基于中性红染料的新型红色发光材料

以具有生物染色作用的中性红染料为主结构,设计合成了两个新型中性红衍生物2-(N-邻苯二甲酰亚胺)-3-甲基-8-二甲胺吩嗪(NRDl)和N,N'-二(3-甲基-8二甲胺-2-吩嗪)-1,4,5,8-萘二酰亚胺(NRD2).实验制作了结构为ITO/NPB(43 nm)/Alq3:dopant(20 nm)/Alq3(32 nm)/Lif(1 nm)/Al(120 nm)的发光器件,在掺杂质量百分比浓度分别为1.0%、2.3%和4.1%时,NRDl的发光峰值分别为582 nm、588 nm和594 nm,在电压为12 V时,发光亮度达到5552cd·m-2,2858 cd·m-2和1985 cd·m-2.在掺杂质量百分比浓度为1.0%时,NRD2的发光峰值为558 nm,在电压为12 V时,发光亮度达到938 cd·m-2.     

高效稳定性有机黄光电致发光器件

主要通过红绿磷光材料R-4B和GIr1掺杂的方法,制备了黄光OLED器件,器件结构为ITO/MoO3(X)/NPB(40nm)/TCTA(10nm)/CBP:GIr1 14%:R-4B2%(30nm)/BCP(10nm)/Alq3(40nm)/LiF(1nm)/Al(100nm),TCTA和BCP分别为电子和空穴阻挡材料,同时结合TCTA和BCP对载流子的高效阻挡作用,研究了MoO3对器件效率和稳定性的影响。发现当增加MoO3的厚度为90nm时,在较大的电压范围内,器件都具有较高的效率和色坐标稳定性。在电流密度为7.13mA/cm2时,器件达到最高电流效率29.2cd/A,亮度为2081cd/m2;电流密度为151.7mA/cm2时,获得最高亮度为24430cd/m2,电流效率为16.0cd/A;器件色坐标稳定性较好,当电压为5、10、15V时,色坐标分别为(0.5020,0.4812)、(0.4862,0.4962)、(0.4786,0.5027)。器件性能的改善主要归因于载流子注入与传输的平衡以及阻挡层对发光区域的有效限定。     

一种含铱共聚物及其性能与应用

采用差示扫描量热法(DSC)和热重分析法(TGA)研究了一种含铱配合物的新型共聚物PVKIr的热性能。结果表明,该聚合物的玻璃化转变温度(Tg)为220.04℃,起始分解温度(Td)为454.31℃,具有良好的热稳定性。利用该聚合物为发光材料制备了电致发光器件ITO/聚(3,4-乙撑二氧噻吩)(PEDOT)(45nm)/2-(4-联苯基)-5-(4-叔丁基苯基)-1,3,4-口恶二唑(PBD):25%PVKIr(80nm)/2,9-二甲基-4,7-二苯基-1,10-菲咯啉(BCP)(15nm)/三(8-羟基喹啉)铝(Alq3)(30nm)/LiF(1nm)/Al,其最大发射峰在532nm,起亮电压为13V。该器件在驱动电压为21V时,达到最大亮度86cd/m2,而此时电流密度为192mA/cm2。     

高效单发光层绿色有机发光二极管的制备与性能研究

为了提升绿色有机发光二极管的效率,设计了阶梯能级结构的器件,使得载流子在器件中更有效传输,进而有效减缓了器件效率的衰减。选择热致延迟荧光材料(4s,6s)-2,4,5,6-四(9-氢咔唑-9-基)间苯二腈(4CzIPN)作为发光材料,并将其掺杂到能级匹配的主体材料1,3-二(咔唑-9-基)苯(mCP)中构成发光层,制备了一系列单发光层的绿色有机发光二极管。在发光材料的掺杂浓度为2%(wt,质量分数),发光层的厚度为20nm条件下,制得的器件性能最佳,其启亮电压为3.4V,其最大亮度、电流效率、功率效率和外量子效率分别为20706cd/m~2、50.49cd/A、41.96lm/W和16.7%。在亮度为1000cd/m~2条件下,其电流效率和外量子效率仍然高达34.06cd/A和11.6%。器件显示主峰位于504nm的4CzIPN特征发射,随着掺杂浓度的提升,越来越多的电子和空穴被4CzIPN分子所俘获,导致主体材料mCP的特征发射峰逐渐减弱。     

2-甲基-8-羟基喹啉镓配合物的合成及发光性能研究

合成了2-甲基-8-羟基喹啉镓配合物(Ga(mhq)3),通过红外光谱、氢核磁谱确认其结构,进一步通过紫外-可见吸收光谱、循环伏安曲线、荧光发射光谱和电致发光光谱表征了其光学带隙及发光性质。实验结果表明Ga(mhq)3紫外吸收峰在259和365nm处,由紫外吸收得到光学带隙为3.10eV。在四氢呋喃溶液中,416nm激发下,荧光发射峰在496nm,为蓝绿色荧光;在360nm波长的激发下,Ga(mhq)3粉末发射峰在472nm处,属蓝绿光发射。将其做成器件A:ITO/NPB(50nm)/Ga(mhq)3(30nm)/LiF(1nm)/Al(100nm),得到最大亮度为901.5cd/m2,最大发射波长为508nm。加入电子传输层Alq3对器件A进行优化后,最大亮度达到4339cd/m2。     

空穴注入层MoO_3厚度对蓝绿色磷光OLED发光特性的影响

以mCP为磷光主体材料,BGIr1为蓝绿色磷光掺杂材料,MoO3为空穴注入材料,制备5种不同厚度的MoO3蓝绿色磷光有机电致发光器件(OLED),并研究不同厚度MoO3空穴注入层对蓝绿色磷光OLED发光特性的影响。所制器件结构为ITO/MoO3(x nm)/NPB(40nm)/mCP∶BGIr1(30nm,18%)/BCP(10nm)/Alq3(20nm)/LiF(1nm)/Al(100nm),其中18%为发光层中BGIr1的掺杂量(质量分数),x为空穴注入层MoO3的厚度。研究结果表明,本实验制备器件空穴注入层MoO3的最佳厚度为20nm。当电压为13V时,MoO3厚度为20nm器件获得最大亮度为8 617cd/cm2,当电流密度为20mA/cm2时,器件获得最大发光效率为5.7cd/A。器件在488和512nm处获得两个主发射峰,发光颜色稳定,CIE坐标为(0.19,0.21)。     

DCJTB掺杂的荧光型白光有机电致发光器件

本文基于为ITO/2-TNATA(20 nm)/NPB(30 nm)/BePP2:DCJTB(45 nm:X%)/Alq3(30 nm)/LiF(1 nm)/Al(100 nm)的白光器件结构(X为DCJTB的掺杂浓度(质量分数))。采用真空热蒸镀的方法,在高精度膜厚测控仪的监控下分别制备了发光层掺杂浓度为1,1.5,2.0,2.5,3.0不同器件,并对各器件性能进行了测试。实验结果表明:当DCJTB的掺杂浓度为2.0%时,平衡了器件中电子和空穴的传输能力,使载流子复合形成激子的几率增加,既使载流子的传输能力明显改善,并且有效地抑制了器件的荧光猝灭效应。在12 V电压下,可以获得发光亮度最高达到9 868cd/m2,发光效率大于7.2 cd/A,且色坐标为(0.334,0.337)的较理想白光有机发光器件。     

PtOEP掺杂Alq3有机发光器件的能量传递

研究了高效磷光染料八乙基卟啉铂(PtOEP)掺杂于主体材料八羟基喹啉铝(Alq3)体系中PtOEP、Alq3之间的能量传输机制.分别以PtOEP掺杂和未掺杂的Alq3膜作为发光层制作有机发光器件(OLED),改变掺杂浓度,检测器件电致发光(EL)光谱的变化.经分析,在5%、10%、20%三种掺杂浓度中,10%掺杂浓度能量传递效果最好.通过对掺杂和未掺杂器件电流密度-电压、亮度-电压数据检测,计算外量子效率,在低电流密度(《7mA/cm2)驱动下掺杂器件外量子效率是未掺杂器件的5倍.     

基于新型红色材料的有机发光二极管

对一种名为N，N－双－[4-2-(4-二氰甲烯基－6－甲基）－4H－吡喃－2－基]乙烯基]苯基苯胺的新型有机红色材料（BDCM）进行了薄膜发光行为的研究，此材料的一个三苯胺（给电子基）和两个二氰甲烯吡喃（受电子基）所形成的较好空间位阻和强荧光发射能力，使得其固体薄膜具有很高的红色荧光量子产率。所构成ITO／CuPc/DPPP/BDCM/Mg:Ag的红色薄膜电致发光器件，在外加19V直流电压时达到582cd/m^2的发光亮度，同时，此器件的发光色度具有不随所加电流密度变化而改变的特点，表明此材料有很好的电子传输和红色发射性能。     

以萘为π-中心的双芪类衍生物的电致发光特性研究

以自制的"D-π-D"对称型有机绿色发光分子1,4-双(4'-N,N-二甲基氨基苯乙烯基)萘(简称 BMABN)为发光层,在结构为ITO/NPB/BMABN/BCP/Mg∶Ag的器件中,研究了空穴阻挡层厚度对器件发光性能的影响.结果表明,空穴阻挡层的增厚使得器件的起亮电压有所增加,但器件的亮度、电流效率和稳定性显著增加.该器件在5V开启,18V电压下亮度和效率分别为2000cd/m2和0.4lm/W.     

Fabrication and enhanced visible light photocatalytic activity of fluorine doped TiO2 by loaded with Ag

F-doped TiO2 loaded with Ag (Ag/F-TiO2) was prepared by sol-gel process combined with photoreduction method. The physical and chemical properties of the prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). XPS analysis indicated Ag species existed as Ag0 in the structure of Ag/F-TiO2 samples. UV-Vis diffuse reflectance spectra showed that the light absorption of Ag/F-TiO2 in the visible region had a significant enhancement compared with the F-doped TiO2 (F-TiO2). PL analysis indicated that the electron-hole recombination rate had been effectively inhibited when Ag loaded on the surface of F-TiO2. The photocatalytic activities of the samples were evaluated for the degradation of X-3B (Reactive Brilliant Red dye, C.I. reactive red 2) under visible light (lambda > 420 nm) irradiation. Compared with F-TiO2, the sample of 0.50 Ag/F-TiO2 showed the highest photocatalytic activity. The interaction between F species and metallic Ag was responsible for improving the visible light photocatalytic activity.     

磁控溅射法制备TiO2空穴缓冲层的有机发光器件

采用磁控溅射方法在ITO表面制备了不同厚度的TiO2超薄膜用做有机发光二极管（OLEDs）的空穴缓冲层,使OLEDs（ITO／TiO2／TPD／Alq3／Al）的发光性能得到很大改善。研究TiO2缓冲层厚度对器件性能影响的结果表明,当TiO2缓冲层厚度为1nm,电流密度为100mA／cm^2时,器件的发光效率为2cd／A,比未加缓冲层器件的发光效率增加了近一倍。这是由于加入适当厚度的TiO2缓冲层限制了空穴的注入并且提高了空穴与电子注入之间的平衡。     

Fabrication of nano-sized emitting phosphors for photoluminescence films via hydro-thermal synthesis

Nano-sized red and blue emitting phosphors for a photoluminescence film were fabricated via hydrothermal synthesis through the sol-gel process. The nano-sized phosphors had a spherical shape such as the 60-110 nm Y2O2S:Eu3+ phosphor and the 45-90 nm of Y2SiO5:Ce phosphor. Firing at 1000 degrees C for 2 hours resulted in an increase in their size to 90-190 nm for the Y2O2S:Eu3+ phosphor and 70-160 nm for the Y2SiO5:Ce phosphor. Heat treatment of the gel powders of the emitting phosphors above 730 degrees C was recommended because of their crystallization. The maximum excitation and emission intensities of the red and blue phosphors with Y2O2S:Eu3+ and Y2SiO5:Ce were at the wavelengths of 308 nm and 617 nm, and 254 nm and 464 nm, respectively. The photoluminescence of the films increased as increasing the content of the red and blue phosphor powder mixture in the plastic films. The 100 microm-thick PVB film with the nano-sized phosphors showed the maximum photoluminescence of 537 x 1000 counts/sec.     

Control of resonant wavelength from organic light-emitting materials by use of a Fabry-Perot microcavity structure

We report the fabrication of Fabry-Perot microcavity structures with the organic light-emitting material tris-(8-hydroxyquinoline) aluminum (Alq3) and derive their optical properties by measuring their photoluminescence (PL) and absorption. Silver and a TiO2-SiO2 multilayer were used as metal and dielectric reflectors, respectively, in a Fabry-Perot microcavity structure. Three types of microcavity were prepared: type A consisted of [air[Ag[Alq3]Ag]glass]; type B, of [air[dielectric[Alq3]dielectric]glass]; and type C, of [air[Ag[Alq2]dielectric]glass]. A bare Alq3 film of [air[Alq3]glass] had its PL peak near 514 nm, and its full width at half-maximum (FWHM) was 80 nm. The broad FWHM of a bare Alq3 film was reduced to 15-27.5, 7-10.5, and 16-16.6 nm for microcavity types A, B, and C, respectively. Also, we could control the PL peak of the microcavity structure by changing the spacer thickness, the amount of phase change on reflection, and the angle of incidence.     

Highly efficient blue light-emitting materials based on arylamine substituted DPVBi derivatives

A series of arylamine substituted DPVBi derivatives (1-4) were synthesized via the Horner-Wadsworth-Emmons reaction. Their electroluminescent properties were examined by fabricating a multilayer OLED device with the following structure: ITO/DNTPD (40 nm)/NPB (20 nm)/2% DPVBi derivatives (1-4) doped in MADN (20 nm)/Alq3 (40 nm)/Liq (1.0 nm)/Al. All devices showed efficient blue emission. In particular, a high efficiency blue OLED was fabricated using compound 1 as a dopant in the emitting layer. The maximum luminance, luminous efficiency, power efficiency and CIE coordinates of the blue OLED using compound 1 as a dopant were 16110 cd/m2 at 10 V, 10.1 cd/A at 20 mA/cm2, 4.37 Im/W at 20 mA/cm2, and (x = 0.197, y = 0.358) at 8 V, respectively. Moreover, a device using compound 4 as the dopant exhibited efficient deep blue emission with a luminance, luminous efficiency, power efficiency and CIE coordinates of 7005 cd/m2 at 10 V, 6.25 cd/A at 20 mA/cm2, 2.50 Im/W at 20 mA/cm2 and (x = 0.151, y = 0.143) at 8 V, respectively.     

Pure red organic electroluminescent devices using a novel europium(III) complex as emitting layer

Stable vacuum deposition of a new europium(III) complex, Eu(DBM)₃(L) {DBM=dibenzoylmethanato, L=3-ethyl-2-(4′-dimethylaminophenyl)imidazo[4,5-f]1,10-phenanthroline}, were verified by ultraviolet–visible and infrared spectroscopy. By using the vacuum deposited film of the Eu(III) complex as the emitting layer, aluminum tris(8-hydroxyquinolinate) (AlQ) as electron-transporting layer, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) as hole-blocking layer, N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine (TPD) as hole-transporting layer, a four-layer electroluminescent device of (+)indium–tin oxide/TPD(40 nm)/Eu(DBM)₃(L)(40 nm)/BCP(10 nm)/AlQ(40 nm)/Mg:Ag(110 nm)/Ag(60 nm)(−) gave high efficient and pure red light emission with a luminance of 230 cd/m². A comparison of the electroluminescence properties of the four-layer device with those of a two-layer and a three-layer device was made.     

Synthesis and luminescence properties of Sr2SiO4: Eu3+, Dy3+ phosphors by the sol-gel method

The Sr2SiO4:Eu3+, Dy3+ phosphors for white light emitting diodes (LEDs) were synthesized by the sol-gel method. The microstructure and luminescent properties of the obtained Sr2SiO4:Eu3+, Dy3+ particles were well characterized. The results demonstrate that the Sr2SiO4:Eu3+, Dy3+ particles, which have spherical morphology, emitted an intensive white light emission under excitation at 386 nm. The phosphors show three emission peaks: the blue emission at 486 nm corresponding to the 4F(9/2)-6H(15/2) transition of Dy3+, the yellow emission at 575 nm corresponding to the 4F(9/2)-6H(13/2) transition of Dy3+, and the red emission at 615 nm corresponding to the 5D0-7F2 transition of Eu3+. At the same time, the effect of Eu3+ concentration on the emission intensities of Sr2SiO4:Eu3+, Dy3+ was investigated in detail. The phosphors used for white LEDs were obtained by combining near ultraviolet (NUV) light (386 nm) with Sr2SiO4:0.04Dy3+, 0.01Eu3+ phosphors with the characteristic of Commission Internationale de l'Eclairage (CIE) chromaticity coordinate (x, y) of (0.33, 0.34), and color temperature Tc of 5,603 K. In addition, the effect of the charge compensators (Li+, Na+, and K+ ions) on the photoluminescence (PL) emission intensities were studied.     

Microstructure and optical properties of Ag-doped ZnO nanostructures prepared by a wet oxidation doping process

Silver-doped zinc oxide (Ag:ZnO) nanostructures were prepared by a facile and efficient wet oxidation method. This method included two steps: metallic Zn thin films mixed with Ag atoms were prepared by magnetron sputtering as the precursors, and then the precursors were oxidized in an O(2) atmosphere with water vapour present to form Ag:ZnO nanostructures. By controlling the oxidation conditions, pure ZnO and Ag:ZnO nanobelts/nanowires with a thickness of ～ 20 nm and length of up to several tens of microns were synthesized. Scanning electron microscopy, transmission electron microscopy, cathodoluminescence and low temperature photoluminescence (PL) measurements were adopted to characterize the microstructure and optical properties of the prepared samples. The results indicated that Ag doping during magnetron sputtering was a feasible method to tune the optical properties of ZnO nanostructures. For the Ag:ZnO nanostructures, the intensity of ultraviolet emission was increased up to three times compared with the pure ones. The detailed PL intensity variation with the increasing temperature is also discussed based on the ionization energy of acceptor in ZnO induced by Ag dopants.     

Substituent effect on color tuning of red light emission in photoluminescence and electroluminescence of red fluorophore

Typical small red light-emitting molecules for organic light emitting diodes (OLEDs) were highly susceptible to fluorescence concentration quenching in solid state. Red fluorophores, (2Z, 2'Z)-3, 3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-29',5'-diyl]bis(2-phenylacrylonitrile) (ABCV-P), (2E, 2'E)-3,3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2',5'-diyl]bis[2-(2-thienyl)acrylonitrile] (ABCV-Th) and (2Z, 2'Z)-3,3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2',5'-diyl]bis[2-(2-naphthyl)acrylonitrile] (ABCV-Np), capable of preventing fluorescence concentration quenching were designed and synthesized. These compounds have intramolecular charge transfer (ICT) properties which were estimated by measurement of UV-Visible absorption and photoluminescence (PL) emission spectra with variation of solvent polarity (n-Hexane/Chloroform = 99/1, 1/1; Chloroform; Methylene chloride). The magnitude of ICT for ABCV-Th was measured to be the largest and that for ABCV-Np was slightly larger compared to that for ABCV-P. The magnitude of ICT resulted in a shift of peak wavelength of PL emission. Therefore, this result well supported substituent effect on the color change of PL emission. The peak wavelengths of photoluminescence for ABCV-P, ABCV-Np and ABCV-Th were observed to be 607.5, 611.5 and 617.5 nm, respectively, and those of EL spectra were measured to be 612.5, 619.5, 621.0 nm, respectively. The emission maxima of PL and EL spectra for these red fluorescent compounds were well correlated with substituent effect on ICT for them.     

Hydrothermal synthesis and optical properties of Eu(3+)-doped CaSnO3 nanocrystals

In this paper, CaSnO3:Eu3+ nanocrystals were prepared by hydrothermal synthesis method. The influence of different molar ratio of Ca:Sn on structure of CaSnO3:Eu3+ was investigated by using X-ray powder diffraction (XRD). Well-crystallized and phase-pure CaSnO3:Eu3+ particles of approximately 90 nm in size can be readily obtained at 900 degrees C. Furthermore, photoluminescence characterization of the Eu(3+)-doped CaSnO3 nanocrystals was performed and discussed. The emission peak situated at 618 nm showing prominent and bright red light is due to the 5D0-7F2 electric dipole transition. The excellent luminescence properties make it possible as a good candidate for PDP application.