高光敏性酞菁氧钛及光电器件制备工艺研究

研究了高光敏性TiOPc及其光导器件的制备工艺.研究结果表明,以邻二氯苯/水为晶型调节剂,经减压加热干燥可制得高光敏性Y-TiOPc;以Y-TiOPc为载流子产生材料,以2丁酮为分散剂,在m (TiOPc):m (PVB)=1:1时制得光电器件载流子产生层,此时充电电位V0,残余电势Vr, 表面电压衰减到一半时所需的能量 E1/2分别为720 V,20 V,072lx.s,光导器件的光电导性能最好.     

酞菁氧钛的光敏性研究

以邻二氯苯和丁醇的混合溶液为晶型调节剂对酞菁氧钛的晶型进行调节,研究了混合液中丁醇的体积含量对酞菁氧钛光电导性的影响。光电导性测试结果表明,晶型调节剂中丁醇的体积含量对酞菁氧钛的光电导性有较大影响,随丁醇体积含量的增加,酞菁氧钛的光电导性越来越好。当采用100％的丁醇进行晶型转换时,用得到的光敏性TiOPc制备有机光导器件,V0=1040V,E1／2=1．11x．s。     

Zn掺杂TiO2薄膜紫外探测器及其光电性能研究

采用射频磁控溅射的方法制备Zn掺杂TiO2薄膜,用XRD、SEM和UV-Vis分别表征TiO2薄膜的晶体结构、表面形貌及其紫外-可见光吸收谱.并用此材料制备Au/TiO2/An结构MSM光电导型薄膜紫外光探测器,研究其光电特性.实验结果表明,Zn掺杂TiO2紫外探测器在250 nm、5 V偏压紫外光照下光电流约为500μA,其响应度为100 A/W,平均暗电流约为0.5μA;由于ZnO/TiO2复合薄膜之间的费米能级不同而形成的内建电场作用,减少了产生的光生电子与空穴的复合,得到较强的光电流.且其光响应的上升迟豫时间约为22 s,下降响应时间约为80 s;响应时间较长是由于广泛分布于薄膜中的缺陷而造成的.结果表明Zn掺杂TiO2可作为一种良好的紫外探测材料.     

超稳定有机光导材料分散体系的构建及高光敏单层光导器件

将载流子产生与传输功能集成到一层的高性能正电性薄膜器件是新型激光有机光导体的发展趋势。由于成膜树脂、传输材料分子和载流子产生材料粒子之间的相互作用,使得成膜之前的分散体系极易团聚而产生沉降现象,导致光导器件的性能劣化。本文以聚苯乙烯-丙烯酰胺(PSAM)、聚苯乙烯(PS)、聚乙烯吡咯烷酮(PVP)和硬酯酸酰胺(SR)分别在二氯乙烷中对Y-酞菁氧钛(Y-TiOPc)粒子进行表面处理,获得稳定的分散体系,然后再与溶解空穴及电子传输材料的聚碳酸酯二氯乙烷溶液混合得到有机光导材料分散液。通过测试Y-TiOPc的粒径、ξ电位、光透过率和反射率,以及原子力显微成像分析等表征分散体系的稳定性。结果表明,采用该方法可获得长期稳定的PSAM@Y-TiOPc/TPD-m-TPD/DMDBQ/PC有机光导材料分散体系,制备的单层正电性有机光导器件具有优异的光导性能,V0=656.72V,E1/2=0.16μJ/cm2,Rd=29.10V/s,Vr=71.47V。     

染料敏化太阳能电池中CuO/TiO2薄膜制备及应用

采用普通直流电沉积和超声直流电沉积制备Cu∕TiO2纳米管阵列∕Ti基复合薄膜,而后在NaOH溶液中用电氧化的方法将Cu单质氧化成CuO,制备了CuO∕TiO2纳米管阵列∕Ti基复合薄膜。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对两种复合薄膜电极的形貌和结构进行了表征,详细考察了电镀工艺参数(电流密度)和超声波对复合薄膜形貌的影响。同时通过稳态光电响应技术对复合薄膜电极组成的染料敏华太阳能电池(DSSC)的光电性能进行了研究,结果表明:通过普通直流电沉积在工艺参数(3mA/cm2、5min)处制备的复合薄膜组装的DSSC具有该体系下的最佳光电性能(Jsc=9.00mA/cm2、Voc=0.664V、FF=0.512、η=3.06%);在同等条件下通过超声辅助直流电沉积制备的复合薄膜组装的DSSC的最佳光电性能(Jsc=15.50mA/cm2、Voc=0.688V、FF=0.505、η=5.39%)出现在工艺参数为(6mA/cm2、5min)处。对比可知超声条件下的光电性能较好,且最佳光电性能工艺参数发生了后移。     

溶胶-凝胶法制备AZO薄膜及Al掺杂机理的研究

采用溶胶-凝胶法和浸渍提拉法成功制备了Al掺杂ZnO薄膜(以下简称AZO薄膜)。用X射线衍射仪(XRD)、场发射扫描电镜(FE-SEM)、分光光度计、霍尔(Hall)测量仪,分别研究了不同Al的掺杂浓度对薄膜的结晶性能、微观形貌和光电性能的影响,探讨了Al的掺杂机理。结果表明,Al的掺杂存在最佳值,当Al掺杂摩尔浓度为5%时,AZO薄膜的结晶性能、微观形貌和光电性能最佳,其透光率在80%以上,电阻率为2.1×102Ω·cm,霍尔迁移率为0.23cm2/V·s,载流子浓度为7.81×1014cm-3。     

酞菁铜/氧化钛纳米复合薄膜的制备及其光导性能的研究

通过电化学阳极氧化法在Ti片上制备了氧化钛(TiO2)纳米管阵列.用这种高度有序的阵列结构作为模板,利用电泳沉积的方法在模板表面沉积了一种有机半导体材料酞菁铜(CuPc),从而得到了CuPc/TiO2有机/无机纳米复合结构.通过场发射扫描电镜(FESEM),透射电镜(TEM)等手段对这种复合结构的表面形貌及结构进行了表征.能谱数据证实了复合结构中有机物的存在.此外,CuPc薄膜的形貌和结构可以通过改变电泳沉积参数(如沉积时间和电压)进行调控,从而得到相应的纳米晶、纳米线和微米线薄膜.用该复合薄膜作为载流子发生层制备的双层光导体的光导性能测试结果表明,与复合前的氧化钛薄膜相比,该复合薄膜的光敏性有明显的提高.     

Synthesis and photoconductivity of nanosized phthalocyanine

Functional phthalocyanine （Pc） compounds of H2Pc, TiOPc, FePc and CIAIPc were synthesized with a yield of 46.7%, 91.2%, 37.4% and 34.0%, respectively. Nanosized TiOPc was synthesized via a one-step sol-gel method and effects of surfactant doses, nucleation temperature on TiOPc particle size and photoconductivity were investigated. When re（PEG）： m（TiOPc） was 0.1 and nucleation temperature was 0℃, the as-obtained TiOPc had the smallest particle size and largest specific surface area, which were 60 nm and 83m^2/g, respectively. TiOPc synthesized under these conditions also exhibits excellent photoconductivity with charging potential V0, dark decay speed Rd and energy for half-discharging of potential E1/2 being 1160 V, 30 V/s and 0.6 1x.s, respectively.     

复合相变储冷材料的制备及性能研究

以十二烷基苯磺酸钠(SDBS)作为分散剂,多层石墨烯、TiO2/石墨烯(m(TiO2):m(石墨烯)=25∶75)和TiO2颗粒作为导热添加剂,加入到二元复合有机储冷材料中(m(壬酸):m(葵醇)=60:40),制备了复合相变储冷材料。通过吸光度、DSC和热导率测试等手段,对复合相变储冷材料的稳定性、相变温度、相变潜热及热导率进行了评价分析。结果表明,分散剂和导热添加剂的加入,对储冷材料的相变温度和相变潜热影响不大,但对热导率影响较大。当分散剂SDBS浓度为0.2 g/L,导热添加剂(分别为TiO2/石墨烯和TiO2颗粒)浓度为0.5 g/L时,复合相变储冷材料具有较好的稳定性,其热导率分别为为0.2211和0.2096 W/(m·K),相比没有加入任何导热添加剂的储冷材料的热导率(0.1738 W/(m·K)),分别提高了27.22%和20.61%;当分散剂SDBS浓度为0.3 g/L,导热添加剂多层石墨烯浓度为0.3 g/L时,复合相变储冷材料处于稳定状态,其热导率为0.2268 W/(m·K),相比0.1738 W/(m·K),提高了30.49%。由此可知,多层石墨烯可以更有效地增加复合相变储冷材料的热导率,这主要是由于石墨烯具有非常高的比表面积,有利于复合材料更加均匀地分散以及形成更加完善的网格结构,从而有效增加复合相变储冷材料的稳定性及热导率。选用多层石墨烯为导热添加剂(0.3 g/L),SDBS为分散剂(0.3 g/L),可以制备出体系最稳定、热导率最高的复合相变储冷材料。     

TiO2/活性炭复合纳米纤维膜的制备及表征

在聚丙烯腈(PAN)、N,N-二甲基甲酰胺(DMF)体系中加入钛酸四丁脂水解溶胶,通过静电纺丝技术得到纳米纤维膜,经预氧化、炭化、活化制备出TiO2/活性炭复合纳米纤维膜。采用扫描电子显微镜、X射线能谱、热分析、傅里叶红外光谱、X射线衍射以及测定Zeta电位和表面接触角等手段对TiO2/活性炭复合纳米纤维膜进行表征。结果表明,当V(PAN)∶V(DMF)∶V(Ti(OH)4)溶胶=3∶17∶3时,可制得纤维直径为600～700nm的TiO2/活性炭复合纳米纤维膜。纳米TiO2在TiO2/活性炭复合纳米纤维膜中分布均匀,晶型结构易于控制;TiO2/活性炭复合纳米纤维膜有较强的光催化活性和吸附活性,可以作为环境功能材料使用。     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Anomalous Hall Effect in Sn1?x?yMnxEuyTe and Sn1?x?yMnxEryTe Mixed Crystals

The Anomalous Hall Effect (AHE) was investigated in IV–VI ferromagnetic semimagnetic semiconductors of Sn_1–x Mn _x Te codoped with either Eu or Er. The analysis of experimental data is as follows. Hall resistivity and magnetization showed that AHE coefficient R _s depends on temperature and its value decreases with thetemperature increase. We observe that above ferromagnet–paramagnet transition temperature R _s changes sign. We discuss the possible physical mechanisms responsible for observed temperature dependence of R _s , particularly change of the sign.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.     

Tc trend in high-Tc superconductors

In our previous works, we have shown that most existing ceramic superconductors can be considered to be built of superconductor-semiconductor composite and we have estimated the change in phonon spectrum of the intrinsic superconductor unit if a semiconductor unit is attached to it. Moreover, the proximity effect under the size quantization condition has been examined in the superconductor-semiconductor composite. Each of the stated effects by itself could causeT _c enhancement in general as more semiconductor blocks are added to the system. We extend our study in this paper to analyze the combined actions of phonon spectral change and proximity effect without size quantization condition onT _c variation in members of the Tl₁ series of high-T _c superconductors. Our results indicate that an optimumT _c is obtained if the stated effects are included in the idealized unit cells of the superconductors made up of a superconductor-semiconductor array.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Effect of pressure onTc in La2-xBaxCuO4 withx=0.125

The superconducting transition temperature,T _c , of La_2–x Ba _x CuO₄ has been measured under high pressure up to 8 GPa.T _c is found to change drastically at the pressure where the structural phase transition takes place. This finding clearly indicates that there exists an intimate relation between the crystal structure and superconductivity.