超支化聚对苯共聚物的合成及表征

利用Suzuki缩聚反应,合成了以1,3,6,8-(N-己基)咔唑为核的新型超支化聚对苯撑共聚物.用红外、核磁共振对聚合物的结构进行测定,表明咔唑以及吡啶单元成功引入聚合物中.聚合物可溶于四氢呋喃、氯仿和甲苯等有机溶剂.用凝胶渗透色谱法测得超支化聚合物的分子量在40000～110000之间,分子量随着1,3,6,8-(N-已基)咔唑含量的增加逐渐增加.超支化聚合物在溶液和薄膜状态下的吸收峰分别位于315～334nm和402～410nm之间.随着支化咔唑单元含量的增加,超支化聚合物的吸收峰均发生一定程度的蓝移.超支化聚合物在溶液和薄膜状态下的最大发射峰分别位于402～410nm和402～415nm之间,并且随着引入的支化咔唑单元含量的增加,分子内发生更加有效的分子内电荷转移,PL光谱发生略微的红移.     

聚芴类电致发光材料研究进展

聚芴及其衍生物是一类重要的聚合物蓝色电致发光材料.主要从均聚芴、共聚芴、以及C-9位引入螺环结构的聚芴等方面,介绍了聚芴类电致发光材料的研究进展.     

有机电致发光中的蓝光材料研究进展

发光材料是OLED器件中必不可缺少的材料,其中蓝光材料最为重要,因此受到了研究人员的广泛关注。介绍了有机小分子蓝光材料的研究和应用情况,综述了聚对苯(PPPs)、聚对苯撑乙烯(PPVs)、聚噻吩(PTs)和聚芴(PFs)等有机高分子蓝光材料的研究情况,并重点详细阐述了近年来国内外研究人员对不同类型的咔唑类高分子蓝光材料的研究进展,对咔唑类蓝光材料的研究方向进行了展望,指出了共聚类咔唑类高分子蓝光材料是最有潜力的蓝光材料发展方向。     

聚合物主体材料在磷光有机电致发光器件中的研究进展

综述了近几年用于磷光有机电致发光器件的聚合物主体材料的研究进展,着重介绍了聚咔唑类主体材料、聚芴类主体材料、聚苯乙烯类主体材料和聚间苯基类主体材料的结构单元的设计与修饰以及磷光器件性能的研究进展。同时,还展望了磷光聚合物主体材料的发展前景,提出了今后磷光聚合物主体材料的发展方向。     

羟乙基聚芴材料合成与表征

以2,7-二溴-9,9-二(2-羟乙基)-芴和2,7-双硼酸酯-(9,9-二辛基芴)为单体,通过Suzuki聚合反应合成一种蓝光聚(9,9-二羟乙基-2,7-芴)-2,7-(9,9-二辛基芴)(PFOH),采用1HNMR和热重分析对其进行表征,PFOH聚合物具有良好的热稳定性,通过紫外-可见吸收光谱(UV-vis)、光致发光光谱(PL)表征了聚合物的光物理性能,采用循环伏安法通过计算得知聚合物PFOH光学带隙Eg为2.90eV,EHOMO=-5.46eV,ELOMO=-2.56eV。     

磺酸型聚芴的合成及性能

利用迈克尔加成反应合成了2,7-二溴-9,9-二-(3-丙基酰胺-2-甲基丙磺酸)芴单体,并通过Suzuki偶合反应制备了含不同磺酸比例的磺酸型聚芴(PF6SO3H)。通过核磁共振氢谱、凝胶渗透色谱、溶解性试验、紫外吸收光谱、荧光发射光谱、循环伏安曲线及热重分析法对聚合物结构和性能进行了表征分析。结果表明,成功合成了相对分子质量在3万~5万之间的磺酸型聚芴。发现随着磺酸型聚芴中磺酸基团含量的不同,聚合物在甲醇溶液中的溶解度不同,含有50%磺酸基团的PF6SO3H在甲醇中的溶解度达到了18mg/mL。磺酸侧链的引入使聚芴在薄膜状态和溶液状态下的紫外吸收最大吸收峰和最大荧光发射峰较聚(9,9-二己基)芴(PF6)发生了9nm~40nm红移,且能带隙逐渐变窄,同时磺酸型聚芴的HOMO较PF6增大。热失重分析发现磺酸侧链的引入,使得磺酸型聚芴的热稳定性较PF6有一定的下降。     

基于芴和噻吩的共轭聚合物的固相合成及其表征

通过Stille偶合反应合成了2,7位二噻吩基取代的新型芴类衍生物并首次应用固相聚合法合成出聚-2,7-二噻吩基芴.在25℃测得聚合物的特性粘度为0.68dl/g.通过核磁共振(1H-NMR)、红外光谱(FTIR)对单体和聚合物的结构进行了表征确认,同时研究了聚合物的光学、结晶态形貌及热学性能.研究发现,2,7-二噻吩基芴在研磨过程中发生了聚合反应且其偶合发生在e,e′位置.     

一种超支化共轭聚合物的合成与2,4-二硝基甲苯的荧光猝灭

以2,4,6-三甲基均三嗪和甲酰基咔唑、二甲酰基咔唑为原料,通过羟醛缩合反应合成了化合物I及超支化荧光共轭聚合物II,其中I可以视为II的组成单体。聚合物II在常见有机溶剂中有较好的溶解度,其X射线衍射谱图中2θ=24.2°的位置有1个较宽的峰;其吸收和荧光光谱与I的相比仅有轻微红移(3nm),这些结果都说明聚合物II分子间没有紧密的π-π堆积作用。聚合物II的荧光强度是化合物I的2倍。2,4-二硝基甲苯对其荧光猝灭研究结果表明,超支化聚合物II具有比化合物I更大的荧光猝灭常数(Ksv=95.52L/mol),表现出了一定的分子导线效应。     

高效窄带隙共轭聚合物太阳能电池材料设计及器件性能研究进展

窄带隙聚合物材料因能与太阳光谱更好地匹配而备受重视,是聚合物太阳能电池的研究热点。按照窄带隙聚合物给体单元的结构分类,总结了含芴、硅芴、咔唑、环戊二烯并双噻吩、三苯胺和吩噻嗪给体单元的太阳能电池材料的设计以及器件性能,介绍了聚合物的HOMO和LUMO能隙值对其光谱和光电转换效率的影响,并指出了该研究领域目前存在的问题及今后的发展方向。     

发光波长可调的聚吡咯甲烷的制备及光学特性

聚合物发光材料因其拥有诸多优点,在有机发光二极管器件方面的应用前景广阔.然而,对于蓝光聚合物发光材料,由于其发光性能、使用寿命等方面仍然存在不足,难以满足全色显示的需要.以吡咯类单体和4-乙基苯甲醛单体为原料,采用溶液缩聚法制备了3种聚吡咯甲烷(聚{吡咯-[2,5-二(4-乙基苯甲烷)]}(PPE)、聚{N-甲基吡咯-...     

Efficient color tuning (blue, red-orange, white) of light emitting diodes by excitation energy transfer

We present a color tuning technique allowing to control the emission colors of polymer light emitting diodes (PLEDS), which is of considerable interest for flat panel display applications. The emission color variation of the PLED from blue to red-orange is achieved by blending small amounts of a red light emitting guest polymer with the active PLED layer consisting of a blue emitting laddertype poly (paraphenylene) (LPPP). Using this new technique we realized highly efficient stable single layer PLEDs emitting different colors including white light emission. Besides the color tuning, which is established by an efficient excitation energy transfer (EET) and charge transfer from the host, m-LPPP, to the guest polymer, a significant increase of the photoluminescence (PL) and the electroluminescence (EL) quantum efficiency is observed.     

Role of Au nanoparticles in efficiency enhancement and green band emission quenching of blue polymer light emitting diodes

We studied photoluminescence (PL) and electroluminescence (EL) properties of polymer light emitting diodes (PLEDs) constructed with polyconjugated polymers blends containing Au nanoparticles (DA-Au NPs; 5.3 nm +/- 1.1 nm in diameter) capped by dodecylamine. For the blue light emitting polyfluorene polymers, selective quenching of excimer peaks or so-called green bands was observed in PL as well as in EL when they were mixed with small amounts (1-4 wt%) of DA-Au NP. The influence of DA-Au NPs on the light-emitting characteristics of the PLEDs strongly depended on the nature of the matrix polymer, which was particularly conspicuous for the polymers whose emission wavelength matches or overlaps with the surface plasmon resonance wavelength region of Au nanoparticles. Especially, the purity of the blue color emitted by the poly [2,7-(9,9-di-n-dioctylfluorene) (PF) was greatly improved by Au NPs that suppressed the 'green band.' All the PLEDs doped with DA-Au NPs showed enhanced maximum external quantum efficiency and emitted light intensity when compared to undoped counterparts.     

Photo and electroluminescence of a platinum porphyrin doping of complexes with two metal cores

In this paper, four new complexes with two metal cores [2Sm, 2Sn, 2Zn and 2Pb] were prepared and utilized as host material in in the electroluminescence (EL) devices. Devices with two metal cores and with the structure of ITO/PEDOT: PSS (60 nm)/PVK (55 nm)/[2Sm, 2Sn, 2Zn and 2Pb]: %8 [2,5PtTPP] (45 nm)/Al (200 nm) were fabricated, A blue–green photoluminescence (PL) emission with a blue shift compared to the 2,5PtTPP was observed. 2,5PtTPP doped in 2Sm and 2Sn showed more pure red color compared to 2Zn and 2Pb based devices. We believe that energy transfer occurring at 2,5PtTPP/[2Sm, 2Sn] molecules is responsible for the red color in the EL of the device. The electronic effect of two metal cores of complexes influenced the maximum current density, brightness, and luminous efficiency of the devices. Finally, we have demonstrated the samarium complex of 8-hydroxyquinoline is a promising host material for red OLEDs with high efficiency and has a simple device structure.     

Synthesis and electroluminescence properties of novel silicon-based copolymers containing oxadiazole and fluorene units for PLED

Novel silicon-based copolymers containing an electron-deficient oxadiazole unit and a fluorine unit have been successfully synthesized through the Heck reaction. They are soluble in common organic solvents such as THF, CHCl₃, etc. Their UV–visible absorption spectra exhibit a strong maximum band at the range of 355–381 nm in thin film. Upon a photoexcitation of 350 nm, their photoluminescence spectra show a strong maximum band around 455–475 nm in thin film. The multi-layered light-emitting diodes (LEDs) of Al(200 nm)/Ca(50 nm)/EL polymer(80 nm)/PEDOT(50 nm)/ITO were fabricated. J–V curves show the turn-on voltage in the range of 4.4–7 V. These LEDs emit the white emissive color, due to the combination of a blue electroluminescent (EL) color and a red EL color arising from the formation of a certain charge complex.     

Synthesis of Carbon Dots with Multiple Color Emission by Controlled Graphitization and Surface Functionalization

Multiple‐color‐emissive carbon dots (CDots) have potential applications in various fields such as bioimaging, light‐emitting devices, and photocatalysis. The majority of the current CDots to date exhibit excitation‐wavelength‐dependent emissions with their maximum emission limited at the blue‐light region. Here, a synthesis of multiple‐color‐emission CDots by controlled graphitization and surface function is reported. The CDots are synthesized through controlled thermal pyrolysis of citric acid and urea. By regulating the thermal‐pyrolysis temperature and ratio of reactants, the maximum emission of the resulting CDots gradually shifts from blue to red light, covering the entire light spectrum. Specifically, the emission position of the CDots can be tuned from 430 to 630 nm through controlling the extent of graphitization and the amount of surface functional groups, ? COOH. The relative photoluminescence quantum yields of the CDots with blue, green, and red emission reach up to 52.6%, 35.1%, and 12.9%, respectively. Furthermore, it is demonstrated that the CDots can be uniformly dispersed into epoxy resins and be fabricated as transparent CDots/epoxy composites for multiple‐color‐ and white‐light‐emitting devices. This research opens a door for developing low‐cost CDots as alternative phosphors for light‐emitting devices.     

Synthesis and characterization of highly twisted and bulky tetraoctyloxybiphenyl-containing polyfluorene copolymers: toward efficient blue polymer light emitting diodes

We have synthesized new blue light emitting random copolymers, poly(9,9'-n-dioctylfluorene-co-2,2',6,6'-tetraoctyloxybiphenyl-3,3'-diyl)s (PFTOBPs), via Ni(0)-mediated coupling reactions. The PL emission peaks of the resulting copolymers closely resembled those of the polyfluorene (PF) homopolymer. The EL devices fabricated using these copolymers exhibited highly pure blue emission with approximate 1931 CIE coordinates of (0.15, 0.15) at 1000 cd/m2. The maximum brightnesses ranged from 2000 to 12000 cd/m2 with maximum efficiencies from 0.53 to 0.97 cd/A. The efficiencies were found to increase as the fraction of TOBP in the copolymers was increased, which may result the inhibition of exciton quenching that is produced by the introduction of the highly twisted and bulky TOBP moieties into the copolymers.     

Electroluminescence of fluorescent–phosphorescent organic light-emitting diodes with regular,inverted, and symmetrical structures

The influence of the device structure on the electroluminescence (EL) properties of fluorescent–phosphorescent organic light emitting diodes (OLEDs) was demonstrated. Four devices with regular-, inverted-, compensated- and symmetrical-emission layers (EMLs) were prepared. In regular-EML device, DCJTB emission increased when the phosphorescent sensitized EML was thickened. In inverted-EML device, low electron energy barrier at the Bphen/BCzVB interface resulted in weakened blue emission. The compensated-EML device, prepared with a red color-compensated layer, showed a color-tunable broadband white emission. Conversely, device with a quantum-like symmetrical-EML showed a narrow color-temperature range. Stable EL efficiency was obtained from regular, compensated, and symmetrical-EML devices. In contrast, EL efficiency of inverted-EML device rolled off significantly, though it had the highest EL efficiency of 11.4 cd/A.     

电压调节变色的有机薄膜电致发光器件

制备了结构为ＩＴＯ／ＳＡ／ＰＢＤ／Ａｌｑ３／Ａｌ的电压调制发光颜色的有机薄膜电致发光器件，研究了有机层厚度不同的器件的发光光谱随电压变化的性能，建立了器件的能级结构模型，并用这种模型解释了器件的电致发光性能。     

Large‐Scale Horizontally Aligned ZnO Microrod Arrays with Controlled Orientation,Periodic Distribution as Building Blocks for Chip‐in Piezo‐Phototronic LEDs

A novel method of fabricating large‐scale horizontally aligned ZnO microrod arrays with controlled orientation and periodic distribution via combing technology is introduced. Horizontally aligned ZnO microrod arrays with uniform orientation and periodic distribution can be realized based on the conventional bottom‐up method prepared vertically aligned ZnO microrod matrix via the combing method. When the combing parameters are changed, the orientation of horizontally aligned ZnO microrod arrays can be adjusted (θ = 90° or 45°) in a plane and a misalignment angle of the microrods (0.3° to 2.3°) with low‐growth density can be obtained. To explore the potential applications based on the vertically and horizontally aligned ZnO microrods on p‐GaN layer, piezo‐phototronic devices such as heterojunction LEDs are built. Electroluminescence (EL) emission patterns can be adjusted for the vertically and horizontally aligned ZnO microrods/p‐GaN heterojunction LEDs by applying forward bias. Moreover, the emission color from UV‐blue to yellow‐green can be tuned by investigating the piezoelectric properties of the materials. The EL emission mechanisms of the LEDs are discussed in terms of band diagrams of the heterojunctions and carrier recombination processes.     

Efficient Vacuum‐Processed Light‐Emitting Diodes Based on Carbene–Metal–Amides

Efficient vacuum‐processed organic light‐emitting diodes are fabricated using a carbene–metal–amide material, CMA1. An electroluminescence (EL) external quantum efficiency of 23% is achieved in a host‐free emissive layer comprising pure CMA1. Furthermore external quantum efficiencies of up to 26.9% are achieved in host–guest emissive layers. EL spectra are found to depend on both the emissive‐layer doping concentration and the choice of host material, enabling tuning of emission color from mid‐green (Commission Internationale de l'Éclairage co‐ordinates [0.24, 0.46]) to sky blue ([0.22 0.35]) without changing dopant. This tuning is achieved without compromising luminescence efficiency (>80%) while maintaining a short radiative lifetime of triplets (<1 μs).