梯形茚并芴基红绿蓝三色聚合物激光增益材料的设计合成与性能

采用Suzuki聚合方法合成了一类梯形茚并芴基共轭聚合物,其中梯形茚并芴单元分别与蒽(An)、苯并噻二唑(BT)以及双噻吩基苯并噻二唑(TBT)进行交替共聚,得到了蓝(2LF-An)、绿(2LF-BT)、红(2LF-TBT)三色发光的共轭聚合物材料,薄膜状态下,发射波长分别为448、545、632 nm,发射光谱覆盖可见光波段.制备的有机电致发光器件获得了三基色电致发光:2LF-An、2LF-BT、2LF-TBT器件的电流效率分别为1.10、3.11、0.50 cd/A,最大亮度分别为2772、8582、1682 cd/m~2.自发放大辐射(ASE)测试结果显示,2LF-An和2LFBT获得了较低ASE泵浦阈值(Eth),分别为20.90和65.84μJ/cm~2,增益分别为62.40和66.07 cm~(-1),而常见的聚(9,9-二辛基芴-苯并噻二唑)衍生物(F8BT)在相同测试条件下的增益仅为26.88 cm-1.2LF-TBT红光聚合物材料通过掺杂后观察到ASE行为,当掺杂比例为1%时,Eth为88.04μJ/cm~2,增益g为68 cm~(-1).更重要的是,ASE稳定性测试结果表明,所得红绿蓝三色聚合物材料均表现出优异的ASE发光稳定性,即使在200oC退火处理的条件下仍能维持ASE泵浦阈值不发生明显变化.优异的光稳定性和高增益特性使得该类梯形茚并芴基共轭聚合物展现出作为激光增益介质的应用潜力.     

聚芴主链含D-A型萘并噻二唑和苯并硒二唑衍生物的红光高分子发光材料

设计合成了新型的含萘并噻二唑（NT）或苯并硒二唑（BS）电子受体单元的D-A型红光掺杂剂,将它们引入到聚芴(PFO)的主链,调节掺杂剂含量,合成了一系列具有“掺杂剂/主体”特性的红光高分子材料含萘并噻二唑衍生物的聚芴(PFR-xNT)和含苯并硒二唑衍生物的取芴(PFR-xBS)。 这些红光高分子的吸收光谱主要表现为聚芴主体的吸收,荧光光谱既有主体聚芴的蓝光峰,也有掺杂剂的红光峰,并且红光峰的相对强度随着掺杂剂含量的增加而增强。 与光致发光光谱不同,这些高分子的电致发光光谱主要表现为掺杂剂的红光发射,并在掺杂的摩尔分数达到1%时实现了主体聚芴向红光掺杂剂的完全能量转移。 其中PFR-10NT和PFR-10BS的单层器件(ITO/PEDOT:PSS/Polymer/Ca/Al)(PEDOT:聚3,4-乙烯二氧噻吩;PSS:聚苯乙烯磺酸)分别实现了电流效率1.61 cd/A,最大发射波长632 nm,CIE色坐标（0.63,0.35）以及电流效率1.10 cd/A,最大发射波长620 nm,CIE色坐标（0.63,0.36）的高效红光发射。     

侧链接枝低聚对亚苯基亚乙烯基聚芴衍生物的合成及其电致发光性能

采用Wittig-Horner反应,将少量端基为磷脂的黄光发射客体低聚对亚苯基亚乙烯基链段(MOPV)接枝到含有醛基单体的蓝光发射主体材料聚芴的侧链上,合成了一种新型的接枝聚芴衍生物PF-g-MOPV.这种接枝聚合物具有很好的热稳定性,可溶于常用的有机溶剂.以接枝共聚物PF-g-MOPV为发光层的单层器件发射出黄绿光,色坐标为(0.30,0.57),最大发光亮度达到1550cm/m2,这说明蓝光聚芴主链向侧链MOPV进行了有效地能量转移.     

聚芴类蓝光材料抑制链簇集及绿光发射的新进展

在共轭聚合物研究领域,聚芴是一类非常有前途的蓝光材料,针对其分子链易簇集及发光过程中易产生绿光等问题,本文对最近三年以来聚芴类发光材料的研究进展进行了综述.     

基于荧光共轭聚合物的金属离子传感研究

设计合成了一系列结构相似的共轭主链含5%苯并噻二唑结构单元及侧链带胺类金属离子螯合基团的阴离子型水溶性共轭聚合物PFA, PFBTA和PFBTNA, 并对它们在不同极性溶剂中的光物理性质进行了研究. 利用分子主链含适量苯并噻二唑共聚单元的聚芴衍生物聚集态不同荧光光谱及颜色发生显著变化这一特性, 研究了这一系列水溶性聚芴衍生物在水/甲醇(9/1)溶液中对金属离子的荧光响应过程. 结果表明, 金属离子不仅能通过能量及电荷转移猝灭聚合物荧光, 还可以通过静电相互作用力使聚合物聚集态发生改变, 进而影响聚合物的光学性质. 同时分子链上引入金属离子螯合基团能够显著提高体系的检测灵敏度, 聚合物PFBTA和PFBTNA可以特异性识别Cu²⁺离子, 并且可做为其它金属离子的广谱型比色法检测材料.     

芴类蓝光生色团在合成有机电致发光材料中的应用

有机电致发光技术在通信、信息、显示和照明等领域显现出巨大的商业应用前景, 十几年来一直是光电信息领域的研究热点之一。相对于无机电致发光材料,有机电致发光材料具有许多优点。芴作为一种具有刚性平面联苯结构的化合物,由于具有宽的能隙、高的发光效率和结构上易于修饰等特点,已成为一类受到各方关注的蓝光生色团。因此,芴类蓝光生色团在合成高效稳定电致蓝光材料、聚芴β相结构的调整、多功能化、主体材料、白光材料、有机激光及有机纳米发光材料等方面得到了广泛的应用。本文从材料合成的角度综述了芴类蓝光生色团在合成有机电致发光材料方面所取得的最新研究进展,讨论了芴类蓝光生色团在上述领域应用过程中所存在的问题和功能拓展方向,并对下一步需要研究的热点问题做了展望。     

绿色单峰发光聚(9,9-二烯丙基芴)的合成及其发光机制

为了得到绿色单峰发光的聚合物材料, 我们设计并合成了9位取代的二烯丙基芴单体, 在NiCl₂的催化下, 合成了可溶的聚芴衍生物, 聚(9,9-二烯丙基芴)(PAF). 较短的烯丙基链既可以增加聚芴的溶解度, 双键的存在又有利于聚芴发生分子间聚集而得到绿光发射的有机电致发光器件(OLED). PAF在溶液和薄膜状态下的荧光峰分别位于403和456 nm的蓝光区域, 而其器件ITO/PEDOT:PSS/PAF/LiF/Al(其中, ITO为氧化铟锡, PEDOT为聚(3,4-乙撑二氧噻吩), PSS为聚苯乙烯磺酸盐)的电致发光峰却红移至绿光区域(532 nm), 得到绿色单峰发光. 紫外吸收光谱、荧光发射光谱、红外光谱以及原子力显微镜(AFM)图像的结果证明, 造成PAF电致发绿光的机制为聚合物分子间聚集.     

聚芴类电致发光材料*

聚芴与其衍生物是一类重要的电致发光聚合物,它们具有较高的光致发光效率,并且易于进行结构修饰,因此受到材料化学家们的高度关注。本文叙述的线索是聚合物结构与其电致发光性能之间的构效关系。通过化学修饰,可以调节材料的前线分子轨道、热和光谱稳定性,进而开发新的发光材料。文中首先简单介绍了聚芴类发光材料的聚合方法,然后把这些聚合物按结构不同分成两个部分介绍：一部分是主链仅含有共轭芴单元的聚合物,它们的化学修饰依赖于芴9位的活性碳原子;另一部分是通过共聚方法得到的主链含有芴和其它基团的聚合物。     

一种新型激光材料──高分子激光材料研究的最新进展

激光(Laser)是通过辐射的受激发射进行光放大的简称,它是六十年代发展起来的一门新兴技术,其应用几乎遍及所有的科技领域。通常的激光器由激光介质(激光材料)、激发(泵浦)系统和光学谐振腔组成^[1]。激光介质是激光器的核心部分,它是用来实现粒子数反转和产生光的受激发射的物质,目前使用的激光工作物质通常为固体(晶体、玻璃等)、气体(原子气体、离子气体、分子气体)、半导体、液体(有机和无机液体)等。这些材料通常制作工艺难度大,价格昂贵并且在性能上有各自的局限性。长期以来,科学家们一直致力于发展新型激光材料以期获得更完美的激光器^[2～6]。     

含联芴烯单元共轭聚合物的合成及表征

以六羰基钨[W(CO)₆]为催化剂, 合成了聚吲哚芴(P1)、 聚梯型四苯(P2)、 聚梯型五苯(P3)和小分子9-联吲哚芴烯(S1).该类聚合物的重复单元含有联芴烯结构, 通过芴9位的双键连接. 光学和电化学等实验结果表明, 聚合物无荧光发射, 是一类窄带隙的共轭聚合物, 其中聚合物P1薄膜的紫外吸收值最大波长为710 nm.     

Energy transfer mediated fluorescence from blended conjugated polymer nanoparticles

Nanoparticles consisting of a derivative of the blue-emitting conjugated polymer polyfluorene doped with green-, yellow-, and red-emitting conjugated polymers were prepared by a reprecipitation method. The nanoparticles can be described as a system of densely packed chromophores that exhibit efficient energy transfer from the host to the dopant polymers. Fluorescence quenching analysis of the host polymer as a function of the dopant concentration indicates that one energy acceptor molecule can effectively quench 90% of the fluorescence of a nanoparticle consisting of 100-200 host conjugated polymer molecules. A nanoparticle energy transfer model was developed that successfully describes the quenching behavior of a small number of highly efficient energy acceptors per nanoparticle. The fluorescence brightness of the blended polymer nanoparticles was determined to be much higher than that of inorganic quantum dots and dye-loaded silica particles of similar dimensions. The combination of high fluorescence brightness and tunable fluorescence of these blended nanoparticles is promising for ultrasensitive fluorescence-based assays.     

Designing of the white-light emission from a single-polymer system: Quantum theoretical study

Quantum-chemical calculations are applied to study the white-light emission from a single-polymer system with simultaneous blue (polyfluorene as a blue host) and orange (2,1,3-benzothiadiazole-based derivative as an orange dopant) emissions. Particular attention is paid to the variation in electronic and optical properties upon the structure tuning in pristine 2,1,3-benzothiadiazole-based derivative. Importantly, by the introduction of electron-donating groups on terminal N,N-disubstituted amino groups, the electronic and optical properties of designed 2,1,3-benzothiadiazole-based derivative have been tuned, making them to be potential candidates as orange dopants in white organic light-emitting devices based on polymers with polyfluorene as a blue-light-emitting host. Furthermore, designed 2,1,3-benzothiadiazole-based derivatives have a possibility to be good hole or ambipolar transport materials in organic light-emitting diodes from the charge hopping model. Finally, we find that the designed 2,1,3-benzothiadiazole-based derivative exhibit improved stability.     

White electroluminescent single‐polymer achieved by incorporating three polyfluorene blue arms into a star‐shaped orange core

A series of star‐like dopant/host single‐polymer systems with a D‐A type star‐shaped orange core and three blue polyfluorene arms were designed and synthesized. Through tuning the doping concentration of the orange core and thermal annealing treatment of white polymer light‐emitting diodes based on them, highly efficient white electroluminescence has been achieved. A typical single‐layer device (ITO/PEDOT:PSS/polymer/Ca/Al) realized pure white emission with a luminous efficiency of 16.62 cd A^?1, an external quantum efficiency of 6.28% and CIE coordinates of (0.33, 0.36) for S‐WP‐002TPB3 containing 0.02 mol % orange core. The high efficiency of the devices could be mainly attributed to the suppressed concentration quenching of the dopant units, more efficient energy transfer from polymer host to orange dopant and thermal annealing‐induced α‐phase polyfluorene (PF) self‐dopant in amorphous PF host. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Efficient upconversion fluorescence in a blue-emitting spirobifluorene-anthracene copolymer doped with low concentrations of Pt(II)octaethylporphyrin

Upconversion-induced fluorescence in platinum-octaethylporphyrin (PtOEP)-doped thin films of a spirobifluorene-anthracene copolymer has been investigated. Upon exciting in the range of the absorption band (2.31 eV, 537 nm) of the guest molecules, blue fluorescence (2.75 eV, 450 nm) from the spirobifluorene host was observed. The intensity of the upconverted emission was found to be one order of magnitude higher than from a PtOEP doped but anthracene-free spirobifluorene copolymer and than previously reported for metallated porphyrin-doped polyfluorene samples. It is argued that the efficient upconversion originates from the triplet energy transfer from the phosphorescent dopant to the sensitive unit of the host polymer, followed by triplet-triplet annihilation and finally blue emission from the spirobifluorene host polymer backbone.     

Theoretical investigation on the white-light emission from a single-polymer system with simultaneous blue and orange emission (Part II)

We report here a theoretical investigation of the white-light emission from a single-polymer system with simultaneous blue (polyfluorene as a blue host) and orange (2,1,3-benzothiadiazole(BTD)-based derivative as an orange dopant) emission. With use of quantum-chemical approaches, our studies are focused on the variation in electronic and optical properties as a function of the chemical composition of the backbone in BTD-based derivatives. Furthermore, the results show that the electronic and optical properties of designed BTD-based derivatives can be tuned by the introduction of suitable electron-donating groups on terminal N,N-disubstituted amino groups, implying good candidates as orange dopants in WPLEDs with polyfluorene as a blue-light-emitting host. In addition, low reorganization energy values of holes or narrow differences between hole and electron transportations within the framework of the charge hopping model suggest designed BTD-based derivatives to be good hole transport or ambipolar transport materials in organic light-emitting diodes. It is also found that the designed BTD-based derivatives containing fluorene-based unit exhibit higher stability.     

Polyfluorene presenting dipolar pendent groups and its application to electroluminescent devices

We have synthesized a blue-light-emitting polyfluorene derivative (PF-TPAOXD) that presents sterically hindered, dipolar pendent groups functionalized at the C-9 positions of alternating fluorene units. The incorporation of the dipolar side chains, each comprising an electron-rich triphenylamine group and an electron-deficient oxadiazole group connected through a π-conjugated bridge, endows the resultant polymer with higher highest occupied molecular orbital and lower lowest unoccupied molecular orbital energy levels, which, consequently, lead to an increase in both hole and electron affinities. An electroluminescent device incorporating this polymer as the emitting layer exhibited a stable blue emission with a maximum brightness of 2080 cd/m² at 12 V and a maximum external quantum efficiency of 1.4% at a brightness of 137 cd/m². Furthermore, atomic force microscopy measurements indicated that the dipolar nature of PF-TPAOXD, in contrast to the general nonpolarity of polydialkylfluorenes, provided a stabilizing environment allowing the polar organometallic triplet dopant to be dispersed homogeneously. We also fabricated an electrophosphorescent device incorporating PF-TPAOXD as the host material doped with a red-emitting osmium complex to realize red electroluminescence with Commission Internationale de l'Eclairage color coordinates of (0.66, 0.34). The resulting device exhibited a maximum external quantum efficiency of 7.3% at a brightness of 1747 cd/m² and a maximum brightness of 7244 cd/m². © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2073–2084, 2007     

Low‐Threshold Non‐Doped Deep Blue Lasing from Monodisperse Truxene‐Cored Conjugated Starbursts with High Photostability

Herein, the photophysical, morphological, optical gain characteristics of a set of trigonal monodisperse starburst conjugated macromolecules ( Tr1‐Tr4 ) have been systematically investigated in order to elucidate the influence of the molecular structures on their optoelectronic performance. With increasing the oligofluorene arm length, absorption spectra were red‐shifted progressively, whereas an increase in photoluminescence quantum yields (PLQYs) and optical gain coefficients, and a corresponding reduction in amplified spontaneous emission (ASE) thresholds and loss coefficients were observed for Tr1‐Tr3 except for Tr4 . The results indicate that the effective conjugation length become saturated for Tr3 in this system. Impressively, the resulting molecules manifested very low ASE thresholds (4.4–11.6 μJ cm^?2) with high photostability, as well as high thermal stability. One dimensional distributed feedback (DFB) lasers exhibited a minimum lasing threshold of 10.38 nJ pulse^?1 (0.86 kW cm^?2, 4.325 μJ cm^?2) for Tr3 . It should be emphasized that the ASE threshold of Tr1‐Tr4 was nearly unchanged from room temperature to 200 °C. The results suggest that this kind of truxene‐cored conjugated starbursts with high photostability and low lasing thresholds are rather promising gain media for organic semiconductor lasers.     

Pure blue electroluminescent poly(aryl ether)s with dopant–host systems

A series of novel arylene ether polymers (P5F‐BCzVFs) containing both pentafluorene (5F) and distyrylarylene derivative (BCzVF) units in the side chains for efficient pure blue light emission were prepared by a facile, metal‐free condensation polymerization. The emission spectra indicated that color tuning could be achieved through efficient Förster energy transfer from the deep‐blue 5F host to the pure‐blue BCzVF dopant. Single‐layer polymer light‐emitting diodes (PLEDs) based on P5F‐BCzVFs (ITO/(PEDOT:PSS)/polymer/Ca/Al) exhibited voltage‐independent and stable pure blue emission with a Commission International de L'Eclairage (CIE) coordinate of (0.15, 0.15), a maximum brightness of 3576 cd/m², and a maximum luminous efficiencies of 2.15 cd/A, respectively. As most polymers with dopant‐host systems, the luminous efficiencies of all P5F‐BCzVFs surpassed that of the host‐only polymer (P5F), due to the energy transfer and charge trapping from the host to the dopant. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Donor–Acceptor Type Pendant Conjugated Molecules Based on a Triazine Center with Depressed Intramolecular Charge Transfer Characteristics as Gain Media for Organic Semiconductor Lasers

A set of fluorene-capped pendant conjugated molecules ( T-m and T-p ), which consist of a triazine center with three carbazole substituents as the donor–acceptor (D-A) type pendant structure, were designed, synthesized, and investigated as gain media for organic semiconductor lasers (OSLs). In particular, varying the capping positions of the fluorene units on the pendant core structures results in significantly different intramolecular charge transfer (ICT) properties, where T-m manifested depressed ICT characteristic and high fluorescence quantum yield. The lowest amplified spontaneous emission (ASE) threshold in neat films was recorded as 1.9 μJ cm⁻² for T-m and 83.8 μJ cm⁻² for T-p , which indicated that the depressed ICT characteristics in the case of T-m help to enhance the ASE properties. Remarkably, the ASE threshold remained almost unchanged and the ASE spectra showed very small shifts (within 1 nm) for T-m with film samples annealed up to 180 °C in open air. In contrast, its linear counterpart 2FEtCz-m showed a clearly increased ASE threshold upon annealing above 100 °C. The results suggest that the selective construction of conjugated pendant molecules with depressed ICT characteristics is beneficial for finely modulating the optical and electrical properties as well as improving the thermostability and photostability, which manifests the great potential as a robust gain media for OSLs.     

Fluorene‐based rib waveguides with optimized geometry for long‐term amplified spontaneous emission stability

Amongst the different optoelectronic applications of conjugated polymers, waveguide amplifiers and optically pumped lasers are those requiring larger photochemical stability, owing to the large irradiation conditions under operation. In this context, suitable waveguide optimization enabling the reduction of amplified spontaneous emission (ASE) threshold values appears as important as synthetic chemistry protocols to promote polymer robustness against photo‐oxidation. In this work, we develop rib waveguides with different geometries based on four different fluorene‐based compounds and assess the influence of rib confinement on ASE properties. We observe ASE threshold values as low as 8.9 × 10^?4 mJ cm^?2, being among the lowest threshold values reported so far on blue emitting polymer/oligomer waveguides. We demonstrate that the enhanced ASE efficiency on some of these rib waveguides leads to a fivefold increase in operation lifetime respect to spin‐coated slab waveguides, thus confirming the impact of waveguide geometry on ASE operation stability. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1040–1045