单质靶溅射制备CZTS薄膜及太阳电池

采用单质靶磁控溅射制备Cu2ZnSnS4 (CZTS)薄膜,研究了薄膜的元素组分、升温速率、硫化温度对薄膜表面平整性以及晶粒尺寸的影响.通过SEM与AFM表征薄膜的表面形貌与表面粗糙度,用EDS检测薄膜的元素组分.所制备的样品的Cu/(Zn+ Sn)、Zn/Sn处于最优范围.通过XRD及Raman检测薄膜的结晶情况以及薄膜中的二次相,经上述测试分析判定CZTS薄膜品质良好.最终制备出以CZTS为吸收层的薄膜太阳电池,并用Ⅰ～V特性检验了CZTS电池性能参数,得到效率为0.83;的CZTS薄膜太阳电池,并通过改进硫化退火工艺将效率提高至1.58;.     

预制层衬底加热对Cu2ZnSnS4薄膜性能的影响

本文采用二步法制备Cu2ZnSnS4(CZTS)薄膜,首先通过真空热蒸发制备CuZnSn (CZT)预制层,其衬底加热温度分别为20℃、50℃、75℃和100℃,然后对所制备的CZT预制层在400℃下硫化60 min,从而制备出CZTS薄膜.利用XRD、Raman、SEM、反射谱和透射谱对所制备的CZTS薄膜进行了表征,实验结果表明,预制层衬底加热温度对CZTS薄膜结构与光学特性有很大影响,在衬底加热50℃时制备预制层硫化后所得CZTS薄膜具有高的结晶度、致密均匀的薄膜表面和最佳1.5 eV光学带隙.此外,与衬底未加热制备预制层在500℃和90 min最佳硫化条件下所制备的高纯CZTS薄膜相比,在50℃预制层衬底加热条件下所制备CZTS薄膜具有更好地结晶质量、更低的硫化温度和更短的硫化时间,这种现象表明衬底加热制备金属预制层利于更高品质CZTS薄膜的制备,可有效的降低硫化温度和缩短硫化时间,当前的研究结果为在低温下实现高质量CZTS薄膜的制备提供了一种有效的途径.     

预制层中Zn和ZnS对CZTS薄膜太阳电池的影响

采用磁控溅射后硫化的方法制备Cu2 ZnSnS4 (CZTS)薄膜,分别用Zn和ZnS作为锌源,在镀钼的钠钙玻璃衬底上以Zn(或ZnS)/Sn/Cu的顺序制备出不同的CZTS薄膜预制层.首先对预制层进行低温合金,然后以硫粉作为硫源进行高温硫化,得到CZTS薄膜.通过X射线衍射仪(XRD)、扫描电镜(SEM)及能谱仪(EDS)分别对所制备薄膜的晶体结构、表面形貌和薄膜组分进行分析表征;并用拉曼光谱表征了CZTS相的纯度.最后用CZTS薄膜制备了太阳电池,发现在预制层中以ZnS作为锌源得到的太阳电池有较高的性能参数,其开路电压:V =651 mV,短路电流密度:Jsc=11.4 mA/cm2,光电转换效率达到2.8;.     

硫化温度-时间曲线对铜锌锡硫薄膜性能的影响

采用溅射法制备含硫预制层,硫化时采用不同的升温速率对经过合金处理的含硫预制层进行退火硫化.通过表征薄膜的表面粗糙度,致密性,均匀性来研究硫化时升温速率对薄膜表面形貌的影响.结果表明当升温速率变慢时,薄膜中的CZTS颗粒逐渐增大,虽然较大的颗粒能减少单位面积内的晶界,但是薄膜的表面粗糙度却随颗粒尺寸的增大而逐渐下降.通过对薄膜的元素组分、晶体结构、相成分进行了检测,确定出薄膜的成分为贫铜富锌的单相锌黄锡矿.再通过测量相应的没有Mo层的CZTS薄膜样品的光电特性来间接的反映拥有Mo层的CZTS薄膜的光电特性.最终制备出结构为SLG/Mo/CZTS/CdS/i-ZnO/AZO/Ni/Al-grid的CZTS薄膜太阳电池,其中转换效率最高的电池为3.60;.     

铜锌锡硫正极全固态薄膜锂离子电池的研究

采用铜锌锡硫(CZTS)四元硫化物材料作为全固态薄膜锂离子电池(TFLB)的正极功能层.通过磁控溅射及硫化工艺制备了CZTS多晶薄膜,并经过组分调控及硫化工艺控制等方案,提高了CZTS正极薄膜的电子导电性.此外,通过引入疏松的微观结构,抑制了由充放电过程中的体积膨胀所导致的容量衰减,提升了TFLB循环性能.所制得的TFLB结构为玻璃/Mo/CZTS/LiPON/Li,首圈放电容量高达200μAh·cm-2 ·μm-1(482 mAh ·g-1),放电平台约为1.1V.     

金属前驱体比例和硫化温度对Cu-Sn-S薄膜特性的影响

使用射频磁控溅射在镀Mo的玻璃基底上制备了Cu/Sn化学计量比为1.4 ～2.0的金属前驱体薄膜.经过400℃、450℃和500 ℃硫化后获得了一系列Cu-Sn-S薄膜.采用X射线衍射、X射线光电子能谱、拉曼光谱、原子力显微镜和紫外可见近红外分光光度计对样品进行了表征.结果表明:硫化温度与前驱体中Cu/Sn化学计量比对Cu-Sn-S薄膜的结构、化学组分和光学性能影响较大.当硫化温度为450℃,前驱体中Cu/Sn化学计量比为1.4∶1时,能得到近乎单一相、四方结构的Cu2SnS3薄膜,光学带隙为1.01 eV.过高的Cu/Sn化学计量比或硫化温度都会导致Cu3SnS4或Cu4SnS4的出现.     

多周期溅射单质靶制备铜锌锡硫薄膜电池

采用多周期磁控溅射单质靶Cu-Sn-Zn制备CZTS薄膜太阳电池.多周期包含两周期和四周期,同时与单周期制备的CZTS薄膜电池作对比.通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)和拉曼光谱仪(Raman)对不同周期得到的CZTS薄膜的晶体性质、表面样貌、化学成分等性质进行分析研究.分析结果显示,多周期制备的CZTS薄膜晶体质量要比单周期的好,表面均匀致密.重要的是四周期溅射制备的CZTS薄膜是研究的最佳实验组.最终把不同周期得到的CZTS薄膜制备成完整的器件结构,得到的太阳电池效率分别是:单周期2.64;,两周期3.01;,四周期3.36;.     

Cu2ZnSnS4纳米片的两步法制备及其光学性能

先后利用化学气相沉积法和液相离子交换法,在FTO导电玻璃基底上两步法制备Cu2ZnSnS4 (CZTS)纳米片,并通过X射线衍射仪(XRD)、拉曼光谱仪(Raman)、扫描电镜(SEM)、透射电镜(TEM)、X射线能谱(EDS)和紫外-可见吸收光谱仪(UV-vis)等表征手段对所得样品的物相结构、微观形貌、化学组分及光学性能进行测试分析.研究结果表明,所得样品为四方晶型CZTS纳米片,对可见光具有良好的全波段吸收,经计算其禁带宽度约1.51 eV.此外,对CZTS纳米片的形成机理进行初步探讨.     

简易溶液法快速制备Cu2ZnSnS4纳米晶工艺研究

采用一种简易溶液法成功快速制备出低成本薄膜太阳能电池用Cu2ZnSnS4(CZTS)纳米晶.探讨合成温度和时间对CZTS纳米晶的结构、形貌、元素比例及光学特性的影响,实现可控的CZTS纳米晶合成.以上特性分别采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量色散谱仪(EDX)、紫外-可见光谱仪(UV-vis)进行表征.结果表明:温度为250℃,时间为1h时可获得锌黄锡矿结构,团聚颗粒约为200～500 nm,化学计量比约为Cu∶ Zn∶ Sn∶S=2.17∶ 1∶1.23∶4.69,禁带宽度为1.5 eV的纳米晶,适合印刷法制备CZTS薄膜太阳能电池吸收层.     

GeSe基薄膜太阳电池模拟研究

硫化亚锗(GeSe)具有合适的禁带宽度、高的吸收系数和高的载流子迁移率等优异的光电特性,且组分简单、低毒和储量丰富,特别适合作为光伏吸收材料。本文基于新型太阳电池吸收层材料GeSe构筑了结构为金属栅线/AZO/i-ZnO/CdS/GeSe/Mo/玻璃的薄膜太阳电池,分别模拟分析了缓冲层和吸收层的厚度、掺杂浓度,以及吸收层体缺陷密度对器件性能的影响。经过优化CdS缓冲层厚度和掺杂浓度以及GeSe吸收层厚度和掺杂浓度,器件获得高达27.59%的转换效率。这些结果表明GeSe基薄膜太阳电池有成为高效光伏器件的潜力。     

A review of measurement of thermophysical properties of silicon melt

Measurements of thermophysical properties of Si melt and supplementary study of X-ray scattering/diffraction by the authors' group were reviewed. The values obtained differed variously from those of literature. Density was 2–3% larger, surface tension 20–30% smaller, viscosity up to 40% larger, electrical conductivity 8% smaller, spectral emissivity more or less in good agreement with literature values, and thermal diffusivity a few percent larger. An anomalous density jump was found near the melting point. Surface tension and viscosity also showed anomaly. A strange time-dependent change of density was observed over 3 h after melting. X-ray analyses suggested a slight change in local atom ordering, but showed no sign of cluster formation. An addition of 0.1 at% gallium caused the density jump to disappear, while that of boron caused no change. An EXAFS study of the former melt indicated a strong interaction between Ga and Si atoms as if molecules of GaSi₃ existed. The implications of the measured properties are a possibility of soft-turbulence in an Si melt in a relatively large crucible, a more complicated manner of intake of oxygen depleted molten Si from the free surface region to underneath the growing crystal, and a relaxation of the melt after melting arising from trapped gas species.     

Effect of alumina on enthalpy of mixing of mixed alkali silicate glasses

The enthalpy of mixing of mixed alkali (Na₂O and K₂O) silicate glasses containing various concentrations of alumina was determined using an ion-exchange equilibrium method. For glasses with a constant alkali concentration, the enthalpy of mixing was found to become less negative with alumina addition. Consistent with our previous results on the enthalpy of mixing of alumina-free mixed alkali silicate glasses, the magnitude of enthalpy of mixing exhibited a good correlation with the molar volume mismatch of the corresponding two single alkali glasses as well as with the extent of conductivity mixed alkali effect, e.g. excess activation energy of conductivity, ΔE. The reduction of the magnitude of the enthalpy of mixing with alumina addition can be attributed to the reduction of non-bridging oxygen and ionic field strength. Combining the present results with results obtained earlier, the magnitude of the enthalpy of mixing for all mixed alkali (Na₂O and K₂O) silicate glasses with and without alumina was expressed by a simple function of a modified Tobolsky parameter, which takes into account the alkali concentration and the difference in cation-to-effective anion distances. The enthalpy of mixing data of the mixed alkali glasses was then compared with reported experimental data on the conductivity of mixed alkali aluminosilicate glasses. What appears to be conflicting experimental data can be understood in terms of the magnitude of the enthalpy of mixing and we can conclude that the mixed alkali effect is closely correlated with the negative enthalpy of mixing.     

Mesomorphism Dependence on the Position of Substitution of a Pair of Esters

A novel homologous series of ethylene derivatives of thermotropic liquid crystals has been synthesized. The methoxy to octyloxy derivatives are nematogenic, the decyloxy to tetradecyloxy derivatives are smectogenic, in addition to nematogenic, and the hexadecyloxy homologue is smectogenic only. All the members of the series are enantiotropically mesogenic. Thermotropic behavior was determined by an optical polarizing microscope equipped with a heating stage and Differential Scanning Calorimetry (DSC) study. Analytical and spectral data confirm the molecular structures of homologues (infrared, nuclear magnetic resonance, mass spectra, X-ray, and DSC data). Textures of the nematic phase are threaded or Schlieren and that of smectic phase are focal conic fan-shaped of smectic A or C. Transition curves of the phase diagram behave in a normal manner except one or two deviations from the normal trend. The mesophase range (Sm+N) varies from 3°C to 44°C. The average thermal stability for smectic is 93°C and that for nematic 117.4°C. The LC behavior of the novel series is compared with a structurally similar known series.     

原位氮化法制备TiN纳米粉体

用溶胶凝胶法合成的纳米TiO2粉体作为原料,将该粉体在氨气中进行原位氮化制备了TiN纳米粉体.用XRD,TEM,化学分析等手段对合成的TiN纳米粉体的物相组成、形貌、成分进行了分析.实验分析表明:在1000℃和1100℃下分别氮化5h,可以制备粒径大约为40nm和80nm的TiN粉体,其TiN的含量分别为95.40;和98.37;;而在1000℃条件下氮化时间减少到2h时,TiN的含量仅为58.36;.氮化温度和氮化时间是合成纳米TiN的重要因素,提高合成温度和延长氮化时间均可形成纯度较高的TiN纳米粉体,但延长氮化时间更有利于获得粒径小的氮化钛粉体.     

立方晶系晶体本征铁弹相变序参量的选取

在本征铁弹相变的软模理论的基础上,依据弹性本构关系和居里原理,给出了立方晶系晶体所有可能的自发应变的种类,研究了立方晶系晶体本征铁弹相变序参量的选取问题.以Th群和Oh群为例,阐明了不同类的序参量导致晶体对称性变化相同的的原因,提出了该情况下序参量选取的“就少不就多”的原则.得到了发生本征铁弹相变时所有可能的序参量及晶体的对称性的变化.     

On the influence of structural features of DNA on the possibility of metabolic transfer of electrons

Abstract

A fragment of a DNA molecule is considered as one of the channels of metabolic electron transfer. The heterogeneity of the complementary chains is effectively taken into account. This made it possible to find the speed of the electron injected into the DNA conduction band and the current density that it creates. Estimates of electron mobility in nucleic acid chains are made. They were an order of magnitude smaller than that of typical semiconductors. For the specific conductivity of nucleic acid chains, estimates provide a conductivity of one to two orders of magnitude lower than in graphite.     

Features of transformations in REE-containing systems of nitrate precursors in preparatory processes of formation of multifunctional oxide materials

Abstract

The complex study provides a reliable idea of ??the trends in the joint behavior of structural components in the water-salt systems of nitrate precursors of REE, alkaline, alkaline earth metals in the preparatory stages of the processes of forming multicomponent oxide polyfunctional materials on their basis with thermal activation. Stages of such transformations are revealed; The regularities of complex and phase formation in systems and factors influencing them are determined; A number of physicochemical properties of the intermediate phases formed - coordination lanthanides nitrates: their composition, types of compounds, atomic-crystalline structure, regularities of transformations during heat treatment were studied.     

Growth and characterization of semicarbazone of cyclohexanone

A new organic single crystal of semicarbazone of cyclohexanone (SCCH) has been synthesized and grown as a bulk single crystal by low temperature solution growth technique for the first time in the literature. The grown crystal has been confirmed by X‐ray diffraction and proton nuclear magnetic resonance spectral analyses and also characterized by FT‐ir and FT‐Raman studies. Thermal properties of the grown crystals were studied by thermogravimetric and differential thermal analyses. Optical transmittance was studied by ultraviolet‐visible spectrum and the second harmonic generation property was tested by using Q switched Nd: YAG laser as a source. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of density of states on optical properties of GaSe thin film

A systematic investigation on the effect of substrate temperature on the structure, optical absorption and density of states of vacuum evaporated gallium monoselenide (GaSe) thin films is reported. The X‐ray diffraction analysis shows an occurrence of amorphous to polycrystalline transformation in the films deposited at higher‐temperature substrates (573K). The compositional analysis is made with Auger Electron Spectroscopy (AES). The thickness of the film (175nm) is measured by a multiple beam interferometery. Optical characteristics of the GaSe sample have been analyzed using spectrophotometer in the photon energy range of 1.0 ‐ 4 eV. The absorption mechanism has been recognized and the allowed indirect as well as forbidden direct transitions have been found. As‐deposited films show two indirect and allowed transitions due to spin‐orbit splitting of the valence band, as reported here for the first time. Low field conduction have enabled us to determine the density of states in amorphous and poly‐GaSe films. The amorphous and polycrystalline GaSe thin films have localized states density values of N (E_F) = 1.686 × 10¹⁷ cm^‐3 eV^‐1 and 1.257 × 10¹⁵ cm^‐3 eV^‐1 respectively. The experimental results are interpreted in terms of variations in the density of localized states due to progressive decrease of the unsaturated bonds during deposition. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

电子显微分析在表征纳米晶体化学组分中的应用

纳米材料的化学组分及含量影响其光、电、声、热、磁等物理性能,电子显微分析是表征纳米晶体化学组分的重要方法之一.本文综述了X-射线能谱(EDS)、X-射线波谱(WDS)、电子能量损失谱(EELS)和选区电子衍射(SAED)等现代电子显微分析技术在表征纳米晶体化学组分、形貌、尺寸和结构等方面的应用及其研究进展,并比较了这些分析方法存在的差异,提出了其应用中存在的不足及今后的研发方向.