多芳胺取代均三嗪的合成及其光电性能的研究

设计合成了一个新的带有三支链的均三嗪衍生物分子: 2,4,6-三[4-(N,N-二对甲苯基)-苯胺乙基]均三嗪(TBTN); 用1H NMR, 13C NMR, IR, MS (MALDI-TOF)和元素分析确认了化合物的结构. 研究了该化合物的紫外吸收光谱、荧光光谱、电致发光光谱等性能, 用TBTN组装发光器件, 实验结果显示TBTN为发光层时, 该器件能发出稳定白光. 器件结构为ITO/2-TNATA (30 nm)/NPB (20 nm)/TBTN (30 nm)/Alq3 (30 nm)/LiF (0.5 nm)/Al, 在电压为15 V获得最大亮度是1523 cd/m2, 在驱动电压范围内CIE(国际照明委员会)坐标稳定并在白色等能区内.     

Characteristics of a single‐layered organic electroluminescent device using a carrier‐transporting copolymer and a nonconjugated light‐emitting polymer

We have synthesized a novel carrier‐transporting copolymer and a nonconjugated light‐emitting polymer. The carrier‐transporting copolymer has a triphenylamine moiety as a hole‐transporting unit and a triazine moiety as an electron‐transporting unit, both of which are located in the polymer side chain. The nonconjugated light‐emitting polymer has a perylene moiety, which acts as an emitting unit in the polymer side chain. These polymers are very soluble in most organic solvents, such as monochlorobenzene, tetrahydrofuran, chloroform, and benzene. A single‐layered electroluminescent device consisting of ITO/copolymer and emitting‐material 4‐(dicyanomethylene)‐2‐methyl‐6‐(4‐dimethylaminostyryl)‐4H‐pyran (DCM) or light‐emitting polymer)/Al mixtures exhibits maximum external quantum efficiency when the concentration of the emitting material is 30 wt %. The device emits red or blue light according to the emitting material. When CsF is used as the electron‐injecting material, the drive voltage decreases drastically to 7 V, and the highest quantum efficiency is 0.5%. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2733–2743, 2003     

聚芳烃二乙炔类共轭高分子的合成及其发光性质的研究

通过Glaser-Hay氧化偶联反应合成含有咔唑与对烷氧基苯结构单元的聚芳烃二乙炔。利用核磁共振、红外光谱、凝胶渗透色谱、紫外光谱、电致发光光谱、热重分析等测试手段表征其结构,测定相对分子质量及其分布,并研究光学、热学和电化学方面的性能。并将这种聚合物作为器件的发光层,其器件结构为ITO/PEDOT/Polymer/Ba/Al,结果表明起亮电压为6.5V,其外量子效率达到0.21%,最大亮度达到90 cd/m2。     

含萘噁二唑铍配合物的合成及光致发光和电致发光性能研究

合成了含有萘环的二唑铍配合物并对其进行了表征.在紫外光的激发下配合物能够发出很强的蓝色荧光.采用NPB为空穴传输层、配合物为发光层制备了双层器件,得到了蓝色的电致发光,证明该配合物是一种良好的电致发光材料.     

DFT/TDDFT Studies on the Electronic Structures and Spectral Properties of Carbazole‐based Blue Light‐emitting Dendrimers

The purpose of this paper is to provide an in‐depth investigation of the electronic and optical properties of two series of carbazole‐based blue light‐emitting dendrimers, including 1 – 6 six oligomers. These materials show great potential for application in organic light‐emitting diodes as efficient blue‐light and red‐light emitting materials due to the tuning of the optical and electronic properties by the use of different electron donors (D) and electron acceptors (A). The geometric and electronic structures of these compounds in the ground state are calculated using density functional theory (DFT) and the ab initio HF, whereas the lowest singlet excited states were optimized by ab initio single excitation configuration interaction (CIS). All DFT calculations are performed using the B3LYP functional on 6‐31G* basis set. The outcomes show that the highest occupied molecular orbitals (HOMOs), lowest occupied molecular orbitals (LUMOs), energies gaps, ionization potentials, electron affinities and reorganization energies of each molecular are affected by different D and A moieties and different substitute positions.     

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

Higher efficiency in the end‐use of energy requires substantial progress in lighting concepts. All the technologies under development are based on solid‐state electroluminescent materials and belong to the general area of solid‐state lighting (SSL). The two main technologies being developed in SSL are light‐emitting diodes (LEDs) and organic light‐emitting diodes (OLEDs), but in recent years, light‐emitting electrochemical cells (LECs) have emerged as an alternative option. The luminescent materials in LECs are either luminescent polymers together with ionic salts or ionic species, such as ionic transition‐metal complexes (iTMCs). Cyclometalated complexes of Ir^III are by far the most utilized class of iTMCs in LECs. Herein, we show how these complexes can be prepared and discuss their unique electronic, photophysical, and photochemical properties. Finally, the progress in the performance of iTMCs based LECs, in terms of turn‐on time, stability, efficiency, and color is presented.     

Deep‐Red to Near‐Infrared Thermally Activated Delayed Fluorescence in Organic Solid Films and Electroluminescent Devices

The design and synthesis of highly efficient deep red (DR) and near‐infrared (NIR) organic emitting materials with characteristic of thermally activated delayed fluorescence (TADF) still remains a great challenge. A strategy was developed to construct TADF organic solid films with strong DR or NIR emission feature. The triphenylamine (TPA) and quinoxaline‐6,7‐dicarbonitrile (QCN) were employed as electron donor (D) and acceptor (A), respectively, to synthesize a TADF compound, TPA‐QCN. The TPA‐QCN molecule with orange‐red emission in solution was employed as a dopant to prepare DR and NIR luminescent solid thin films. The high doped concentration and neat films exhibited efficient DR and NIR emissions, respectively. The highly efficient DR and NIR organic light‐emitting devices (OLEDs) were fabricated by regulating TPA‐QCN dopant concentration in the emitting layers.     

A Novel Greenish Blue‐emitting Amorphous Molecular Material: 2,5‐Bis {4‐[2‐naphthyl (phenyl) amino ] phenyl} thiophene

A novel greenish blue‐emitting amorphous molecular material, 2,5‐bis{4‐[2‐naphthyl(phenyl)amino]phenyl thiophene (BN‐pA‐1T), was designed and synthesized. Its molecular properties, glass‐forming property, and application to an organic EL device were investigated.     

Synthesis of new polyfluorene copolymers with a comonomer containing triphenylamine units and their applications in white‐light‐emitting diodes

Novel conjugated polyfluorene copolymers, poly[9,9‐dihexylfluorene‐2,7‐diyl‐co‐(2,5‐bis(4′‐diphenylaminostyryl)‐phenylene‐1,4‐diyl)]s (PGs), have been synthesized by nickel(0)‐mediated polymerization from 2,7‐dibromo‐9,9‐dihexylfluorene and 1,4′‐dibromo‐2,5‐bis(4‐diphenylaminostyryl)benzene with various molar ratios of the monomers. Because of the incorporation of triphenylamine (TPA) moieties, PGs exhibit much higher HOMO levels than the corresponding polyfluorene homopolymers and are able to facilitate hole injection into the polymer layer from the anode electrode in light‐emitting diodes. Conventional polymeric light‐emitting devices with the configuration ITO/PEDOT:PSS/polymer/Ca/Al have been fabricated. A light‐emitting device produced with one of the PG copolymers (PG10) as the emitting layer exhibited a voltage‐independent and stable bluish‐green emission with color coordinates of (0.22, 0.42) at 5 V. The maximum brightness and current efficiency of the PG10 device were 3370 cd/m² (at 9.6 V) and 0.6 cd/A, respectively. To realize a white polymeric light‐emitting diode, PG10 as the host material was blended with 1.0 wt % of a red‐light‐emitting polymer, poly[9,9‐dioctylfluorene‐2,7‐diyl‐alt‐2,5‐bis(2‐thienyl‐2‐cyanovinyl)‐1‐(2′‐ethylhexyloxy)‐4‐methoxybenzene‐5′,5′‐diyl] (PFR4‐S), and poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV). The device based on PG10:PFR4‐S showed an almost perfect pure white electroluminescence emission, with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.36) at 8 V; for the PG10:MEH‐PPV device, the CIE coordinates at this voltage were (0.30, 0.40) with a maximum brightness of 1930 cd/m². Moreover, the white‐light emission from the PG10:PFR4‐S device was stable even at different driving voltages and had CIE coordinates of (0.34, 0.36) at 6 V and (0.31, 0.35) at 10 V. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1199–1209, 2007     

Existence of a new emitting singlet state of proflavine: femtosecond dynamics of the excited state processes and quantum chemical studies in different solvents

Proflavine (3,6-diaminoacridine) shows fluorescence emission with lifetime, 4.6 ± 0.2 ns, in all the solvents irrespective of the solvent polarity. To understand this unusual photophysical property, investigations were carried out using steady state and time-resolved fluorescence spectroscopy in the pico- and femtosecond time domain. Molecular geometries in the ground and low-lying excited states of proflavine were examined by complete structural optimization using ab initio quantum chemical computations at HF/6-311++G** and CIS/6-311++G** levels. Time dependent density functional theory (TDDFT) calculations were performed to study the excitation energies in the low-lying excited states. The steady state absorption and emission spectral details of proflavine are found to be influenced by solvents. The femtosecond fluorescence decay of the proflavine in all the solvents follows triexponential function with two ultrafast decay components (τ(1) and τ(2)) in addition to the nanosecond component. The ultrafast decay component, τ(1), is attributed to the solvation dynamics of the particular solvent used. The second ultrafast decay component, τ(2), is found to vary from 50 to 215 ps depending upon the solvent. The amplitudes of the ultrafast decay components vary with the wavelength and show time dependent spectral shift in the emission maximum. The observation is interpreted that the time dependent spectral shift is not only due to solvation dynamics but also due to the existence of more than one emitting state of proflavine in the solvent used. Time resolved area normalized emission spectral (TRANES) analysis shows an isoemissive point, indicating the presence of two emitting states in homogeneous solution. Detailed femtosecond fluorescence decay analysis allows us to isolate the two independent emitting components of the close lying singlet states. The CIS and TDDFT calculations also support the existence of the close lying emitting states. The near constant lifetime observed for proflavine in different solvents is suggested to be due to the similar dipole moments of the ground and the evolved emitting singlet state of the dye from the Franck-Condon excited state.     

High red,green, and blue color purity electroluminescence from MEH‐PPV and polyalkyfluorenes‐based bright white polymer light emitting displays

A series of white polymer light emitting displays (PLEDs) based on a polymer blend of polyalkylfluorenes and poly(2‐methoxy‐5,2′‐ethyl‐hexyloxy‐1,4‐phenylene vinylene) (MEH‐PPV) was developed. MEH‐PPV or red light emitting alkyfluorene copolymer (PFR) was blended with blue light emitting alkyfluorene copolymer (PFB), and MEH‐PPV was blended with both green light emitting alkyfluorene copolymer (PFG) and PFB to generate white light emission PLEDs. Low turn on voltage (2.7 V), high brightness (12,149 nits), high efficiency (4.0 cd/A, 4.0 lm/W), and good color purity (Commission Internationale de L'Eclairage (CIE_x,y) co‐ordinates (0.32, 0.34)) were obtained for the white PLEDs based on the PFB and MEH‐PPV polymer blend. Exciplex formation in the interface between PFR and PFB induced a new green emission peak for these two components based white PLEDs. As a result, strong white emission (4078 nits) was obtained by mixing the red, green, and blue (RGB) three primary colors. High color purity of blue (CIE, x = 0.14, y = 0.08), green (CIE, x = 0.32, y = 0.64) and red (CIE, x = 0.67, y = 0.33) emissions was achieved for white PLEDs combining with dielectric interference color‐filters. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 330–341, 2007     

Long-lived near-infrared luminescent lanthanide complexes of imidodiphosphinate "shell" ligands

Near-infrared emitting complexes of Nd(III), Er(III), and Yb(III) based on hexacoordinate lanthanide ions with an aryl functionalized imidodiphosphinate ligand, tpip, have been synthesized and fully characterized. Three tpip ligands form a shell around the lanthanide with the ligand coordinating via the two oxygens leading to neutral complexes, Ln(tpip)3. In the X-ray crystal structures of Er(III) and Nd(III) complexes there is evidence of CH-pi interactions between the phenyl groups. Photophysical investigations of solution samples of the complexes demonstrate that all complexes exhibit relatively long luminescence lifetimes in nondeuteurated solvents. Luminescence studies of powder samples have also been recorded for examination of the properties of NIR complexes in the solid state for potential material applications. The results underline the effective shielding of the lanthanide by the twelve phenyl groups of the tpip ligands and the reduction of high-energy vibrations in close proximity to the lanthanide, both features important in the design of NIR emitting lanthanide complexes.     

Organic electroluminescent device based on electropolymerized polybithiophene as the hole-transport layer

An ultrathin film of polybithiophene (PBTh), used in organic electroluminescent (EL) devices, was generated by an electrochemical method with a conducting indium tin oxide (ITO) glass as the working electrode. The light-emitting layer could be deposited directly onto the PBTh by using spin coating for fabrication of the organic EL devices. It was found that the film of PBTh as the hole-transport layer for the EL device could effectively raise the EL intensity and efficiency. The EL intensity of the ITO/PBTh/emitting layer/Al device is about 100 times as strong as that of the ITO/emitting layer/Al device at the same current density of 50 mA/cm².     

In situ access to white light‐emitting fluorescent polymer nanocomposites via plasma‐ignited frontal polymerization

We describe a facile fabrication of white light‐emitting cadmium sulfide (CdS)‐poly(HEA‐co‐NVK) nanocomposites [2‐hydroxyethyl acrylate (HEA) and N‐vinylcarbazole (NVK)] via plasma‐ignited frontal polymerization (PIFP), a novel and rapid reaction mode of converting monomers into polymers in minutes. Frontal polymerization was initiated by igniting the upper side of the reactant with plasma. Once initiated, no additional energy was required for the polymerization to occur. The chemical functional groups of the as‐prepared nanocomposites were thoroughly investigated using Fourier transform infrared spectra. The dependence of the front velocity and front temperature on the initiator concentration and weight ratios of HEA/NVK was also investigated in detail. Perhaps more interestingly, the white light‐emitting materials synthesized by ingeniously incorporating the compensating colors of yellow emitting from 3‐(trimethoxysilyl)‐1‐propanethiol‐capped CdS nanocrystals and blue emitting from carbazole‐containing polymer were conveniently applied onto a commercial UV light‐emitting diode (LED) to generate white LEDs. The subtle change in the weight ratios of CdS/NVK can significantly impact the color hue. The white light becomes gradually colder with the increase of NVK, but becomes gradually warmer with the increase concentration of CdS nanocrystals. In a broad perspective, these white light‐emitting materials designed by PIFP approach will open a new pathway to develop “QD‐polymer nanocomposite down‐conversion LED” in a fast and efficient way. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Study of the double-pulse setup with an orthogonal beam geometry for laser-induced breakdown spectroscopy

Single- and double-pulse laser-induced breakdown spectroscopy (LIBS) was applied on aluminum samples at atmospheric pressure in air. In the case of the double-pulse scheme, experiments were carried out with an ablation laser emitting at 532 nm and a reheating laser emitting at 1064 nm in an orthogonal beam geometry. With the use of a 1-m focal length monochromator and an echelle spectrometer both equipped with an intensified charge coupled device (ICCD), the studies on the effect of the delay between the two laser pulses displayed optimum enhancements of line emissions only at 200 ns in the reheating scheme developed here. The experimental parameters, like the signal acquisition delay, were largely studied. The line intensity enhancements were also investigated in dependence on physical parameters, such as the excitation energy levels of the lines observed. Moreover, the relative importance of ionic and neutral lines in the emission spectra was precisely characterized. From the different investigations, the behaviors of the line emissions towards the double-pulse technique were related to their excitation energy levels. A correlation between the increases in intensity and the excitation energy levels of the line emissions was highlighted. As a result, the reheating scheme showed improvements of sensitivity for elements emitting ionic lines compared with the corresponding single-pulse experiments.     

Judicious Choice of N‐Heterocycles for the Realization of Sky‐Blue‐ to Green‐Emitting Carbazolylgold(III) C^C^N Complexes and Their Applications for Organic Light‐Emitting Devices

A new class of sky‐blue‐ to green‐emitting carbazolylgold(III) C^C^N complexes containing pyrazole or benzimidazole moieties has been successfully designed and synthesized. Through the judicious choice of the N‐heterocycles in the cyclometalating ligand and the tailor‐made carbazole moieties, maximum photoluminescence quantum yields of 0.52 and 0.39 have been realized in the green‐ and sky‐blue‐emitting complexes, respectively. Solution‐processed and vacuum‐deposited organic light‐emitting devices (OLEDs) based on the benzimidazole‐containing complexes have been prepared. The sky‐blue‐emitting device shows an emission peaking at 484 nm with a narrow full‐width at half‐maximum of 57 nm (2244 cm^?1), demonstrating the potential of this class of complexes in the application of OLEDs with high color purity. In addition, high maximum external quantum efficiencies of 12.3 % and a long operational half‐lifetime of over 5300 h at 100 cd m^?2 have been achieved in the vacuum‐deposited green‐emitting devices.     

Proper Choice of XC Functionals and Calculations of Fluorescence-Emitting Energies for Coumarin Derivatives

A scheme of time-dependent density functional theory (TDDFT) combined with single-excitation configuration interaction (CIS) approach was employed to make a detailed investigation of the emitting energy for fifteen well-known coumarin derivatives. The results showed that the predicted emitting energies as well as the absorption ones were dominated mainly by the exchange-correlation (XC) functional to be used. So long as a functional is properly chosen, the experimental emitting energy of most derivatives can be accurately reproduced within 0.16 eV by a calculation at the TDDFT/6-31G(d)//CIS/3-21G(d) theoretical level. It was found that, nevertheless, the hybrid functional, B3LYP, well predicted the absorption energies for all the fifteen coumarin derivatives but none of the functionals could work equally well for the emitting energy calculations. Two pure functionals, OLYP and BLYP, yield good emitting energies for the 7-aminocoumarins or derivatives with a N atom connected to 7-position, which exhibit inconspicuous charge transfer (CT) in their excited states, whereas the B3LYP hybrid functional, with 20% Hartree-Fock (HF) exchange energy, performs significantly better than OLYP and BLYP for those 3-substituted coumarins with larger CT in excited states. Thus, in comparison with the absorption energies, the selection of proper functionals for the emitting energy calculations becomes more complex. In all probability, it is effective and doable to choose an XC-functional with alterable fraction of HF exchange energy according to the composition and structure characteristics of molecule.     

三重态发光材料Cu4掺杂的PVK发光器件及特殊的发光增强机理研究

多种有机发光材料已被应用于电致发光（EL）器件的制备,其荧光效率远比无机发光材料高。与光激发直接产生单重态洋鬼子不同,电致发光过程是电子空穴分别由相反极性的电极注入（非成对电子注入）,三重态和单重态激子同时生成,按自旋统计理论预测,三重态和单重态子的比例为3：1。由于三重态的跃迁是自旋禁阻的,大部分有机分子的三重态激子发光效率极低,有机电致发光器件的最高交率限制在25％（对于光致发光效率100％的理想情况）。为进一步提高器件效率,人们开始设想和实施对通常认为是无效激发的75％的三重激发态进行利用,其关键是筛选出适于器件应用的高效率三重态发光材料,据此我们选择过渡金属配合物Cu4(C≡CPh4)4L2[L=1,8-bis9diphenyl phosphino)-3,6-dioxaoctane]（以下简称Cu4）进行了器件性能研究。     

Red–Green–Blue Trichromophoric Nanoparticles with Dual Fluorescence Resonance Energy Transfer: Highly Sensitive Fluorogenic Response Toward Polyanions

A red–green–blue (RGB) trichromophoric fluorescent organic nanoparticle exhibiting multi‐colour emission was constructed; the blue‐emitting cationic oligofluorene nanoparticle acted as an energy‐donor scaffold to undergo fluorescence resonance energy transfer (FRET) to a red‐emitting dye embedded in the nanoparticle (interior FRET) and to a green‐emitting dye adsorbed on the surface through electrostatic interactions (exterior FRET). Each FRET event occurs independently and is free from sequential FRET, thus the resultant dual‐FRET system exhibits multi‐colour emission, including white, in aqueous solution and film state. A characteristic white‐emissive nanoparticle showed visible responses upon perturbation of the exterior FRET efficiency by acceptor displacement, leading to highly sensitive responses toward polyanions in a ratiometric manner. Specifically, our system exhibits high sensitivity toward heparin with an extremely low detection limit.     

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.