蓝色有机电致磷光主体材料

有机电致发光(OLEDs)因其具有驱动电压低、主动发光、亮度高、视角宽、响应快、耐冲击与震动等特点,在平板显示与照明领域有着广阔的应用前景。磷光有机电致发光二极管(PhOLEDs)由于能够同时利用三重态和单重态激子,内量子效率从理论上可达到100%,从而克服了传统荧光OLEDs只利用单重态激子时效率25%的限制,在过去的几十年里受到业内人士的极大关注。但要实现三重态磷光,通常需要将重金属原子与主体材料进行掺杂,而重金属配合物的磷光寿命相对较长,容易引起浓度猝灭和三重态-三重态湮灭,所以需要找到合适的主体材料与重金属的磷光发射体进行掺杂来减少上述因素的影响从而得到高性能的电致磷光器件。本文综述了近年来国内外蓝色有机电致磷光主体材料的研究状况,并对空穴传输型、电子传输型和双极传输型的蓝色磷光主体材料按照官能团的不同进行了分类总结和评述,并对其光物理性质、热学性质、电化学性质及器件性能等作了详细归纳比较,最后展望了蓝色有机电致磷光主体材料的前景和发展趋势。     

金属有机电致磷光材料研究进展

综述了近几年来用于有机发光二极管中的金属有机电致磷光材料的研究进展, 重点评述了重金属铱配合物、稀土元素配合物和含金属配合物的聚合物磷光材料近年来的研究进展, 展望了金属有机配合物电致磷光材料的发展前景.     

有机电致磷光材料的分子设计：从主体材料到客体材料

有机电致磷光器件的设计和利用，可以突破由三线态激子跃迁自旋禁阻引起的有机电致荧光器件量子效率的限制。本文综述了有机电致磷光器件和材料的研究进展，主要介绍了主体材料和客体材料的研究现状，特别是蓝光磷光器件主客体材料的研究情况。     

以铱为内核的有机电致磷光材料

有机电致磷光材料可以同时利用单线态和三线态激子发光,具有发光效率高等优点,成为近年来研究的热点.本文综述了以铱为内核的有机电致磷光材料的研究进展、存在问题和研究趋势,并简要介绍了用于制作有机磷光器件的主体材料.     

以铱为内核的有机电致磷光材料

有机电致磷光材料可以同时利用单线态和三线态激子发光,具有发光效率高等优点,成为近年来研究的热点。本文综述了以铱为内核的有机电致磷光材料的研究进展、存在问题和研究趋势,并简要介绍了用于制作有机磷光器件的主体材料。     

以铱为内核的有机电致磷光材料

有机电致磷光材料可以同时利用单线态和三线态激子发光,具有发光效率高等优点,成为近年来研究的热点。本文综述了以铱为内核的有机电致磷光材料的研究进展、存在问题和研究趋势,并简要介绍了用于制作有机磷光器件的主体材料。     

基于咔唑-三唑的新型主体材料及天蓝光有机电致磷光器件

本研究针对蓝光主体材料相对缺乏的现状,利用有机电致磷光器件高效率的优势,选择1,2,4-三唑为电子传输功能基团、咔唑为空穴传输功能基团,设计、制备了新型主体材料oCzTz。通过邻位取代方式实现了分子立体构型高度扭曲,从而使分子的三重态能量达到3.01eV;oCzTz具有较高的热分解温度(353℃)和玻璃化转变温度(110℃);量化计算显示,分子的前线轨道在咔唑和三唑基团之间高度分离。以oCzTz为主体、以FIrpic为发光客体的天蓝光电致磷光器件启亮电压为3.4V,电流效率和功率效率分别高达37.2cd·A-1和29.2lm·W-1,是以TPBI为电子传输层的同类器件的最高效率之一。     

掺杂发光有机电致磷光器件工作原理及主体材料

本文总结了基于掺杂发光的有机电致磷光器件(PhOLED)中磷光材料被激发的途径及机理,并指出不同主体材料对器件性能的不同影响.全面介绍了小分子主体材料研究的新进展及它们在PhOLEDs器件中的运用.比较和讨论了基于各种不同性质主体材料的器件性能,指出主体材料选择策略.同时讨论了各类主体材料的分子结构、热稳定性、三线态能级、载流子迁移率及HOMO/LUMO能级之间的关系,揭示了上述特性对器件性能影响.     

基于磷光发射的有机电致白光器件的研究进展

由于旋轨偶合作用,磷光材料可以同时利用单线态和三线态激子,将其应用于电致白光器件的制作,能够显著提高器件的效率。本文根据磷光电致白光器件结构的不同,综述了国内外在磷光白光电致发光器件领域研究的主要进展。     

位阻型有机电致磷光材料的研究进展

重金属旋轨耦合作用使磷光有机发光二极管的内量子效率在理论上可达100%,突破了传统有机荧光二极管内量子效率为25%的限制,是目前最有潜力的第三代显示器.但是,磷光材料常因浓度猝灭、三线态湮灭、二聚体发光等因素影响器件性能.位阻型磷光材料能够抑制分子间的强相互作用,从而解决了上述问题.本文作者综述了近年来具有大体积空间位阻效应的铱(III)、铂(II)、锇(II)等有机小分子磷光材料的研究进展,讨论了其目前存在的问题和未来的发展趋势.     

Pyridinyl-Carbazole Fragments Containing Host Materials for Efficient Green and Blue Phosphorescent OLEDs

Pyridinyl-carbazole fragments containing low molar mass compounds as host derivatives H1 and H2 were synthesized, investigated, and used for the preparation of electro-phosphorescent organic light-emitting devices (PhOLEDs). The materials demonstrated high stability against thermal decomposition with the decomposition temperatures of 361–386 °C and were suitable for the preparation of thin amorphous and homogeneous layers with very high values of glass transition temperatures of 127–139 °C. It was determined that triplet energy values of the derivatives are, correspondingly, 2.82 eV for the derivative H1 and 2.81 eV for the host H2. The new derivatives were tested as hosts of emitting layers in blue, as well as in green phosphorescent OLEDs. The blue device with 15 wt.% of the iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) emitter doping ratio in host material H2 exhibited the best overall characteristics with a power efficiency of 24.9 lm/W, a current efficiency of 23.9 cd/A, and high value of 10.3% of external quantum efficiency at 100 cd/m². The most efficient green PhOLED with 10 wt% of Ir(ppy)₃ {tris(2-phenylpyridine)iridium(III)} in the H2 host showed a power efficiency of 34.1 lm/W, current efficiency of 33.9 cd/A, and a high value of 9.4% for external quantum efficiency at a high brightness of 1000 cd/m², which is required for lighting applications. These characteristics were obtained in non-optimized PhOLEDs under an ordinary laboratory atmosphere and could be improved in the optimization process. The results demonstrate that some of the new host materials are very promising components for the development of efficient phosphorescent devices.     

Asymmetric Host Molecule Bearing Pyridine Core for Highly Efficient Blue Thermally Activated Delayed Fluorescence OLEDs

In this study, two host materials, pCzBzbCz and pCzPybCz , are synthesized to achieve a high efficiency and long lifetime of blue thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs). The molecular design strategy involves the introduction of a pyridine group into the core structure of pCzPybCz as an electron-withdrawing unit, and an electron-donating phenyl group into the structure of pCzBzbCz . These host materials demonstrate good thermal stability and high triplet energy (T₁=3.07 eV for pCzBzbCz and 3.06 eV for pCzPybCz ) for the fabrication of blue TADF-OLEDs. In particular, pCzPybCz -based OLED devices demonstrate an external quantum efficiency (EQE) of 22.7 % and an operational lifetime of 24 h (LT₉₀, time to attain 90 % of initial luminance) at an initial luminance of 1000 cd m⁻². This superior lifetime could be explained by the C−N bond dissociation energy (BDE) in the host molecular structure. Furthermore, a mixed-host system using the electron-deficient 2,4-bis(dibenzo[b,d]furan-2-yl)-6-phenyl-1,3,5-triazine (DDBFT) is proposed to inhibit the formation of the anion state of our host materials. In short, the device operational lifetime is further improved by applying DDBFT. The carbazole-based asymmetric host molecule containing a pyridine core realizes a high-efficiency blue TADF-OLED showing a positive effect on the operating lifetime, and can provide useful strategies for designing new host materials.     

Highly Efficient Orange and Warm White Phosphorescent OLEDs Based on a Host Material with a Carbazole–Fluorenyl Hybrid

A new carbazole–fluorenyl hybrid compound, 3,3′(2,7‐di(naphthaline‐2‐yl)‐9H‐fluorene‐9,9‐diyl)bis(9‐phenyl‐9H‐carbazole) (NFBC) was synthesized and characterized. The compound exhibits blue‐violet emission both in solution and in film, with peaks centered at 404 and 420 nm. In addition to the application as a blue emitter, NFBC is demonstrated to be a good host for phosphorescent dopants. By doping Ir(2‐phq)₃ in NFBC, a highly efficient orange organic light‐emitting diode (OLED) with a maximum efficiency of 32 cd A^?1 (26.5 Lm W^?1) was obtained. Unlike most phosphorescent OLEDs, the device prepared in our study shows little efficiency roll‐off at high brightness and maintains current efficiencies of 31.9 and 26.8 cd A^?1 at a luminance of 1000 and 10 000 cd m^?2, respectively. By using NFBC simultaneously as a blue fluorescence emitter and as a host for a phosphorescent dopant, a warm white OLED with a maximum efficiency of 22.9 Lm W^?1 (21.9 cd A^?1) was also obtained.     

Using an Organic Molecule with Low Triplet Energy as a Host in a Highly Efficient Blue Electrophosphorescent Device

To achieve high efficiencies in blue phosphorescent organic light‐emitting diodes (PhOLEDs), the triplet energies (T₁) of host materials are generally supposed to be higher than the blue phosphors. A small organic molecule with low singlet energy (S₁) of 2.80 eV and triplet energy of 2.71 eV can be used as the host material for the blue phosphor, [bis(4,6‐difluorophenylpyridinato‐N,C^2′)iridium(III)] tetrakis(1‐pyrazolyl)borate (FIr6; T₁=2.73 eV). In both the photo‐ and electro‐excited processes, the energy transfer from the host material to FIr6 was found to be efficient. In a three organic‐layer device, the maximum current efficiency of 37 cd A^?1 and power efficiency of 40 Lm W^?1 were achieved for the FIr6‐based blue PhOLEDs.     

Phosphine Sulfide-Based Bipolar Host Materials for Blue Phosphorescent Organic Light-Emitting Diodes

Three phosphine sulfide-based bipolar host materials, viz CzPhPS, DCzPhPS, and TCzPhPS, were facilely prepared through a one-pot synthesis in excellent yields. The developed hosts exhibit superior thermal stabilities with the decomposition temperatures (T_d) all exceeding 350 °C and the melting temperatures (T_m) over 200 °C. In addition, their triplet energy (E_T) levels are estimated to be higher than 3.0 eV, illustrating that they are applicable to serve as hosts for blue phosphorescent organic light-emitting diodes (PhOLEDs). The maxima luminance, current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE) of 17,223 cd m⁻², 36.7 cd A⁻¹, 37.5 lm W⁻¹, and 17.5% are achieved for the blue PhOLEDs hosted by CzPhPS. The PhOLEDs based on DCzPhPS and TCzPhPS show inferior device performance than that of CzPhPS, which might be ascribed to the deteriorated charge transporting balance as the increased number of the constructed carbazole units in DCzPhPS and TCzPhPS molecules would enhance the hole-transporting ability of the devices to a large extent. Our study demonstrates that the bipolar hosts derived from phosphine sulfide have enormous potential applications in blue PhOLEDs, and the quantity of donors should be well controlled to exploit highly efficient phosphine sulfide-based hosts.     

一种苯并咪唑类双极性蓝色磷光主体材料的合成及性能

设计合成了一种基于苯并咪唑的新型双极性蓝色磷光主体材料1-苯基-2-[4-(N-咔唑基)苯基]苯并咪唑(PCPB),并对其结构进行了表征。通过紫外-可见、荧光、低温磷光光谱以及循环伏安法、热重分析、差热分析和密度泛函理论对其性能及结构进行了研究。结果表明,PCPB在CH2Cl2稀溶液中的吸收峰位于296和368 nm,发射峰位于401nm,属于深蓝色荧光;PCPB的低温(77K)磷光光谱的第一吸收峰位于452nm,其三线态能级为2.74e V,与蓝色磷光材料FIrpic(2.62e V)的能级相匹配;PCPB的HOMO主要分布在苯基咔唑单元,而LUMO主要定域在苯并咪唑环上。其HOMO能级为-5.54e V,与阳极ITO的功函(-4.5~-5.0 e V)相匹配,LUMO能级为-2.68e V,接近于电子传输材料PBD(-2.82e V)。PCPB表现出双极传导性能,且热稳定性良好。     

有机小分子室温磷光材料的研究进展

室温磷光不仅能直观地反映磷光发光体的激发态跃迁过程,而且在光电、传感、生物成像和信息加密等领域具有广阔的应用前景.因此,近年来室温磷光材料的研究引起了人们越来越多的兴趣与关注,成为发光材料、尤其是有机发光功能材料领域的一个新的研究热点.本综述总结了近年来关于有机小分子室温磷光材料的研究进展,主要围绕基于氢键的室温磷光材料、含有卤素的室温磷光材料、基于给体-受体(D-A)结构的室温磷光材料和具有圆偏振发光(CPL)性质的有机小分子室温磷光材料展开介绍.     

三嗪类双极性蓝色磷光主体材料的合成及性能

设计合成了一种基于三嗪类的新型双极性蓝色磷光主体材料[4-(4,6-二-α-萘氧基-1,3,5-三嗪-2-基)苯基]9-咔唑(NOTPC),并对其结构进行了表征。通过紫外-可见(UV-Vis)吸收、荧光、低温磷光、循环伏安法、热重分析(TGA)、差热分析(DSC)和密度泛函理论(DFT)对其性能及结构进行了研究。结果表明,NOTPC在CH₂Cl₂稀溶液中的吸收峰位于341和374 nm;发射峰位于478 nm;NOTPC的低温(77 K)磷光光谱的第一发射峰位于442 nm,其三线态能级为2.80 eV,与蓝色磷光材料FIrpic(2.62 eV)的能级相匹配;NOTPC的HOMO主要分布在苯基咔唑单元,而LUMO主要定域在三嗪环上。其HOMO能级为-5.40 eV,与阳极ITO的功函(-4.5~-5.0 eV)相匹配,LUMO能级为-2.32 eV,接近于电子传输材料PBD(-2.82 eV),NOTPC表现出双极传导性能, 且热稳定性良好。     

蓝色磷光有机发光材料

有机发光二极管在信息显示和固体照明领域具有广阔的应用前景,二十多年来得到了广泛关注,取得了很大进展。但显示和照明必需的蓝色发光材料,特别是蓝色磷光材料是目前有机发光材料研究领域的瓶颈,其稳定性和效率亟待提高。本文总结了近年来蓝色磷光有机发光材料的研究进展,系统介绍了蓝色磷光染料和主体材料这两大类材料的分子设计思想和发展动态,以及它们在有机发光二极管中的应用,并对蓝色磷光有机发光材料未来的研究方向进行了展望。     

晶态咔唑基有机室温磷光材料

自2008年咔唑的有机室温磷光(Organic Room-Temperature Phosphorescence, ORTP)被证实后,以咔唑单元构建ORTP材料成为一种行之有效的方法,并发展出一系列结构多样、性能优异、应用广泛、极具代表性的ORTP材料体系。本文首先总结了改善ORTP材料磷光性能的三种策略,即H-聚集体、重原子效应和给受体结构。在此基础上,系统梳理了晶态咔唑类有机室温磷光材料的研究进展,介绍了通过上述三种策略,抑制三重态松弛、增强自旋轨道耦合,以及减小单重态-三重态能级差、增强分子间电荷转移相互作用力,从而稳定三重激发态、增加系间窜越速率、促进磷光发射,最终实现长寿命高效率晶态咔唑类ORTP材料。最后,介绍了ORTP材料在防伪、信息安全和生物成像等领域的应用。