Pechini法制备TiO_2薄膜及其在染料敏化太阳电池中的应用

用Pechini法在FTO导电玻璃上制备不同厚度的TiO2薄膜,并组装成染料敏化太阳能电池。XRD结果表明,在450℃退火1h得到了主相为锐钛矿的TiO2。SEM结果表明,TiO2薄膜表面疏松多孔,粒径均匀,厚度在6~15μm。紫外-可见光谱分析表明,TiO2薄膜染料的吸附量随薄膜厚度的增加而增加。光电性能研究表明,在0.005W/cm2的弱光照下,膜1(厚6μm)和膜2(厚15μm)光阳极的光电转换效率分别为6.85%和11.83%;在0.1 W/cm2的模拟标准太阳光照下,膜1和膜2光阳极的光电转换效率分别为1.72%和2.39%。     

Controllable synthesis of quasi-spherelike ZnO hierarchical nanostructures and performance of their dye-sensitized solar cells

Hierarchical zinc oxide (ZnO) quasi-spheres consisting of nanoparticles with diameter of about 20 nm were synthesized via a one-pot reaction. The size of ZnO quasi-spheres is easily tunable from 80 nm to 3 μm by varying the type of zinc source and its concentration. The three samples 1-3 with the diameter of 80-180 nm, 300-600 nm and 1.2-2.9 μm were selected for fabricating dyesensitized solar cells (DSSCs) and their photovoltaic properties were measured. The results demonstrate that DSSCs fabricated by sample 2 with the diameter within the wavelength of visible light obtain the highest short-circuit current density and over light conversion efficiency, due to resonant scattering increasing the photon absorption.     

两种形貌FeS2的合成及其在染料敏化太阳能电池上的应用

通过对比FeS2颗粒两种形貌的催化活性及在染料敏化太阳能电池(DSSCs)上的表现,选择出性能更高的FeS2颗粒.通过水热法和热注入法合成了立方体和球状高纯度FeS2,将FeS2制备成对电极(CEs)并组装在DSSCs上.通过测试电池的光电转化效率及对电极的催化活性,发现球状FeS2颗粒有更高的催化活性,基于球状FeS2 CEs的电池也获得了更高的光电转化效率.在100 mW/cm2 (AM 1.5)强度的模拟光源下,基于立方体和球状高纯度FeS2 CEs的DSSCs分别获得了高达4.55％和5.69％的光电转化效率.     

Gallium-oxide films obtained by thermal evaporation

The current-voltage (I–V), capacitance-voltage (C–V), and conductance-voltage (G–V) characteristics of metal/Ga _x O _y /GaAs/metal structures are investigated. Gallium-oxide films with a thickness of 150–170 nm are deposited by the thermal evaporation of Ga₂O₃ powder onto n-type GaAs substrates with the donor concentration N _d = 2 × 10¹⁶ cm^?3. Treatment of the Ga _x O _y films in oxygen plasma causes a decrease in both the forward and reverse currents and a shift of the C–V and G–V curves to higher positive voltages. The Fermi level at the insulator/semiconductor interface in the structures under study is unpinned. The density of states at the Ga _x O _y /GaAs interface is N _t = (2–6) × 10¹² eV^?1 cm^?2.     

ZnO薄膜对于CdTe太阳电池的影响*

通过直流磁控溅射法在ITO薄膜上沉积的ZnO薄膜可以作为CdTe太阳电池的高阻层。通过XRD,可见-红外可见光谱仪和四探针法分析了制备薄膜的结构,光学和电学性质。通过紫外光电子能谱和X射线光电子能谱深度刻蚀法分析了ITO/ZnO和ZnO/CdS薄膜的界面性质。结果表明：ZnO 作为高阻层有良好的光学和电学性质。ZnO 薄膜降低了ITO和CdS之间的势垒。 制备出来电池有ZnO（没有ZnO）的能量转换效率和量子效率是12.77% (8.9%) 和 >90% (79%)。 进一步,通过AMPS-1D模拟分析了ZnO薄膜厚度对于CdTe太阳电池的影响。     

Grain size effect of nanocrystalline ZnO on characteristics of dye-sensitized solar cells

In this study, we demonstrate a dye-sensitized solar cells (DSSCs) was made by using two different grain sizes of nanocrystalline ZnO (nc-ZnO) as the photoelectrodes of the cells. It can be seen that the efficiency of this new type of solar cells obviously varied as the size and morphology of ZnO nanostructures. The short-circuit photocurrent, fill factor, and power conversion efficiency are enhanced while the smaller nc-ZnO was utilized in such a device.     

氧化锌纳米线在FTO玻璃上的合成生长及其在染料敏化太阳电池中的应用

Long and well-aligned ZnO nanowires were hydrothermally synthesized on FTO glass based on a ZnO seed layer which was prepared by spin-coating and annealing techniques.The effect of the growth solution refreshment on the morphology of ZnO nanowires was investigated and the possible mechanism was discussed.After refreshing the growth solution for 5 cycles,ZnO nanowires of ~ 120 nm in diameter and ~ 20 /μm in length were obtained.The prepared ZnO nanowires were used as photoelectrodes in dye-sensitized solar cells(DSSCs),showing excellent photovoltaic performance.With the increase of growth cycles of ZnO nanowires,the photocurrent of DSSCs increased obviously due to the increased dye loading on the surface of ZnO nanowires.The results indicated that the lone and well-aligned ZnO nanowires are promising for DSSCs application.     

Synthesis and Raman spectra of hammer-shaped ZnO nanostructures via thermal evaporation growth

Hammer-shaped ZnO nanostructures were synthesized on silicon substrate via a simple thermal evaporation process without catalysts or additives. Scanning electron microscopy results shows that ordered ZnO nanohammers grow from the Si substrate. Transmission electron microscopy and selected area electron diffraction analysis indicate that a single nanohammer is a single crystal and grows along (0001) direction. X-ray diffraction patterns for prepared samples are consistent with a wurtzite ZnO structure. The effect of temperature on Raman scattering of single crystal ZnO nanohammers in the temperature range from 83 to 523 K was determined. Temperature-dependent Raman spectra of E₂(high frequency or hf) exhibit phonon frequency redshift and linewidth broadening with increasing temperature, which can be explained by a model taking into account contributions of thermal expansion and anharmonic phonon processes. Results show that decay into three phonons is the probable channel for the E₂(hf) mode.     

Highly conducting and transparent Ga2O3 doped ZnO thin films prepared by thermal evaporation method

Amorphous zinc oxide thin films are obtained by thermally evaporating pure zinc oxide powder. Films obtained have an excellent conductivity of 90 ??^?1 cm^?1 with transparency of up to 90% in the visible region. On doping with gallium oxide a great improvement in the conductivity of up to 8.7 × 10³ ??^?1 cm^?1 is observed and the optical band gap of the films is decreased from 3.25 to 3.2 eV, retaining the transparency. Measurements of activation energy show that the doped ZnO film has one donor level at 68 meV and other at 26 meV bellow the conduction band.     

Synthesis of PbS:ZnO nanotrees by thermal evaporation:morphological, structural and optical properties

Nanotrees ZnO films are synthesized by thermal evaporation method on silicon and glass substrates. PbS powder (5 wt%) is used to obtain the nanostructure and growth modifications. ZnO films are compared with non-doped ones (ZnO film was dense structure without nanotrees). The deposited PbS:ZnO films exhibit polycrystalline orientation using X-ray diffraction (XRD), but the films without doping was less crystalline quality. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology. SEM images (surface and cross section) was confirmed the nanotrees form for doped ZnO film. Energy dispersive X-ray detector (EDX) was used to verify the composition of prepared films. Ultraviolet-visible (UV-Vis), photoluminescence (PL) and micro Raman techniques were used to investigate the optical properties. The PL spectra intensities were found to increase for PbS:ZnO nanotrees. Up to our knowledge, no work has been published regarding the obtained ZnO nanotrees using PbS as dopant via simple thermal evaporation method.     

染料敏化太阳能电池数值模拟的研究进展

染料敏化太阳能电池以潜在的高光电转换效率、简单的制作工艺和廉价的生产成本而为人们所重视,现在进行实验研究的同时,理论仿真的研究也取得了一定的成果.现主要介绍了染料敏化太阳能电池从经典的单区域模型到双区域、三区域的模型的仿真发展情况.分别介绍了仿真的基本机理,国内外研究现状,并对其未来的发展前景进行了展望.     

硫化钴镍的制备及其作染料敏化太阳能电池对电极的性能研究

不同温度下通过两步水热法在氟掺杂氧化锡导电玻璃上制备了钴镍双金属硫化物对电极。并通过X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、循环伏安测试(CV)、电化学阻抗谱分析(EIS)以及光电流密度-电压特性曲线(J-V)分别研究了其物相、表面化学元素组成及其化学状态、表面形貌、电催化活性和光电转化性能。结果表明该硫化物为直立片状的NiCo_2S_4,90℃制备的对电极具有较高的电催化活性,其电池的光电转化效率达到了与Pt电极电池效率(6.02%)相比拟的值(5.74%)。而120℃制备的对电极虽然具有更大比表面积,但其膜太厚,显著增加了电解质的能斯特扩散电阻,导致其电池效率偏低。     

Preparation of titanium dioxide-double-wailed carbon nanotubes and its application in flexible dye-sensitized solar cells

Titanium dioxide-double-walled carbon nanotubes (TiO2-DWCNTs) with DWCNTs/TiO2 of 20 wt.％ is prepared by a conventional sol-gel method.Doping the TiO2-DWCNTs in TiO2 photoanode,a flexible dyesensitized...     

Electrolyte-dependent photovoltaic responses in dye-sensitized solar cells

Promoted by the growing concerns about the worldwide energy demand and global warming, dyesensitized solar cells (DSSCs) are currently attracting worldwide scientific and technological interest because of their high energy conversion efficiency and simple fabrication process. Considering long-terms stability and practice applications, growing attentions have been paid to non-volatile, 3-methoxyproprionitrile (MPN)-based electrolyte, ionic liquids (ILs) electrolyte, as well as quasi-solid state electrolyte. In this present review, recent progress in electrolyte for DSSCs made by our group are summarized,including component-optimization of the non-volatile electrolyte, the fluidity-dependent charge transport mechanism in the binary IL electrolytes as well as the structure dominance of the employed ILs. Furthermore,progress on the quasi-solid state electrolyte based on inorganic nanomaterials as gelators in our group has also been outlined.     

Electron transportation and optical properties of microstructure TiO2 films: applied in dye-sensitized solar cells

Micro-structure of TiO2 films in dye-sensitized solar cells (DSSCs) can affect light absorption and electron transportation that impact on the characteristics of currentvoltage (J-V). In this paper, films with different surface area, pore size and porosity were obtained by adding different ratio of ethyl cellulose (Ec-S) to pastes, and a photo-electric conversion efficiency (η) of 7.55% with a showed that film with this optimum ratio had the most suitable pore size and surface area for good properties of photovoltaic, which had a low reflectivity and high transmission rate, and the efficiency of light utilization was improved. Moreover, measurements by intensitymodulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS)implied that the electron transport time (rd) increased as the content of Ec-S increased, which was related to the larger surface area. Results of steady-state cyclic voltammetry indicated that diffusion-limited current density (Jlim) of I3-;in TiO2 film increased with its porosity, which revealed that the transportation ofredox mediators in the electrolyte was speeded up.     

Gettering by heat thermal processing: application in crystalline silicon solar cells

The aim of this work is to getter unwanted impurities from solar grade crystalline silicon (Si) wafers and then to enhance their electronic properties. This was done by forming a sacrificial porous silicon (PS) layer on both sides of the Si wafers and by performing infrared (IR) thermal annealing treatments (at around 950 °C) in a SiCl₄/N₂ controlled atmosphere. The process allows concentrating unwanted impurities in the PS layer and near the PS/silicon interface. These treatments reduce the resistivity by about two orders of magnitude at a depth of about 40 μm and improve the minority carrier diffusion length from 75 to 210 μm. This gettering method was also tested on silicon wafers where grooved fingers and back contacts were achieved using a chemical vapor etching (CVE) method. Front buried metallic contacts and small holes for local back surface field were then achieved after the gettering stage in order to realize silicon solar cells. It was shown that the photovoltaic parameters of gettered silicon solar cells were improved as regard to ungettered ones.     

Delaying the degradation caused by water of dye-sensitized solar cells

A pure water electrolyte was fabricated and tested in printable flexible dye sensitized solar cells. The outdoor performance in highly humid condition shows significant degradation caused by water, which was rectified by introducing hydrophilic silica nanoparticles thus successfully delaying the degradation by three-fold.     

Studies of high-efficient and low-cost dye-sensitized solar cells

Dye-sensitized solar cell (DSSC) is a new type of photoelectric device. To commercialize DSSC successfully, it is necessary to further improve the efficiency of energy conversion and reduce its cost. Nitrogen-doped (N-doped) TiO2 photoanode, the carbon counter electrode (CE), and a new type of hybrid photoanode were investigated in this study. The conversion efficiency of the DSSC reached by 10.10% as the DSSC was fabricated with the N-doped photoanode, and this efficiency is much higher than that of the undoped-DSSC with 8.90%; as the low-cost carbon was used as CE, the efficiency of the DSSC was 7.50%, it was as samilar as that of Pt CE (7.47%); the hybrid DSSC with multilayer photoanode by the film-transfer technique achieved a panchromatic response and a superposed short circuit current density (Jsc) by using two complementary dyes.     

ZnS thin films deposition by thermal evaporation for photovoltaic applications

ZnS thin films were deposited on a glass substrate by thermal evaporation from millimetric crystals of ZnS.The structural, compositional and optical properties of the films are studied by X-ray diffraction, SEM microscopy, and UV-VIS spectroscopy.The obtained results show that the films are pin hole free and have a cubic zinc blend structure with (111) preferential orientation.The estimated optical band gap is 3.5 eV and the refractive index in the visible wavelength ranges from 2.5 to 1.8.The good cubic structure obtained for thin layers enabled us to conclude that the prepared ZnS films may have application as buffer layer in replacement of the harmful CdS in CIGS thin film solar cells or as an antireflection coating in silicon-based solar cells.