蓝色磷光材料Flrpic的发光特性

研究了掺杂浓度及热退火对磷光材料双(4,6-二氟苯基吡啶-N,C2’)吡啶甲酰合铱(Flrpic)发光性能的影响.不同掺杂浓度的薄膜及有机电致发光器件(OELDs)的发光颜色部随Flrpic浓度的增大由蓝色逐渐变化到黄绿色.纯Flrpic薄膜的吸收光谱和光致发光(PL)光谱在440-480 nm范围内有明显的光谱重叠,476 nm处的发光强度随Flrpic掺杂浓度增大而降低主要是由自吸收效应引起的.测量了不同激发密度下的光致发光光谱和不同掺杂浓度下的电致发光(EL)光谱,发现530 nm处的发光强度随激发强度或掺杂浓度的增大而增强,证实了530 nm处的发光是来源于Flrpic分子间的激基缔合物发光.通过比较热退火前后薄膜微观形貌及电致发光器件光谱的变化,进一步证实了热退火促进Flrpic分子聚集,增强了Flrpic分子间的辐射跃迁发光.通过调控Flrpic掺杂浓度和优化器件结构,并对器件进行热退火处理得到一系列发光颜色从蓝色逐渐变化到黄绿色的有机电致发光器件.     

一种新型苯乙烯衍生物的光致发光与电致发光

对一种新型苯乙烯衍生物的光致发光和电致发光进行了研究。１－９－蒽基－４－氯甲基－２,５－二甲氧基苯的溶液随浓度的增大,其单体荧光逐渐减弱而激基复合物发光逐渐增强。在薄膜状态只有激基复合物荧光,表明在溶液和薄膜状态下均存在单体向激基复合物的能量转移过程,用分子间距离越近,能量转移效率越高。以该化合物制成的单层二极管器件,其电致发光光谱随电压增强从激基复合物发光逐渐转变为激复合发光。     

PVK与新型D-π-A分子掺杂体系的能量转移及发光性质

通过对PVK与4种新型D-π-A分子(分别简写为CKD, TKD, PKD, NKD)掺杂体系的吸收光谱、激发光谱和光致发光光谱的研究, 分析了掺杂体系的光致发光特性和能量转移现象. 制备了结构为ITO/PEDOT/PVK∶D-π-A ω/Alq3/Al的电致发光器件, 研究了掺杂体系的电致发光性能. 研究结果表明, 通过改变D-π-A分子中不同给电子能力的电子给体, 可以调控其带隙, 进而实现对D-π-A分子发光峰位的调节; 给电子基团空间立构效应越高, 其荧光量子效率越高. 在掺杂体系的光致发光和电致发光中, PVK与D-π-A分子之间都发生了有效的能量转移, 通过调节PVK与D-π-A分子的比例, 可以调节掺杂体系的发光性能. 当TKD在PVK中的掺杂质量分数为6％时, 电致发光器件发光亮度为729.1 cd/m2时, 发光效率达到1.75 cd/A.     

主链为咔唑-吖啶给体/侧基为三联吡啶受体的热诱导延迟荧光共轭聚合物合成及发光性质

成膜性能优异的聚合物发光材料适宜于可溶液加工大尺寸显示及照明器件制作,赋予其热诱导延迟荧光(TADF)特征能够有效改善器件发光性能.本工作以苯环对位桥连三联吡啶的吖啶衍生物(ABTPy)为TADF单体、咔唑(Cz)衍生物为共聚单体,利用交叉偶联反应,控制TADF单体摩尔投料比为1%、5%、10%和50%,合成了4个主链为咔唑-吖啶给体/侧基为三联吡啶受体的共轭聚合物PCzABTPy1～PCzABTPy50.低含量TADF单元聚合物溶液的光致发光光谱显示了低聚咔唑片段和TADF单元的双峰发射,发光峰位是420和488 nm,聚合物薄膜仅出现单峰发射,发光峰由470 nm红移至508 nm.聚合物瞬态荧光衰减光谱均包含纳秒级瞬时荧光(12～15 ns)和微秒级延迟荧光(1.3～4.8μs),证实聚合物具有TADF特性.以聚合物为发光层的非掺杂溶液加工电致发光器件实现了蓝光发射,发光波长位于452～484 nm.其中,PCzABTPy10发光器件展示了最优的发光性能,最大外量子效率(EQE)为9.4%,启亮电压为3.0 eV.在亮度1000 cd/m²时,器件EQE仍保...     

芴-呋喃苯并噻二唑共聚物的光电性能

对芴-呋喃苯并噻二唑共聚物的吸收光谱、光致发光光谱、电致发光性能和光伏性能进行了研究. 共聚物在382 nm和530 nm处有两处明显的吸收峰, 其中530 nm处的吸收强度随着共聚物中呋喃苯并噻二唑单元(FBT)含量的增加而增加. 随着FBT单元含量的增加, 电致发光峰值从611 nm红移至702 nm. 以PVK为空穴传输层, 共聚物PFO- FBT0.1为发光层的发光器件, 在33 mA/cm2电流密度下的外量子效率达2.32%, 亮度为441 cd/m2. 实验中观察到快速的链内能量陷阱过程(从芴到FBT单元). 以共聚物PFO-FBT50为电子给体、PCBM为电子受体(重量比1:2)共混制备的光电池能量转换效率为1.13%, 开路电压0.85 V, 短路电流3.39 mA/cm2, 光谱响应边延伸至近750 nm.     

超薄层在白色有机电致发光器件中的应用

以DCJTB为掺杂剂, 以BCP为空穴阻挡层, 研究了两种结构的有机电致发光器件ITO/NPB/BCP/Alq3:DCJTB/Alq3/Al(结构A)和ITO/NPB/BCP/Alq3/Alq3:DCJTB/Alq3/Al(结构B)的电致发光光谱. 实验结果显示, 在结构A器件的电致发光光谱中, 绿光的相对发光强度较弱,增加Alq3层的厚度对绿光的相对发光强度的影响也很小; 而在结构B器件的电致发光光谱中, BCP层与掺杂层(Alq3:DCJTB)之间的Alq3薄层对绿光的相对发光强度影响显著, 用很薄的Alq3层就可以得到强的绿光发射. 进一步改变器件结构, 利用有机超薄层就可以得到稳定的白光器件ITO/NPB(50 nm)/BCP(3 nm)/Alq3(3 nm)/Alq3:DCJTB(1%(w))(5 nm)/Alq3(7 nm)/Al. 随着电压的增加(14-18 V), 该器件的色坐标基本保持在(0.33, 0.37)处不动; 在432 mA·cm-2的电流密度下, 该器件的发光亮度可达11521 cd·m-2.     

退火温度对PLD法制备ZnO:Eu3+,Li+薄膜结构和发光性质的影响

采用脉冲激光沉积(PLD)法在Si(111)衬底上制备了Eu3+,Li+共掺杂的ZnO薄膜,分别在450,500,550和600℃条件下进行退火,退火气氛为真空。利用X射线衍射(XRD)仪和荧光分光光度计研究了退火温度对薄膜结构和光致发光(PL)的影响。研究结果表明,Eu3+,Li+共掺杂的ZnO薄膜具有c轴择优取向,Eu3+,Li+没有单独形成结晶的氧化物,均以离子形式掺入ZnO晶格中。PL谱中有较宽的ZnO基质缺陷发光,ZnO基质与稀土Eu3+之间存在能量传递,但没有有效的能量传递。随着退火温度的增加,薄膜发光先增强后减弱,退火温度为550℃时发光最强。当用395 nm的激发光激发样品时,仅观察到稀土Eu3+在594 nm附近的特征发光峰,但发光强度随退火温度变化不明显。     

一种环金属铱、铂双核配合物的合成及光电性能

设计合成了一种双核环金属铱,铂配合物二[N,N-2-(2,4-二氟苯基吡啶)C3,N1](吡啶甲酸)合铱(Ⅲ)-C₆-[苯基吡啶-C3,N1](吡啶甲酸)合铂(Ⅱ)(FIrPPyPt)。 通过核磁共振仪、元素分析仪、紫外-可见吸收光谱仪和光致发光光谱仪对其结构和性能进行了表征。 结果表明,配合物FIrPPyPt的紫外-可见吸收位于250~450 nm之间,荧光发射峰位于465和493 nm。 将配合物FIrPPyPt以质量分数1%~8%掺杂到主体材料聚乙烯基咔唑(PVK)+2-(联苯-4-芳基)-5-(4-叔丁基苯)-1,3,4-噁二唑(PBD)(30%)中制作了电致发光器件,在不同电压下电致发光光谱中,显现出铱配合物和铂配合物的特征峰,波峰位于400、500和530 nm蓝绿光区发射区。 该双核配合物用于单掺杂有机白光电致发光器件具有制作简单、色稳定性和重复性好等特点,为单掺杂白光发光器件提供了一种好的思路。     

ZnS:Tm的薄膜电致发光及激发过程

用电子束蒸发的方法制备了传统的双绝缘层的ZnS:Tm的薄膜电致发光器件，对其电致发光谱进行分析，在光致发光中，Tm离子受到基质ZnS的无辐射能量传递，而在电致发光中，Tm被过热电子碰撞激发而非能量传递，在所研制的电致发光器件中，稀土TmF3掺杂浓度不同，器件的发光性能也不同，在双绝缘层的ZnS:Tm的薄膜电致发光器件的基础上，改变器件的结构，发现器件的蓝光发射与红光发射之比增加，并对Tm离子可能的发光机理进行了探讨。     

基于联咔唑为骨架的双极主体材料的合成及其在有机电致发光器件中的应用

咔唑类衍生物具有良好的空穴传输性能和较高的三重态能级,在有机电致发光器件中一般用来构建空穴传输材料和主体材料。本文通过在联咔唑的3和6位引入具有电子传输能力的氰基,设计合成了一种以双咔唑二聚体为分子骨架的新型双极性有机电致发光主体材料6,6’-双氰基-9,9’-二苯基-3,3’-联咔唑（BCzDCN）,研究了其发光性能、热稳定性和电化学性质。低温磷光发射光谱测试表明BCzDCN的三重态能级高于传统的天蓝色磷光掺杂材料双（4,6-二氟苯基吡啶-N,C²’）吡啶甲酰合铱（FIrpic）。以BCzDCN为主体材料,FIrpic和双（4-苯并噻吩）[3,2-C]吡啶-N,C²’）乙酰丙酮合铱（PO-01）分别为蓝色和黄色磷光掺杂材料,制备了蓝色和白色有机磷光发光二极管器件。器件的最大电流效率分别达到34.6 cd/A和59.0 cd/A。并且在1000 cd/m²亮度下的效率滚降仅有4.1%和5.1%。     

吡啶-芴类电荧光聚合物的光谱特性

用Suzuiki聚合反应将二溴代吡啶 (2 ,5 、2 ,6 、3,5 取代 )与芴共聚 ,合成了不同主链结构的吡啶 芴共聚物 .研究结果表明 ,将吡啶基引人聚芴主链可以调节共聚物的发光颜色 .间位吡啶基引入聚芴主链 ,使聚合物的能级加宽 ,PL、EL光谱发生蓝移 ;对位吡啶基则使光谱红移 .间位吡啶基 (3,5 Py、2 ,6 Py)引入聚芴主链 ,可提高聚合物的色纯度 .共聚物中 3,5 Py含量为 4 0mol%时 ,可得到较纯的蓝光 .     

White light emission from single layer poly (n-vinylcarbazole) polymeric light-emitting devices by mixing singlet and triplet excimer emissions

White light electroluminescence (EL) was obtained by mixing emission from singlet and triplet excimers from a single poly (n-vinylcarbazole) (PVK) spin cast layer after irradiation of the solution with UV light. With increased UV light irradiation, the intensity from the triplet excimer (red-630 nm) of PVK increased compared with that of the singlet excimer (blue-460 nm) due to an increased population of both adjacent benzene rings being aligned with one another (fully overlapping) versus only one of the adjacent benzene rings being aligned (partially overlapping). The emission color changed from blue to white with increased UV irradiation time while the EL brightness and current density decreased and the turn-on voltage increased.     

Effect of Al-doping on the structure and optical properties of electrospun zinc oxide nanofiber films

Electrospun ZnO precursor nanofibers of average diameters 122±64 nm, 117±44 nm and 110±39 nm were fabricated by controlling the Al concentration of a polymeric solution. The resulting nanofibers were characterized by the XRD, SEM, EDS, TEM, XPS and PL. The electrospun Al-doped ZnO nanofiber films were polycrystalline and composed of densely packed grains, with crystallite size ranging from 28.7 nm, 25.7 nm, 25.4 nm to 20.4 nm corresponding to the atomic concentration of aluminum from 0, 1.6, 2.5 to 5.8 at.%. The incorporation of aluminum resulted in a decrease trend in the grain size and lattice parameter of the ZnO nanofiber films. The room temperature PL spectra of all samples show three different emissions, including UV (ultraviolet) emission with an obvious blue shift, Vis (visible) emission and NIR (near infrared) emission, the intensity of which decreases monotonically as the doping concentration is increased except for the highest doping level. The impurity content correlates with changes in the PL spectra, and the appropriate Al doping can improve the optical properties of ZnO nanofibers. The small size effect and Al-doping or the impurity incorporation should be responsible for the blue shift observation in Al-doped ZnO nanofiber films.     

Spiro-bridged ladder-type poly(p-phenylene)s: towards structurally perfect light-emitting materials

Structurally perfect spiro-bridged ladder-type poly(p-phenylene)s, which show blue fluorescence in the photoluminescence (PL) and electroluminescence (EL) emission spectra, are prepared by Suzuki-Miyaura polycondensation and Friedel-Crafts cyclization. The polymers are free of ketonic defects, exhibiting excellent thermal and color stability upon annealing in air at 110 degrees C for 24 h.     

Electroplex emission from a blend of poly(N-vinylcarbazole) and 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline

The PL and EL spectra of poly(N-vinylcarbazole) (PVK) : 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline (BCP) (1:1 w/w) film were found completely different. The PL spectrum is a single peak at 415 nm that originates from excitons emission from PVK, and the tail of the spectrum is suggested to be excimer emission from BCP molecules. However, a new emission at 595 nm was found in the EL spectra of devices ITO/PEDOT:PSS(50 nm)/PVK:BCP(1:1)(100 nm)/Al. After aggregate, exciplex and product of electrochemical reaction were ruled out, the new emission was proposed to be electroplex emission that occurred between PVK and BCP molecules. Under high voltage, only electroplex emission can be observed in the EL spectra.     

溶胶-凝胶法制备掺Sm3+的SiO2玻璃的结构及发光性能

利用溶胶-凝胶技术制备了掺不同量Sm3+和不同退火温度下的SiO2凝胶和玻璃,通过三维荧光光谱、激发光谱、发射光谱的测试,确定了Sm3+在SiO2凝胶玻璃中的最佳激发波长为360 nm,最强发射波长为610 nm,激发光谱的峰位置在360、393、464 nm处,发射光谱的峰位置在578、591、595、610、732nm处,分别归属于4G5/2-6H5/2、4G5/2-6H7/2、4G5/2-6H11/2跃迁,并证明当掺杂量达到1.15%时,Sm3+的发光最强,当Sm3+的掺杂量超过1.15%时,发生浓度猝灭效应.     

Preparation and spectral characteristics of anthracene/tetracene mixed crystals

A series of tetracene-doped anthracene crystals with different doping concentrations (the highest molar ratio 100 1) are grown from solution. Crystal structures and optical characteristics of the above mixed crystals are investigated at room temperature. By changing the doping concentrations, the fluorescence can be adjusted from blue-green to green and even to yellow-green. The emission spectra of anthracene/tetracene (An/Te) mixed crystals reveal the sensitized fluorescence of tetracene and the partial quenching of anthracene emission. The data of transient photoluminescence (PL) decays illustrate that in An/Te mixed crystals, the decay of anthracene becomes faster, while the PL lifetime of tetracene is longer than that of the tetracene single crystals. All above experimental results suggest that there is excitation energy transfer from anthracene to tetracene in the mixed crystals. Supported by the National Natural Science Foundation of China (Grant No. 5057 3039) and the National Key Basic Research and Development Program of China (Grant No. 2006CB806200)     

Synthesis and characterization of novel blue emitting Na2CaSiO4:Ce3+ phosphor

The blue phosphors Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ were synthesized by the sol–gel method and their luminescence characteristics were investigated for the first time. Structural information about prepared samples is obtained by analyzing the XRD patterns and SEM micrographs. The photoluminescence (PL) excitation spectra indicate that the Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ phosphors can be effectively excited by ultraviolet (360 nm) light. The PL emission spectra exhibit tunable blue broadband emission with the dominant wavelength of 427–447 nm under excitation of 360 nm by controlling the doping concentration of Ce³⁺. The concentration quenching effect for Ce³⁺ was found at the optimum doping concentration of 4 mol%. The Commission Internationale de l’Eclairage 1931 chromaticity coordinates of Na_1.96Ca_0.96SiO₄:0.04Ce³⁺ are (0.1447, 0.0787), which are better color purity compared to the commercial Eu²⁺-doped BaMgAl₁₀O₁₇ phosphor. Na_1.96Ca_0.96SiO₄:0.04Ce³⁺ composition shows intense blue emission (peak wavelength, 439 nm) with relative intensity versus commercial BaMgAl₁₀O₁₇:Eu²⁺ blue phosphor (Nichia) 65 and 158 % under 254 and 365 nm excitation, respectively. All the results indicate that Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ phosphors are potential candidate as a blue emitting phosphor for UV-converting white light-emitting diodes.     

Synthesis and optoelectronic properties of alternating benzofuran/terfluorene copolymer with stable blue emission

The solution processable alternating benzofuran/terfluorene copolymer bearing side oxadiazole groups ( PBF‐OXD ) was synthesized and its optoelectronic properties and color stability were investigated. Electron‐deficient and stereohindered oxadiazole units were used as pendent groups to compensate for the poor electron‐transporting ability of a p‐type polymer backbone, to depress the intermolecular π‐stacking, and to improve solubility while retaining polymer blue emission. PBF‐OXD showed a glass transition at 135 °C and an onset decomposition temperature of ～345 °C. A simple EL device, with the configuration of ITO/PEDOT:PSS/ PBF‐OXD /Ba/Al, displayed a stable blue emission (λ_max = 434 nm), good color purity (full width half‐maximum = 59 nm), maximum brightness of 1400 cd/m², and a maximum luminance efficiency of 0.95 cd/A. The PL and EL spectra changed slightly on annealing and on increasing the applied voltage. These results show that the as‐synthesized copolymer PBF‐OXD had integrated respective functions of its different building blocks and exhibited good thermal and color stability with improved EL performance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5488–5497, 2009     

Iridium complex grafted to 3,6‐carbazole‐alt‐tetraphenylsilane copolymers for blue electrophosphorescence

We designed a 3,6‐dibromo‐9‐hexyl‐9H‐carbazole derivative with the blue emissive iridium complex bis[2‐(4,6‐difluorophenyl)pyridyl‐N,C^2′](picolinato)iridium(III) (FIrpic) linked at the alkyl terminal. Based on this monomer, novel 3,6‐carbazole‐alt‐tetraphenylsilane copolymers grafted with FIrpic were synthesized by palladium‐catalyzed Suzuki coupling reaction, and the content of FIrpic in the polymers could be controlled by feed ratio of the monomers. The polymer films mainly show blue emission from FIrpic, and the emission intensity from the polymer backbones is much weaker compared with the doped analogues, which demonstrates an efficient energy transfer from polymeric host to covalently bonded guest. The phase separation in the polymers was suppressed, which can be identified by atomic force microscopy and designed electroluminescent (EL) devices. EL devices based on the polymers exhibited blue phosphorescence from FIrpic. The luminous efficiency of preliminary devices reached 2.3 cd/A, and the efficiency roll‐off at high current densities was suppressed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1859–1865, 2010