Electrosynthesis of poly（o-phenylenediamine） in ionic liquid and its properties

Ionic liquid 1-ethyl-3-methylimidazolium bromide (EMIMBr) and N-methylimidazolium tetrafluorobo-rate (HMIMBF4) have been used as solvent and electrolyte for the electropolymerization of o-phenylenediamine at glassy carbon electrode by cyclic voltammetry. It was found that monomer was more easily oxidized in ionic liquid than acidic aqueous solution,and oxidative potential was reduced by 0.725 and 0.455 V,respectively. Electrode modified with poly(o-phenylenediamine) (PPD) has obvi-ous electrochemical activity in acid solution (pH 1-4). The apparent diffusion coefficient (Dapp) of PPD film is measured by chronocoulometry and chronoamperometry. The polymer structure is measured by UV and IR. IR spectrometry reveals that poly(o-phenylenediamine) has phenazine ring structure. The heat stability of polymer is observed from thermogravimetry.     

Hybrid solar cells based on poly（3-hexylthiophene） and electrospun TiO2 nanofibers modified with CdS nanoparticles

Organic–inorganic hybrid solar cells based on poly(3-hexylthiophene) and electrospun TiO2 nano bers were fabricated by solution process.The ef ciency of the device was improved by modifying CdS nanoparticles on the surface of TiO2 by electrochemical method.The CdS layer can lead to the increase of both open circuit voltage and short circuit current of the device,which are attributed to enhanced exciton dissociation and light absorption and suppressed carrier recombination by CdS at the heterojunction.However,too thick CdS layer led to increased series resistance and decreased ef ciency of the device.Therefore,the optimum condition of the CdS deposition was obtained,which increased the power conversion ef ciency of the device for about 50%.Our results indicate that the surface modi cation on the inorganic semiconductor layer is an effect way to improve the performance of the hybrid solar cells.     

Local electronic structure and magnetic properties of （Ga,Cr）N

Modern electronic devices utilize the charge degree of freedom of electrons to process information in semiconductors and the spin degree of freedom to store information in magnetic materials. For example, inte- grated circuits and high–frequency devices …     

Structural and optical properties of Zn1−xNixTe thin films prepared by electron beam evaporation technique

Zn1-xNixTe thin films with different composition(x=0.0, 0.05, 0.10, 0.15 and 0.20) were deposited on glass substrate by electron beam evaporation technique followed by its characterization using advanced structural and optical analysis techniques. Structural properties of the prepared thin films were studied by X-ray diffraction(XRD). The XRD patterns revealed that the binary compounds transformed into a ternary compound with cubic structure having preferred orientation along the c-direction with(111) planes. Composition analysis of the films was determined by energy dispersive analysis of X-rays(EDAX) and found to be in agreement with the precursor composition. Optical properties such as extinction coefficient(k) and band gap energy of these films were examined by using a spectroscopic ellipsometer. It was found that the extinction coefficient(k) increased with the addition of Ni content in the alloy. In comparison, the band gap energy was also determined by using transmission spectra and found to be agreed with that of the ellipsometric results. These analyses confirm that the band gap energy decreases with the increase of Ni content in the alloy.     

Investigation of the electronic structure and photoluminescence properties of Eu3＋ in Sr2Mgl_xZnxSi207 （0 〈x 〈 1）

Undoped and Eu 3+-doped Sr 2 Mg 1-x Zn x Si 2 O 7 (0≤x≤1) powder crystals were obtained by conventional solid-state reaction.X-ray diffraction,inductively coupled plasma analysis,and Fourier transform infrared spectroscopy results implied that a complete solid-solution formed between Sr 2 MgSi 2 O 7 and Sr 2 ZnSi 2 O 7 as well as local structural adjustment.Excitation spectra exhibited O 2-Eu 3+ charge transfer (CT) bands centered at 250 nm for Sr 2 MgSi 2 O 7:Eu 3+ and 258 nm for Sr 2 ZnSi 2 O 7:Eu 3+.Emission spectra exhibited a major band around 616 nm,which showed the environment around Eu 3+ was non-centrosymmetric in both Sr 2 MgSi 2 O 7:Eu 3+ and Sr 2 ZnSi 2 O 7:Eu 3+.In addition,first principles calculations within the local density approximation (LDA) of density functional theory (DFT) were used to calculate the electronic structure of Sr 2 MgSi 2 O 7 and Sr 2 ZnSi 2 O 7.Calculated results were correlated with experimental UV-vis reflection spectra and the observed shift of the O 2-Eu 3+ CT band.     

Restoration of rat calvarial defects by poly（lactide-co-glycolide）/ hydroxyapatite scaffolds loaded with bone mesenchymal stem cells and DNA complexes

A composite construct comprising of a bone mesenchymal stem cell (BMSC) sheet, plasmid DNA, encoding human bone morphogenic protein-2 (hBMP-2), and poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) sponge was designed and employed in the restoration of rat calvarial defects. To improve gene transfection efficiency, a cationic chitosan derivative, N,N,N,-trimethyl chitosan chloride (TMC), was employed as the vector. The TMC/DNA complexes had a transfection efficiency of 13% in rat BMSCs, resulting in heterogeneous hBMP-2 expression in a 10-d culture period in vitro. In vivo culture of the composite constructs was performed by implantation into rat full-thickness calvarial defects, using constructs lacking pDNA-hBMP-2 or BMSC sheets as controls. Significantly higher heterogeneous expression of hBMP-2 was detected in vivo at 2 weeks for the cell sheet/DNA complex/scaffold constructs, compared with the constructs lacking pDNA-hBMP-2 or BMSC sheets. New bone formation was evident as early as 4 weeks in the experimental constructs. At 8 weeks, partial bridging of calvarial defects was observed in the experimental constructs, which was significantly better than the constructs lacking pDNA-hBMP-2 or BMSC sheets. Therefore, the combination of the PLGA/HA scaffold with BMSC sheets and gene therapy vectors is effective at enhancing bone formation.     

Synthesis and assembly with mesoporous silica of platinum （Ⅱ） porphyrin complexes bearing carbazyl groups： Luminescent and oxygen sensing properties

A series of platinum meso-tetrakis [3-methoxy-4-（N-carbazyl）n-alkyloxyphenyl]porphyrin （Pt-4Cn-TPP, n = 4, 6 and 8） are synthesized. Pt-4C4-TPP, Pt-4C6-TPP and Pt-4C8-TPP exhibit similar luminescent properties in solution and solid state. Three protonated platinum （Ⅱ） porphyrins are assembled with mesoporous silica MCM-48, respectively, resulting in assembly materials Pt-4Cn-Tpp^4＋/ MCM-48 （n = 4, 6 and 8）. The luminescent intensity of Pt-4Cn-Tpp4^＋/MCM-48 can be extremely quenched by molecular oxygen with high sensitivity （I0/I100 〉 9）. The Stern-Volmer plots of these assembly materials display considerable linearity within a wide range of oxygen concentration （0 to 100%）. The response time is all≤ 1 s and recovery time ≤ 22 s for these assembly materials.     

Conformations and adsorption behavior of poly（allylamine hydrochloride） studied by single molecule force spectroscopy

Poly（allylamine hydrochloride） （PAH）, which is frequently used in fabricating polyelectrolyte multilayer films, was studied by single molecule force spectroscopy （SMFS）. Plenty of force-extension curves with a long plateau were obtained in water, indicating that train-like structure was predominant when PAH was adsorbed on the substrate. It was found that the peak-type force-extension curves of PAH in water were not able to be fitted by the modified freely-jointed chain model. Additionally, there was a flat region in the derivative of force-extension curves. Thus, it was inferred that PAH chain in water was in a special conformation and underwent a ＂conformational transition＂ under the stretching of an external force. This phenomenon did not appear in the SMFS experiment in 1 mol/L urea solution, which indicated that urea was able to break the special conformation.     

Preparation of MCM-41-supported chiral Salen Mn （Ⅲ） catalysts and their catalytic properties in the asymmetric epoxidation of olefins

A secondary amino-modified mesoporous molecular sieve MCM-41 was obtained by reaction of bis(3-(triethoxysilyl)propyl)amine with MCM-41. The chiral Salen-Mn (III) complex was anchored onto the modified MCM-41 by a multi-step grafting method and two heterogenized catalysts with different Mn contents were obtained. The catalysts were characterized by XRD, N2 adsorption, ICP, FT-IR and DR UV-Vis. Their catalysis on asymmetric epoxidation of several olefins was studied with NaClO and m-CPBA as oxidants respectively. It was found that both the activity and enantioselectivity of the cata- lysts decreased after the homogeneous catalyst was heterogenized. The reasons resulting in the de- crease of catalytic performance were discussed.     

Prostate cancer targeted MRI nanoprobe based on superparamagnetic iron oxide and copolymer of poly（ethylene glycol） and polyethyleneimin

Methoxyl poly （ethylene glycol） （mPEG-OH） was successfully grafted onto branched polyethyleneimine （hy-PEI） to yield a water soluble graft copolymer mPEG-g-PEI. This copolymer may package superparamagnetic iron oxide （SPIO） by ligand exchange. The SPIO weight percentage in the polymer coated nanoparticles was determined to be 55%, the size and zeta potential of nanoparticles was 50 nm and 12 mV respectively. Antibody fixation onto the complex （mPEI-g-PEG-SPIO） surface layer was achieved by activated single chain monoclonal antibody against prostate stem cell antigen （PSCA）. Our study showed that the single chain antibody functionalized nanoprobe （scAbpscA-PEI-g-PEG-SPIO） with a small size can specifically enter the prostate cancer cells, decreasing MRI T2-weighted signal intensity of prostate cancer cells to 44.76%, Our results revealed that the potential of this magnetic nanoparticulate system promised as a novel MRI nanoprobe for early diagnosis of prostate cancer （PCa）.     

一种咔唑-苯并噻二唑共聚物的合成与光伏性能研究

以N-十二烷基-2,7-咔唑为给体单元、5,6-二辛氧基二噻吩苯并噻二唑为受体单元，通过Suzuki偶联反应合成了一种具有给-受体结构的共轭聚合物聚N-十二烷基-2,7-咔唑-5,6-二辛氧基-4,7-二噻吩-2-基-苯并噻二唑（PC-DODTBT），并研究了该聚合物的光物理与电化学性能。结果表明，以PC-DODTBT为电子给体，PCBM为电子受体，制得的共混体相异质结太阳能电池在AM1.5、100 mW/cm²模拟太阳光下，开路电压为0.88 V，短路电流为2.04 mA/cm²，填充因子为0.51，能量转换效率为0.92%。     

聚9,9-双(丙酸乙酯基)芴的合成及性能研究

以丙烯腈为烷基化试剂，以工业芴为原料，在温和的条件下合成了9，9—双取代芴单体，并以FeCl3为聚合催化剂，合成了可溶性的聚芴衍生物聚9，9—双(丙酸乙酯基)芴，采用元素分析，Fr—IR，TGA，GPC，UV—Vis和荧光光谱等对单体和聚合物结构和性能进行了表征，实验结果表明：所采用的方法是一种实用的制备9，9—双取代芴的简便方法，所获得的聚合物在溶液和薄膜状态具有强烈的蓝色荧光发射，在相同浓度时溶剂不影响发光波长，而对发光强度有明显的影响，在同一溶剂中，随聚合物浓度减小，发光波长蓝移，聚合物在氮气和空气中具有高热稳定性。     

新颖苝四羧酸亚胺系化合物的光电互转换性质研究

合成了Ｎ，Ｎ＇－二正丙基－１，６，７，１２－四苯氧基－３，４，９，１０－苝四羧酸亚胺（ＰＴＣ）。利用真空镀膜技术制备了Ａｌ－ＰＴＣ－Ａｇ（Ｃｅｌｌ－Ａ）和ＩＴＯ－ＰＴＣ－Ａｇ（Ｃｅｌｌ－Ｂ）两种光电池以及ＩＴＯ－ＰＴＣ－Ｚｎｑ_２－Ａｌ（ＬＥＤ－Ｃ）双层结构的电致发光二极管。测试光电性能得：Ｃｅｌｌ－Ａ具有光生伏打效应，Ｃｅｌｌ－Ｂ没有，ＬＥＤ－Ｃ发出λ＝５５０ｎｍ的黄绿光，故ＰＴＣ具有Ｐ型半导体性质。     

The effect of spacer in hybrid white organic light emitting diodes

Two kinds of highly efficient,bright hybrid white organic light emitting diodes have been fabricated by utilizing ambipolar material 4,4-N,N-dicarbazolebiphenyl(CBP)and unipolar material N,N0-di(naphthalene-1-yl)-N,N0-diphenyl-benzidine(NPB)as the spacer,respectively.By adjusting the thickness of spacers together with effectively utilizing combinations of exciton-harnessed orangephosphorescence/blue-fluorescence,the current efficiency of optimal device with CBP spacer and device with NPB spacer are 31.0 and 38.9 cd/A,the maximum power efficiency are 23.9 and 29.1 lm/W,the maximum brightness are 87,249 and 75,501 cd/m2,and the Commission Internationale de l’Eclairage(CIE)coordinates are(0.42,0.43)and(0.47,0.44)at a voltage of 11 V,respectively.Furthermore,systematic investigations focused on the effects of spacers on device performance have been performed.By virtue of the multifunctional spacer,energy transfer between the phosphorescent and fluorescent emitters can be avoided while the carriers still can pass through this spacer bridge,which is important to realize such high device performance.In addition,a novel concept that both ambipolar materials and unipolar materials can be the promising candidates for spacers has been proposed if the thickness of spacers with high triplet energy is optimized.     

Tunable and enhanced luminescence of Ba2−xCaxSiO4−yN2/3y:Eu2+ phosphors for white light-emitting diodes

Color tuning and luminescence enhancement are predominant challenges for improving the performance of white light emitting diodes(LEDs) toward commercial application. In this paper, a novel promising Ba_(2-x)Ca_xSiO_(4-y)N_(2/3y):Eu~(2+) tphosphors with tunable and enhanced luminescence for phosphors converted LEDs(pc-LEDs) have been successfully synthesized by a direct gas-reduction nitridation method. The effects of Ca and N doping on the phase purity, morphology and optical properties of Ba_(2-x)Ca_xSiO_(4-y)N_(2/3y):Eu~(2+) tphosphors were also systematically investigated. The optical results show that Ba_(2-x)Ca_xSiO_(4-y)N_(2/3y):Eu~(2+) tphosphors can be actively excited over a broad range from 250 to430 nm. With the adding of different concentrations of Ca~(2+) tions in phosphors, the emission color wavelength can be tailored from 501 to 441 nm by a 375 nm NUV LED excitation source. Furthermore, it has been found that the emission and absorption of Ba_(2-x)Ca_xSiO_(4-y)N_(2/3y) tphosphor can be significantly improved when N~(3-) ions were introduced into the host lattices. The intensity of Ba_(1.5)Ca_(0.5)SiO_(4-y)N_(2/3y):Eu~(2+) tphosphor was 3.4 times higher than the phosphor without N doping. The fabrication and characterization of pc-LEDs using Ba_(2-x)Ca_xSiO_(4-y)N_(2/3y):Eu~(2+) tphosphors-silica gel as the coating layer onto 375 nm-emitting In Ga N LED caps demonstrated the superior optical and current tolerant properties,making it a promising and competitive candidate for commercial utilization in white LED applications.     

The spectroscopic properties of Dy3+and Eu3+ co-doped Y3Al5O12 (YAG) phosphors for white LED

Tunable full color emissive Y32.94-xAl5O12: 0.06 Dy3+, xEu3+(YAG: 0.06 Dy, xEu) phosphors with emission peaks at 483 nm(blue), 582 nm(yellow) and 610 nm(red) were synthesized by a sol–gel method. The as-synthesized phosphors were characterized by X-ray powder diffraction(XRD), transmission electron microscopy(TEM), photoluminescence decay lifetimes, photoluminescence excitation and emission spectra. The results showed that photoluminescence intensity varied with excitation wavelength and the doping concentration of Eu3+. The co-doping with Eu3+ compensated the red emission component of the YAG: Dy3+ phosphor. The chromaticity coordinate of YAG: 0.06 Dy, 0.09 Eu phosphor(0.3263, 0.3334) was very close to that of the ideal white light(0.3333, 0.3333). Thus, the YAG: 0.06 Dy, 0.09 Eu phosphor can find potential application in simulating the sunlight artificially through fabricating white light emitters.     

NPB/Alq_3有机发光二极管的光学模拟

采用偶极子源项和转移矩阵来描述结构内外的光电场分布,并通过Matlab编程,建立了符合有机发光二极管(OLED)实际器件的光学模型。利用该光学模型进行模拟计算具有NPB/Alq3结构的OLED,得到了电致发光(EL)光谱与器件中光出射角之间的关系并结合人眼视觉函数,得到器件亮度与角度的关系,当出射角度逐渐增大时,亮度逐渐减小。另外,制备了不同8-羟基喹啉铝(Alq3)电子传输层厚度的器件,并测量其电致发光光谱,发现模拟计算的理论光谱与测量结果相吻合。并且还发现随着Alq3有机层厚度增加,OLED电致发光光谱的峰位会发生一定的红移。     

WLED用铕激活正硅酸锶荧光体的光谱性质与晶相的关系

采用喷雾热解两步法、高温固相法分别制备了纯相的α’-Sr2SiO4:Eu2 和β-Sr2SiO4:Eu2 荧光体.利用高斯函数拟合,首次确定了每个物相荧光发射谱的具体峰位,即α’-Sr2SiO4:Eu2 的发射峰为489.1 nm/555.1 nm,β-Sr2SiO4:Eu2 的发射峰位为468.8 nm/539.7 nm/593.2 nm.发现β-Sr2SiO4:Eu2 中存在两个反常的发射峰,一个峰位随激发波长的变化而在局部出现振荡,另一个对于β-Sr2SiO4:Eu2 晶格而言是一个额外的发射峰.对于前者我们提出了一个简化的能级图来说明,后者我们确定其为磷光.解析物相与荧光光谱的对应关系,对于荧光体的改进和发光学理论研究都具有重要意义.     

聚合物电致发光二极管发光层中的电场分布

以单层聚对苯乙炔（PPV）薄膜发光二极管为例,研究其薄膜中的电场分布,探讨其电场分布对载流子注入、输运和复合的影响,研究结果有助于揭示其发光机理,为提高发光效率提供了有益的启示。     

有机电致发光器件自动测量系统

设计并组建了一套可精确测量有机电致发光器件(OLED)电流密度-电压-亮度以及衰减曲线(亮度随时间的衰减)的自动测量系统．该系统工作时由计算机通过RS-232接口控制Keithley 2400 Source Meter向待测器件提供稳压(稳流)并测量相应的电流(电压)，控制New Port 1800-C Power Meter同步检测待测器件的光功率．采集到的数据最终送入计算机中进行处理、绘制性能曲线及存储．使用本系统对以JBEM为基质的蓝色OLED进行了测量．