与电子传输层Bphen形成的激基复合物发射较强;但在掺杂浓度达到50%时,激基复合物的发射非常弱,几乎消失。由此通过mcp中Zn(4-TfmBTZ)2掺杂浓度的调节,实现了器件从蓝光色坐标为(0.22,0.27)到白光色坐标为(0.29,0.34)发射的调控。     

基于Zn(Meq)_2为发光和主体材料OLEDs性能的研究

以2-甲基-8-羟基喹啉配体和ZnSO_4·7H_2O合成了有机金属配合物Zn(Meq)_2,并开展了材料的光电特性研究。当双层器件结构为ITO/NPB/Zn(Meq)_2/LiF/Al时,实现了绿光发射,EL峰位位于542 nm,最大亮度和效率分别为7 429 cd/m~2和1.80 cd/A。而当掺杂器件结构为ITO/NPB/Zn(Meq)_2:DCJTB/Alq_3/Li F/Al时,实现了红橙光发射,EL峰位位于580 nm,最大亮度和效率分别为6 075 cd/m~2和1.02 cd/A。结合器件结构和性能,讨论了相关工作机制。     

一种含液晶基元的新型铱配合物的合成与发光性能研究

为了实现溶液化制备有机电致发光器件(OLED),制备和应用具有高溶解性的有机电致发光材料是重要的手段之一。本工作设计和合成了一种含液晶分子中常用的丙基双环己基二氟苯基结构单元的配体及其铱配合物Ir(cfpp)2(acac)(cfpp=2-(2,3-二氟-5-[trans,trans-4′-丙基-(1,1′-双环己基)]苯基)吡啶);acac=乙酰丙酮负离子)。以其作为绿色发光掺杂材料,按照2%、4%和8%的掺杂含量旋涂制备了OLED器件,器件结构为ITO/PEDOT∶PSS/PVK∶PBD∶Ir(cfpp)2(acac)/TPBi/LiF/Al。当掺杂浓度为8%时,器件的最大发射波长为524nm,最大发光亮度达到3 600cd/m2;当电流密度为20mA/cm2时,最大电流效率和功率效率分别为2.0cd/A和0.6lm/W,具有较强的电致发光特性。研究结果表明,应用含液晶结构单元设计和合成高溶解性的有机电致发光材料是可行的研究思路,为制备可旋涂有机电致发光材料提供了新方法。     

光学、显示与发光材料

0632054一种新型双8-羟基喹啉-锌高分子配合物的合成及光致发光性能[刊,中]／文芳岱／／北京化工大学学报(自然科学版)．-2006,33(5)．-46-49(C)采用Witting-Horner反应合成了一种新型双8-羟基喹啉配体．并将此配体与金属锌进行配位反应,制备与其对应的高分子配合物。采用红外、核磁和紫外可见光谱等表征了配体及其配合物的结构和光物理性能,利用荥光光谱研究了高分子配合物的光致发光性能,确定了其最大发射峰位(550nm)。该配合物是一种理想的橙红色发光聚合物材料。参12 0632055 Er3+掺杂Bi2O3-B2O3-Ga2O3玻璃光谱性质及热稳定性研究[刊,中]／聂秋华／／量子电子学报．-2006,23 (5)．-607-612(L) 0632056高双折射光子晶体保偏光纤研究进展[刊,中]／张亚妮／／量子电子学报．-2006,23(5)．-577-582(L)     

Tb(p-MBA)3phen与PVK混合体系发光性质研究

研究了铽配合物Tb(p-MBA)3phen与聚乙烯咔唑PVK共掺杂体系的电致发光(EL)和光致发光(PL)特性。结果发现,在EL中,PVK的发光完全被抑制,只能看到明显的Tb^3 绿光发射;而在PL中,除了Tb^3 发光外,还可以看到明显的PVK发光。这是由于两种发光机理不同造成的。通过测量材料的发射光谱和激发光谱,初步探讨了器件的发光机理,认为Tb^3 的发光可能来源于2个方面：1)PVK到稀土配合物的Foerester能量传递;2)PVK作为一种空穴传输材料,而稀土配合物作为电子陷阱,受激的空穴和电子直接被稀土配合物俘获,在稀土配合物上形成激子复合发光。所制作的单层器件的最大亮度达24．8cd／m^2。     

Interface Functionalities in Multilayer Stack Organic Light Emitting Transistors (OLETs)

Herein is described a multidisciplinary approach to understand the performance limitations of small molecule organic light emitting transistors (OLETs) based on a layered architecture, an innovative architecture potentially competitive with the state of the art and more flexible for spectral emission control. The processes of charge injection and field‐effect transport at metal/organic and organic/organic interfaces are analysed using microscopic and spectroscopic techniques in coordination. Atomic force microscopy and ultrasonic force microscopy are employed to characterize the interface morphology and the initial growth stages of organic films where charge transport actually occurs. X‐ray diffraction and near edge X‐ray dichroic absorption with linearly polarised light allow to determine the unit cell packing and the molecular orientation at the active organic interfaces, as well as the amount of non‐ordered domains. Moreover, chemical reactivity at the interfaces is measured by X‐ray photoelectron spectroscopy. It is found that a strong reaction occurs at the metal‐organic interfaces, with molecular fragmentation. Additionally, the transport properties strongly depend on the nature of the materials forming the organic stack. Specifically, amorphous conjugated films as bottom layers can promote an increased molecular disorder in the upper active layer, with a concomitant deterioration of the conduction properties.     

有机半导体器件的现状及发展趋势

从上世纪末和本世纪初开始,有机半导体材料研究引起了业界的广泛重视,使有机半导体器件的实验室制作水平得到大幅提高,并逐步进入当前的商品发展阶段。概述了有机半导体的发展历程、各种器件结构与特性及其技术现状;介绍了有机发光二极管(OLED)、太阳电池以及其他有机半导体器件的应用概况;探讨了有机半导体优于Si和GaAs等典型无机半导体技术的特点,分析讨论了有机半导体技术的发展前景;指出有机半导体器件有望成为解决传统半导体技术问题的有效途径。     

Highly Crystalline Rubrene Light-Emitting Diodes with Epitaxial Growth

Conventional organic optoelectronic devices suffer from low carrier mobility limited by the static and dynamic disorder. Organic crystals with long-range order can circumvent the effects of disorder and significantly improve the charge transport. While highly ordered organic crystals offer the desirable electronic coupling strength and charge transport, their integration into large-area optoelectronic devices remains a challenge. Here, monolithic integrated triclinic crystal rubrene light-emitting diodes (LEDs) are presented using epitaxial growth with functional additives being engineered into the films. Superior charge transport, excellent operational and long-term stability in these light-emitting devices are demonstrated. By comparing two rubrene-based LEDs, one made from amorphous and one from crystalline rubrene layers, their exciton dynamics are estimated using comprehensive transient electroluminescence simulation. The crystalline LEDs show high triplet-triplet annihilation (TTA) rate constant similar to TTA rate constant of triclinic single crystals determined by optical spectroscopy. At the same time, the crystalline phase enhances drastically the singlet-fission and bimolecular annihilation rates, which reduces the overall performance of the LED compared to its amorphous counterpart. Finally, an outlook on the potential applications of rubrene and/or its derivatives crystalline films are provided for enhancing the performance of organic and hybrid optoelectronic devices.     

Interface Engineering for Organic Electronics

The field of organic electronics has been developed vastly in the past two decades due to its promise for low cost, lightweight, mechanical flexibility, versatility of chemical design and synthesis, and ease of processing. The performance and lifetime of these devices, such as organic light‐emitting diodes (OLEDs), photovoltaics (OPVs), and field‐effect transistors (OFETs), are critically dependent on the properties of both active materials and their interfaces. Interfacial properties can be controlled ranging from simple wettability or adhesion between different materials to direct modifications of the electronic structure of the materials. In this Feature Article, the strategies of utilizing surfactant‐modified cathodes, hole‐transporting buffer layers, and self‐assembled monolayer (SAM)‐modified anodes are highlighted. In addition to enabling the production of high‐efficiency OLEDs, control of interfaces in both conventional and inverted polymer solar cells is shown to enhance their efficiency and stability; and the tailoring of source–drain electrode–semiconductor interfaces, dielectric–semiconductor interfaces, and ultrathin dielectrics is shown to allow for high‐performance OFETs.     

Redox‐Stability of Alkoxy‐BDT Copolymers and their Use for Organic Bioelectronic Devices

Organic semiconductors can be employed as the active layer in accumulation mode organic electrochemical transistors (OECTs), where redox stability in aqueous electrolytes is important for long‐term recordings of biological events. It is observed that alkoxy‐benzo[1,2‐b:4,5‐b′]dithiophene (BDT) copolymers can be extremely unstable when they are oxidized in aqueous solutions. The redox stability of these copolymers can be improved by molecular design of the copolymer where it is observed that the electron rich comonomer 3,3′‐dimethoxy‐2,2′‐bithiophene (MeOT2) lowers the oxidation potential and also stabilizes positive charges through delocalization and resonance effects. For copolymers where the comonomers do not have the same ability to stabilize positive charges, irreversible redox reactions are observed with the formation of quinone structures, being detrimental to performance of the materials in OECTs. Charge distribution along the copolymer from density functional theory calculations is seen to be an important factor in the stability of the charged copolymer. As a result of the stabilizing effect of the comonomer, a highly stable OECT performance is observed with transconductances in the mS range. The analysis of the decomposition pathway also raises questions about the general stability of the alkoxy‐BDT unit, which is heavily used in donor–acceptor copolymers in the field of photovoltaics.     

基于6,13-二氯并五苯微纳米带的高性能有机光控晶体管

有机光控晶体管因其低成本、易加工等特点而受到广泛的关注。通过溶剂氛围滴膜法制备了基于6,13-二氯并五苯的微纳米带。采用氯苯做溶剂时,得到了形貌规则、晶形良好的微纳米带,而采用邻二氯苯做溶剂时,获得了大面积有序、定向生长的微纳米带。随后构筑了基于上述微纳结构的单根和多根微纳米带有机光控晶体管,器件显示了高的光敏特性。在很低强度的入射光(1.55mW/cm2)照射下,其光敏系数达1 300,表明6,13-二氯并五苯在有机微纳光控晶体管方面具有很好的应用前景。     

Epindolidiones—Versatile and Stable Hydrogen‐Bonded Pigments for Organic Field‐Effect Transistors and Light‐Emitting Diodes

Hydrogen‐bonded pigments are remarkably stable high‐crystal lattice energy organic solids. Here a lesser‐known family of compounds, the epindolidiones, which demonstrates electronic transport with extraordinary stability, even in highly demanding aqueous environments, is reported. Hole mobilities in the range 0.05–1 cm² V^–1 s^–1 can be achieved, with lower electron mobilities of up to 0.1 cm² V^–1 s^–1. To help understand charge transport in epindolidiones, X‐ray diffraction is used to solve the crystal structure of 2,8‐difluoroepindolidione and 2,8‐dichloroepindolidione. Both derivatives crystallize with a linear‐chain H‐bonding lattice featuring two‐dimensional π–π stacking. Powder diffraction indicates that the unsubstituted epindolidione has very similar crystallinity. All types of epindolidiones measured here display strong low‐energy optical emission originating from excimeric states, which coexists with higher‐energy fluorescence. This can be exploited in light‐emitting diodes, which show the same hybrid singlet and low‐energy excimer electroluminescence. Low‐voltage FETs are fabricated with epindolidione, which operate reliably under repeated cyclic tests in different ionic solutions within the pH range 3–10 without degradation. Finally, in order to overcome the insolubility of epindolidiones in organic solvents, a chemical procedure is devised to allow solution‐processing via the introduction of suitable thermolabile solubilizing groups. This work shows the versatile potential of epindolidione pigments for electronics applications.     

Insulating Electrets Converted from Organic Semiconductor for High-Performance Transistors,Memories, and Artificial Synapses

Electrets are commonly used charged insulators that generate a quasi-permanent electric field. However, when conventional electrets come into direct contact with semiconductors, the energy level mismatch at the interface results in low memory speed and high energy consumption of electret devices due to both charge injection and storage being non-conducive. To address this, the n-type semiconductor N,N′-dioctyl-3,4,9,10-perylene tetracarboxylic diimide (C₈-PTCDI) is converted to C₈-PTCDI (D) via oxygen degradation. The resulting C₈-PTCDI (D) electrets, when charged using an electric field and/or light, retain the energy level of the n-type semiconductors to facilitate charge trapping. They also exhibit deeper trap energy levels and increased trap density, thereby enhancing the sheet charge density of C₈-PTCDI (D) electrets (7.47 × 10¹² cm⁻²). As a result, devices based on n-type electrets demonstrate lower operation voltage (2 V) of transistors, lower operation voltage (20 V) of memories, and lower energy consumption (3.5 fJ per spike) of artificial synapses compared to those without n-type electrets.     

Polymorphism in Non-Fullerene Acceptors Based on Indacenodithienothiophene

Organic solar cells incorporating non-fullerene acceptors (NFAs) have reached remarkable power conversion efficiencies of over 18%. Unlike fullerene derivatives, NFAs tend to crystallize from solutions, resulting in bulk heterojunctions that include a crystalline acceptor phase. This must be considered in any morphology-function models. Here, it is confirmed that high-performing solution-processed indacenodithienothiophene-based NFAs, i.e., ITIC and its derivatives ITIC-M, ITIC-2F, and ITIC-Th, exhibit at least two crystalline forms. In addition to highly ordered polymorphs that form at high temperatures, NFAs arrange into a low-temperature metastable phase that is readily promoted via solution processing and leads to the highest device efficiencies. Intriguingly, the low-temperature forms seem to feature a continuous network that favors charge transport despite of a poorly order along the π–π stacking direction. As the optical absorption of the structurally more disordered low-temperature phase can surpass that of the more ordered polymorphs while displaying comparable—or even higher—charge transport properties, it is argued that such a packing structure is an important feature for reaching highest device efficiencies, thus, providing guidelines for future materials design and crystal engineering activities.     

有机显示浮出水面

介绍了有机显示技术的优势及其应用领域。