Luminescent and photovoltaic properties of poly（9,9-dioctylfluorene- co-bithiophene） in organic electronic devices

We studied the luminescent and photovoltaic properties of poly(9,9-dioctylfluorene-co-bithiophene)(F8T2) based on ITO/PEDOT:PSS/F8T2/Bphen/LiF(0 or 1 nm)/Al and ITO/PEDOT:PSS/F8T2:PCBM/Bphen/Al.A stable and bright yellow emission was obtained from polymer F8T2,and the electroluminescence power reached 45 ?W at a 15 V driving voltage.Polymer F8T2 shows a broad absorption band from 400 to 500 nm,and has a shorter absorption edge at about 560 nm compared to that of the typical electron donor P3HT(650 nm).The photoluminescence quenching of F8T2 occurs with only a small fraction of blended PCBM due to the effective exciton dissociation at the interface between F8T2 and PCBM.Polymer solar cells(PSCs) using F8T2:PCBM as the active layer show a low power conversion efficiency(PCE) of 0.10% with an open circuit voltage(Voc) of 0.91 V and short circuit current density(Jsc) of 0.23 mA/cm2.The PSCs using F8T2:P3HT:PCBM as the active layer have a Voc of 0.85 V and Jsc of 3.02 mA/cm2,improving the PCE by about 0.90%.We attribute the improved cell performance to the higher number of photons harvested by P3HT molecules.     

Preparation of porous nanoparticle TiO2 films for flexible dye-sensitized solar cells

A TiO2 paste was prepared by mixing commercial TiO2 (P25), ethanol, distilled water and a small amount of Ti (IV) tetrai-sopropoxide (TTIP), following by a hydrothermal treatment. Before hydrothermal treatment, a stirring for 48 h can prevent cracking TiO2 films. TTIP significantly promote the chemical connection between TiO2 particles and its adherence to the substrate, the TTIP amount of 6 mol% is suitable. UV irradiation can remove some impurities and water from the TiO2 film with an optimal time of 2 h. Transmission electron microscopy, X-ray diffraction, scanning electron microscopy and photovoltaic tests are charac- terized and measured. Shortcircuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiencies for the fabricated flexible dye-sensitized solar cell are 7.20 mA cm-2, 0.769 V, 0.686 and 3.84%, respectively, under irradiation with a simulated solar light of 100 mW cm-2.     

Application of upconversion luminescence in dye-sensitized solar cells

An upconversion luminescence powder TiO2:(Er3+,Yb3+) is prepared by a hydrothermal method and used to fabricate dye-sensitized solar cell (DSSC).The TiO2:(Er3+,Yb3+) powder undergoes upconversion luminescence,converting infrared light which the dye can not absorb into visible light with wavelengths of 510-700 nm which the dye can absorb,increasing the photocurrent of the DSSC.TiO2:(Er3+,Yb3+) also acts as a p-type dopant,heightening the Fermi level of the oxide film,which increases the photovoltage of the DSSC.The best performance of the DSSC is found when the ratio of TiO2/luminescence powder is 1/3 in the luminescence layer.Under simulated solar irradiation of 100 mW cm-2 (AM 1.5),the DSSC containing TiO2:(Er3+,Yb3+) doping achieves a light-to-electricity energy conversion efficiency of 7.28% compared with 6.41% for the undoped DSSC.     

Optimization of polymer electrolytes for quasi-solidstate dye-sensitized solar cells

The dye-sensitized nanocrystalline TiO2 thin filmsolar cells (DSSCs) have attracted much attention since1990s[1— , due to their high light to electrical energy 4]conversion efficiency. So far, many studies have beenmade on the use of liquid electrolytes such as acetonitrile,3-methoxypropionitrile and a mixture of ethylene/pro-pylene carbonate (EC/PC) containing I? /I3 redox cou-?ple. A light to electrical energy conversion efficiency of7%— 12% has been obtained for DSSC using liquid e…     

An acetylcholinesterase inhibitor, 3-benzidino-5-methyl-6-phenylpyridazine, blocking outward potassium currents in acutely isolated rat hippocampal pyramidal neurons

3-benzidino-5-methyl-6-phenylpyridazine (BMP) inhibited electric eel acetylcholinesterase (AChE), with IC50 being 0.58 μmol·L-1. As an AChE inhibitor, the effects of BMP on delayed rectifier potassium current (IK(DR)) and transient outward potassium current (IK(A)) in acutely isolated rat hippocampal pyramidal neurons were studied using the whole cell patch-clamp technique. BMP (0.1―50 μmol·L-1) inhibited IK(DR) and IK(A) in a concentration-dependent and voltage-independent manner. The IC50 value for the bl...     

Si衬底掺杂浓度对InGaN/Si异质单结太阳电池性能的影响

【目的】研究p-Si衬底掺杂浓度对InGaN/Si异质单结太阳电池性能的影响,为制备高效太阳电池提供理论基础。【方法】将器件的n-InGaN掺杂浓度固定为10~(16 )cm~(-3),在改变p-Si衬底掺杂浓度N_A的情况下,采用一维光电子和微电子器件结构分析模拟软件(AMPS-1D)对InGaN/Si异质单结太阳电池器件的各项性能参数进行模拟。【结果】随着掺杂浓度N_A的升高,电池的电流密度J_(SC)和填充因子FF随之升高,当到达一定高的掺杂浓度范围时(N_A5.00×10~(17)cm~(-3)),J_(SC)基本保持不变,约为28.12mA/cm~2,FF保持在0.85左右且变化不大。开路电压V_(OC)和光电转换效率E_(ff)与掺杂浓度的大小呈正相关关系,随着N_A的增大,V_(OC)、E_(ff)缓慢增大。【结论】高掺杂浓度下的太阳电池具有较好的光电转换效率。低掺杂浓度的太阳电池光电转换效率较低,这是因为其对应的尖峰势垒高度和宽度均较大,影响了光生载流子的输运。     

Chemical leaching of an Indian bituminous coal and characterization of the products by vibrational spectroscopic techniques

High volatile bituminous coal was demineralized by a chemical method. The vibrations of the "aromatics" structure of graphite, crystalline or non-crystalline, were observed in the spectra at the 1600 cm-1 region. The band at 1477 cm-1 is assigned as V_R band, the band at 1392 cm-1 as V_L band and the band at 1540 cm-1 as G_R band. Graphite structure remains after chemical leaching liberates oxygenated functional groups and mineral groups. The silicate bands between 1010 and 1100 cm-1 are active in the infrared (IR) spectrum but inactive in the Raman spectrum. Absorption arising from C-H stretching in alkenes occurs in the region of 3000 to 2840 cm-1. Raman bands because of symmetric stretch of water molecules were also observed in the spectrum at 3250 cm-1 and 3450 cm-1. Scanning electron microscopy analysis revealed the presence of a graphite layer on the surface. Leaching of the sample with hydrofluoric acid decreases the mineral phase and increases the carbon content. The ash content is reduced by 84.5wt% with leaching from its initial value by mainly removing aluminum and silicate containing minerals.     

TiO<Subscript>2</Subscript>@MgO core-shell film: Fabrication and application to dye-sensitized solar cells

In this study,TiO2@MgO core-shell film was obtained by using a simple chemical bath deposition method to coat a thin MgO film around TiO2 nanoparticles. The core-shell configuration was characterized by X-ray diffractometer (XRD),scanning elec-tron microscopy (SEM),energy dispersive X-ray spectroscopy (EDX),and high-resolution transmission electron microscopy (HRTEM). Lattice fringes were observed for the TiO2 particles,and the MgO shell showed an amorphous structure,revealing a clear distinction between the core and shell materials. Applying the core-shell film as photoanode to the dye-sensitized solar cells (DSSCs),it shows a superior performance compared to the pure TiO2 electrode. Under the illumination of simulated sunlight (75 mW-cm-2),the short circuit photocurrent (Jsc),the open circuit photovoltage (Voc),and the fill factor (fF) are 8.80 mA-cm-2,646 mV,and 0.69,respectively,and the conversion efficiency (η) in-creased by 21.8% (from 4.32% to 5.26%) when dipping for opti-mum condition.     

Laser cooling using anti-stokes fluorescence in Yb3+-doped fluorozirconate glasses

The fluorozirconate glasses ZBLANP (ZrF₄−BaF₂−LaF₃−NaF−PbF₂) doped with different Yb³⁺ concentration were prepared. The Raman spectra and absorption spectra are measured to substantiate the existence of phonon-assisted emission. After analyzing the normalized absorption spectra of samples with different Yb³⁺-doped concentration, we calculated the maximum cooling effect in the 3 wt% Yb³⁺-doped sample pumped at 1 012.5 nm. The corresponding cooling capability is about −4.09 °C/W and the cooling efficiency reaches 1.76%. Foundation item: Supported by the Key Science Foundation of Wuhan (9601P0223) Biography: Xu Tian-ming (1978-), female, Master candidate, research direction: information optics and nonlinear optics.     

Electronic structures and infrared spectra of C120O2, C120OS and C120S2

Electronic structures and infrared spectra of C₁₂₀XY molecules (X, Y=O, S) and some of the corresponding ions are investigated using PM3 semi-empirical molecular orbital calculations with full optimization of geometrical structures. It is found that the energy penalty is about 30–42 kJ/mol due to introducing a double bond in the fivemembered ring except for C₁₂₀O₂ ⁻ and triplet C₁₂₀O₂ ²⁻. It is also found that the structures of neutral molecules and the corresponding ions are almost the same; for instance, the change of bond length is less than 0.001 nm. The change of frontier orbits from oxide to sulfide is little as well. The triplet states of C₁₂₀O₂ ²⁻ and C₁₂₀OS²⁻ are more stable than their singlet states, which means that C₁₂₀O₂ ²⁻ and C₁₂₀OS²⁻ follow the Hund’s rule. The vibration analysis showed that the infrared spectra of neutral C₁₂₀O₂ and C₁₂₀OS molecules are in good agreement with the experimental results. Compared with the neutral molecule, vibration frequencies of triplet C₁₂₀O₂ ²⁻ change little, but the vibration intensities are enhanced obviously.     

Structural OH in mantle-derived clinopyroxene megacrysts from Nushan

Thirteen clinopyroxene megacrysts from Nushan Cenozoic basalts have been investigated by Fourier transform infrared spectrometer(FTIR). The results demonstrate that all samples contain trace amount of structural OH. Clinopyroxenes from Nushan show four groups of absorption bands, in which, 3 472–3 506 cm⁻¹ is the major characteristic one. It is suggested that the position of major band is probably related to AI content: the position of major characteristic band for high-AI samples is around 3 470 cm⁻¹, whereas that for low-AI samples around 3 620 cm⁻¹.     

Fluorescence and sensitization performance of phenylene-vinylene-substituted polythiophene

A new kind of polythiophene derivative, Poly(3-{2-[4-(2-ethylhexyloxy)-phenyl]-vinyl}-2,2′-bithiophene) (PTh), was applied in dye-sensitized solar cell to extend the light response of nanocrystalline TiO2 electrode. UV-vis absorption and fluorescence spectra were employed to investigate the interaction of PTh with nanocrystalline TiO2. The absorption coefficient of the PTh was high in visible part of spec- trum, and the fluorescence emission of the PTh can be efficiently quenched by TiO2 nanoparticles ow- i...     

Synthesis of meso-tetra-(2-chloro-4-sulfophenyl) prophyrin and spectrophotometric determination of trace amounts of cadmium

Synthesis of a new high sensitive water soluble chromogenic reagent meso-tetra-(2-chloro-4-sulfophenyl) prophyrin and the conditions for the reaction of this reagent with cadmium (I) were studied. The apparent molar absorption coefficient at 434 nm is 5.20×10⁵ L·mol⁻¹·cm⁻¹. The method has been applied to the determination of 5.0×10⁻⁹ (content by weight) Cadmium (I) in honey. Supported by the National Natural Science Foundatyion of China Xiao Ling: born in Oct. 1962, Ph.D gradute student     

Ionization and dissociation of CH<Subscript>2</Subscript>I<Subscript>2</Subscript> and CH<Subscript>2</Subscript>ICl in femtosecond intense field

With the development of ultrafast laser technique,the femtosecond laser electric field is comparable to themolecular field experienced by valence electrons. In thiscase, the classical quantum mechanical theory, based onperturbation theory, becomes inapplicable. Theoreticalunderstanding of the interaction of molecules with intenselaser radiation is quite difficult. The Coulomb explosionhas been extensively studied[1—10] and explained by somesemiclassical models, such as the above threshold ion…     

Raman spectroscopy of single quantum well wires

We used the micro-Raman spectroscopy to investigate the V-grooved quantum well wires (QWWs), and first observed and assigned the Raman spectra of single QWW. They were the disorder induced modes at 223 and 243 cm⁻¹, confined LO mode of GaAs QWW at 267 cm⁻¹, and higher order peaks of disorder induced modes at 488 and 707 cm⁻¹.     

Raman and infrared spectroscopic investigation of some hydrous LnTPPTS complexes (Ln=La,Sm)

The Raman and IR spectra of LnTPPTS·10H₂O [Ln=La,Sm, TPPTS=P(m-C₆H₄SO₃) ₃ ³⁻ ] complexes are reported. Based on the observed Raman and IR characteristic frequencies, a vibrational assignments has been made for these complexes. Coordination induces a lengthening of the S−O bonds and a shortening of the C−S bond. The C−S stretching frequencies should therefore increase while the position of the should move to a lower wavenumber. Vibrational modes of metal-oxygen polyhedron V _(La-O) at 146, 168,253 cm⁻¹ are the structural charactrization for coordinate bond of LnTPPTS complexes. Chen Zhenhua: Born in 1938, Professor     

The v-v energy transfer of highly vibrationally excited states (I)

The relaxation of the highly vibrationally excited CO (v = 1–8) by CO₂ is studied by timeresolved Fourier transform infrared emission spectroscopy (TR FTIR). 193 nm laser photolysis of the mixture of CHBr₃ with O₂ generates the highly vibrationally excited CO(v) molecules. TR FTIR records the intense infrared emission of CO(v→v-1). The vibrational populations of each level of CO(v) have been determined by the method of spectral simulation. Based on the evolution of the time resolved populations and the differential method, 8 energy transfer rate constants of CO(v = 1–8) to CO₂ molecules areobtained: (5.7±0.1), (5.9±0.1), (5.2±0.2), (3.4±0.2), (2.4±0.3), (2.2±0.4), (2.0±0.4) and (1.8±0.6) (10¹⁴ cm³ · molecule⁻¹ · s⁻¹), respectively. A two-channel energy transfer model can explain the feature of the quenching of CO(v) by CO². For the lower vibrational states of CO, the vibrational energy transfers preferentially to the u³ mode of CO² For the higher levels, the major quenching channel changes to the vibrational energy exchange between CO(v→v-1) and the u¹ mode of CO².     

Kinetic studies of the decomposition reaction of adducts of dinuclear Fe(Ⅱ)/O2

Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe₂(N-Et-HPTB){O₂P(OPh)₂}](Cl- O₄)₂ (1) and [Fe₂(N-Et-HPTB) {O₂P(Ph)₂}] (ClO₄)₂ (2) with O₂ have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O₂ adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H^¹ = 85.62 kJ·mol^-1, ?S¹ = 19.43 J·mol^-1·K^-1 for compound (1) and ?H^¹ = 97.97 kJ·mol^-1, ?S^¹ = 55.68 J·mol^-1·K^-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH).     

Mineralogical and sink-float studies of Jajarm low-grade bauxite

Jajarm’s bauxite deposits are mainly diasporic, and they have a low mass ratio of Al₂O₃/SiO₂. It is necessary to increase the run-of-mine mass ratio before feeding the material to the Bayer process. Chemical analysis indicated that the low-grade bauxite sample from Jajarm contained 43.9wt% Al₂O₃ and 13.35wt% SiO₂, resulting in a mass ratio of 3.29. According to mineralogical studies, the presence of aluminosilicate minerals such as kaolinite, illite, and quartz was the main reason for the decrease of the mass ratio. Microscopic observations revealed that, with the size reduction from -1000+710 to -38 μm, the liberation degree of diaspore increased from 10% to 60%, and that of aluminosilicates increased from 20% to 85%. Heavy liquids with the densities of 2.8, 3.0, 3.2, and 3.4 g/cm3 were used to evaluate the heavy media separation in three sizes, i.e., -3350+710, -710+212, and -212+125 μm. Laboratory studies confirm that the density of 3.2 g/cm3 can produce the concentrates (in sunk fractions) with recoveries of 89.09%, 91.24%, and 84.68% with the Al₂O₃/SiO₂ mass ratios of 5.03, 5.16, and 5.15 for the -3350+710, -710+212, and -212+125 μm sizes, respectively.     

Up-conversion luminescence of Er^3＋ doped and Er^3＋/Yb^3＋ co-doped YTaO4

The synthesis and up-conversion luminescent properties of YTaO4：Er^3＋ and YTaO4：Er^3＋/Yb^3＋ are reported for the first time. According to the measurement results of up-conversion spectra, Yb^3＋ co-doping can remarkably enhance the green （^2H11/2/^4S3/2→^4I15/2） and red （^4F9/2→^4I15/2） emissions, but depress the infrared emission （^4I9/2→^4I15/2）. With the increase of the Yb^3＋ concentration, the intensity of green emission increases, after that, when the Yb^3＋ concentration increases continuously, the intensity of green emission decreases, while those of the red and infrared emissions increase and decrease alternately. In addition, the up-conversion mechanisms of Er^3＋ doped and Er^3＋/Yb^3＋ co-doped YTaO4 are also discussed. It is found that the transform of up-conversion mechanism from two-step energy transfer to cooperating sensitization takes place when Yb^3＋ concentration is increased up to 12 mol%. With the further increase of Yb^3＋ concentration, the energy-back-transfer gradually becomes the dominant up-conversion mechanism, which results in the quenching of the green emission and slight increasing of the red and infrared emissions.