Dye-sensitized solar cells based on ordered titanate nanotube films fabricated by electrophoretic deposition method

Dye-sensitized solar cells (DSSCs) are fabricated based on ordered titanate nanotube (TNT) films obtained by electrophoretic deposition (EPD) method. Calcination temperatures show a great influence on the performance of TNT solar cells. At 300 °C, the cells exhibit very low photo-electric conversion efficiency. At 400 °C, the efficiency obviously increases. At 600 °C, the cells show the highest efficiency, which is higher than the efficiency of the cells made from commercial-grade Degussa P25 TiO₂ nanoparticles (P25).     

Dye-sensitized TiO2 Solid Solar Cell Using Poly （4-vinylphenyloxy-methyltriphenylamine） as Hole Transport Material

A dye-sensitized TiO2 solid solar cell, which contains poly(4-vinylphenyloxy-methyltriphenylamine) in hole transport layer (HTL) doped with LiSCN and methyl-hexyl-imidazolium iodide (MHImI), was oreoared. The solar cell shows that the conversion efficiency is 0.59%, Jsc is 3.03mA/cm^2, and Voc is 0.53V at 1 sun light intensity.     

Synthesis of nano-TiO2 assisted by diethylene glycol for use in high efficiency dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSSCs) consisting of anatase TiO_2 nanoparticles that were synthesized via a hydrothermal method was studied.The synthesized TiO_2 nanoparticles were characterized by X-ray diffraction(XRD),nitrogen sorption analysis,scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM),and UV-vis spectroscopy.Then the J-Vcurve,electrochemical impedance spectroscopy(EIS),and open-circuit voltage decay(OCVD) measurement were applied to evaluate the photovoltaic performance of DSSCs.Compared with the commercial TiO_2nanoparticles(P25),the synthesized-TiO_2 nanoparticles showed better performance.By adding diethylene glycol(DEG) before the hydrothermal process,the synthesized TiO_2 nanoparticles(hereafter referred to as TiO_2-DEG particles) shows narrower size distribution,larger specific surface area,higher crystallinity,and less surface defects than TiO_2(DEG free) particles.The analysis of photovoltaic properties of DSSCs based on TiO_2-DEG particles showed that the recombination of electron-hole pairs was decreased and the trapping of carries in grain boundaries restrained.It was believed that the photoelectrode fabricated with the as-prepared TiO_2 nanoparticles improved the loading amount of dye sensitizers(N719).and enhanced the photocurrent of the DSSCs.As a result,the TiO_2-DEG particle based cells achieved a photo-to-electricity conversion efficiency(η) of 7.90%,which is higher than 7.53%for the cell based on TiO2(DEG free) and 6.59%for the one fabricated with P25.     

Photosensitization of TiO2 nanoparticulate thin film electrodes by CdS nanoparticles

Surface photovoltage spectra (SPS) measurements of TiO₂ show that a large surface state density is present on the TiO₂ nanoparticles and these surface states can be efficiently decreased by sensitization using CdS nanoparticles as well as by suitable heat treatment. The photoelectrochemical behavior of the bare TiO₂ thin film indicates that the mechanism of photoelectron transport is controlled by the trapping/detrapping properties of surface states within the thin films. The slow photocurrent response upon the illumination can be explained by the trap saturation effect. For a TiO₂ nanoparticulate thin film sensitized using CdS nanoparticles, the slow photocurrent response disappears and the steady-state photocurrent increases drastically, which suggests that photosensitization can decrease the effect of surface states on photocurrent response. Electronic Publication     

Preparation of nanocrystalline TiO2 thin film at low temperature and its application in dye-sensitized solar cell

The electrophoretic deposition combined with common pressure hydrothermal treatment was employed to prepare nanocrystalline TiO₂ thin film from suspension of tetra-n-butyl titanate and P25 at low temperature. The tetra-n-butyl titanate was hydrolyzed and crystallized into anatase to interconnect nanocrystalline TiO₂ particles and to stick them to a conductive substrate by common pressure hydrothermal treatment to improve the electron transport properties of the deposited thin film. A dye-sensitized solar cell based on TiO₂ thin film prepared by the low temperature method yielded the conversion efficiency of 6.12%. Due to the relative slower electron transport rate in the deposited film, its conversion efficiency was slightly lower than that of the cell with TiO₂ thin film prepared by the conventional high temperature sintering method. Since it is free of high temperature sintering step, this method can be used to prepare nanocrystalline TiO₂ thin film on plastic polymer conductive substrate for fabrication of flexible dye-sensitized solar cell.     

静电喷雾法制备高效染料敏化太阳能电池的二氧化钛光阳极

TiO2光阳极膜是染料敏化太阳能电池（DSSC）的核心部件之一,它对电池的光电转换效率起决定性作用．TiO2电极一般采用刮涂法和丝网印刷法制备．近3年,通过静电喷雾制备光阳极的方法得到国内外学者的关注．静电喷雾制备光阳极会受到多种因素的影响,如电压、流速、悬浮液浓度、喷雾距离以及喷雾时间等．但这些因素对成膜和DSSC器件性能的影响却没有得到全面的研究或者报道．本文使用静电喷雾法制备了多孔TiO2纳米膜,并研究了以其为电极的电池器件特性．经过超声充分分散的稳定TiO2乙醇悬浮液在高电压下喷雾到导电玻璃上成膜．通过改变电喷雾距离,得到了具有不同形貌的TiO：光阳极膜,并解释了其形成的机理及其对电池性能的影响．研究还表明,光阳极膜的TiC14处理能够很好地改善电池性能．通过优化,基于流速为0．8mL／h、电喷雾距离和时间分别为2．2cm和8min条件下制备的光阳极,结合TiC14处理,组装的电池在模拟太阳光源AM1．5G下光电转化效率达6．24％．     

Dye-sensitized solar cells made from BaTiO3-coated TiO2 nanoporous electrodes

We reported on the preparation of a thin BaTiO₃-coated layer (2.27 nm) on the surface of TiO₂ and its further application in the dye-sensitized solar cells (DSCs). The as-prepared BaTiO₃–TiO₂ films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The performances of the DSCs with and without BaTiO₃ coating were analyzed by cyclic voltammograms (CVs), electrochemical impedance spectroscopy (EIS), and current–voltage measurements. It was found that the BaTiO₃–TiO₂ films with about 12 μm thickness increased the dye adsorption, resulting in increased J_sc. In the meantime, the BaTiO₃ modification on the TiO₂ surface is beneficial to the formation of an energy barrier against the electron transfer from TiO₂ to I₃⁻, providing the increase of V_oc due to the increased electron density in the TiO₂ that is caused by the increased electron lifetime.     

Influence of Modification of Counter Electrode on Photoelectric Properties of Dye-sensitized TiO2 Solar Cells

A dye-sensitized nanocrystalline TiO2 solar cell(DYSC) was assembled, of which counter electrode was modified already by platinum, nickel and carbon. It was found that the DYSC had better photoelectric performance when the electrode was modified by platinum than by nickel and carbon. The influence of the incidence light wavelength on the incidence monochromatic photoelectric conversion effieieney(IPCE) was investigated.The result shows that the IPCE mainly depends on the short-circuit current density(Isc) of a DYSC, and the IPCE reaches 48.32% under the irradiation with the wavelength of 560 nm when the counter electrode of a DYSC was modified by platinum. The influence of incident light intensity on the photoelectric properties of a DYSC was also investigated. It was found that the Isc and open-circuit voltage(Voc) increased and the fill factor(ff) of the DYSC decreased with the increase of the incident light intensity.     

Poly(o-phenylenediamine)/MWNTs composite film as a hole conductor in solid-state dye-sensitized solar cells

All solid-state dye-sensitized solar cells were fabricated using in situ electrochemically polymerized poly(o-phenylenediamine)/MWNTs (PoPD/MWNTs) as a hole transport materiel. The electrochemical behaviors of PoPD/MWNTs indicated that the electron exchange efficiency improves obviously of PoPD after the addition of carbon nanotubes. The PoPD/MWNTs composite film was deposited on the dye anchored porous TiO₂ electrode and I–V characterization was performed under simulated AM 1.5 illumination. Fabricated devices for the PoPD/MWNT composites prepared in 0.1 g/L MWNTs showed a photoresponse with an open-circuit voltage V_OC of 479 mV and a short-circuit current density (I_SC) of 0.572 mA/cm² with the overall conversion efficiency of 0.13%, higher than those of the cell with only PoPD (i.e., I_SC = 0.275 mA/cm², V_OC = 462 mV, FF = 0.35, η = 0.04%). It is obvious that the introduction of MWNTs to PoPD composites could improve the cell performance.     

紫外光照射二氧化钛纳米管沉积纳米金颗粒应用于染料敏化太阳能电池

通过紫外光照射成功把金粒子沉积到二氧化钛纳米管的管壁中。通过扫描电镜、能谱和X射线衍射进行表征。沉积所得的金粒子为高度分散的纳米级粒子,并且金颗粒的粒径和密度可通过沉积时间控制。应用于染料敏化太阳电池中,由于金颗粒存在表面等离子增强效应,可提高电池的光电转换效率。然而随着沉积时间增长,沉积的金颗粒粒径会增大,所得电池的效率将会下降。     

STS study of TiO2 film and Pt-deposited TiO2 film in air

Direct investigation of the electronic structure of catalyst surfaces on the near-atomic scale in general has not been impossible in the past. However, with the advent of the scanning tunneling microscope (STM), the opportunity arises for incorporating the scanning tunneling spectroscopy (STS) for correlation in-situ surface electronic structure with topography on a sub-nanometer scale. In this paper, we report the STS results of thin film TiO2 and Pt-deposited TiO2 annealed at 450℃. It was found that the TiO2 semiconductor changes from n-type to p-type after Pt deposition.Fig. 1 shows the surface electronic property (Ⅰ-Ⅴ curve) of thin TiO2 film measured in air by STS. A steep descent of the anodic tunneling current at ca.- 1.0 Ⅴ and a rapid ascent of cathodic tunneling current at ca. +2.0V. The zero bias represents the Fermi level (Ef). Ef is situated at the Ecb side indicating that the thin TiO2 film possesses the same band gap as that of bulk TiO2 phase ( Egs =3.0 to 3.2 eV). For the sample of Pt-deposited TiO2 film, Pt/(Pt+Ti+O) atomic ratio≈0.2, which indicates that the surface of TiO2 film is partly covered by Pt particles, and there are two types of Ⅰ-Ⅴ curves to be detected. One of them (Fig.2a)is attributed to the electronic property of TiO2, which has same Egs as that shown in Fig. 1. However, the Ef is transferred to valence side (△≈1eV). This phenomenon hints that TiO2 is doped by an impurity which can introduce h+ into TiO2 lattice.Such a type of defects may be described by Ti1-xPtxO2(h )2x, here Pt+2 as a substitutional site of Ti+4. Fig.2b is the Ⅰ-Ⅴ curve of a Pt particle situated on a TiO2 particle contained Ti1-xPtxO2(h )2x.     

Properties of chemical vapour deposited nanocrystalline TiO2 thin films and their use in dye-sensitized solar cells

Nanocrystalline titanium dioxide (TiO₂) thin films have been prepared using titanium(IV) isopropoxide as a precursor onto the glass and fluorine doped tin oxide coated glass substrates by chemical vapour deposition technique at 400 °C substrate temperature. X-ray diffraction study confirms the polycrystalline nature of TiO₂ with anatase phase having tetragonal crystal structure. The films are 975 nm thick and transparent having transmittance grater than 80%. Atomic force microscopy (AFM) images reveal the nanocrystalline morphology with grain size of 200 nm. The film shows a sharp absorption edge near 350 nm. Photoelectrochemical study shows that TiO₂ thin film sensitized with Brown Orange dye is found to exhibit relatively maximum I_sc and V_oc among the studied dyes. The values of fill factor (FF) and efficiency (η) for the dye-sensitized solar cell (Brown Orange dye-sensitized TiO₂) are 0.54 and 0.17%, respectively. Such films would serve as better prospects for dye-sensitized solar cells.     

TiO2/SnO2复合空心球在染料敏化太阳能电池中的应用

采用模板辅助法制备了SnO2/TiO2复合空心球,样品直径为1.5~4.0μm,比表面积达到了92.9 m^2·g^-1,复合空心球表现出优越的光散射性能.以这种复合空心球作为染料敏化太阳能电池的光阳极,电池的光电转换效率可达到7.72%,高于SnO2微米球(2.70%)和TiO2微米球(6.26%).此外,以锐钛矿型TiO2纳米晶作为底层,SnO2/TiO2复合空心球作为光散射层制备的双层结构光阳极,电池光电转换效率进一步提升至8.43%.     

退火气氛对掺银TiO2薄膜结构和光催化性能的影响

本文采用sol-gel法制备了掺银的TiO2/glass纳米光催化薄膜,并分别在空气和真空条件下对薄膜进行退火处理, 结构和光催化性能的测试结果表明, 退火气氛对薄膜的结构和薄膜对染料溶液的光催化降解效率都有影响。经真空退火处理的TiO2及Ag-TiO2薄膜较空气中退火处理的同样薄膜的光催化性能都低, 但适量掺银的Ag-TiO2薄膜的光催化活性较TiO2有不同程度的增强。     

Microwave processing of TiO2 blocking layers for dye-sensitized solar cells

The microwave heat treatment of blocking layers for dye-sensitized solar cells has been investigated. It has been found that the solar cell efficiencies achieved with microwave heating were considerably higher than those achieved with conventional heating at low temperatures (100°C). This was attributed to microwave heating providing better sintering of the blocking layer and better interfacial contact between the substrate and the TiO₂ layers. These results are promising with regard to the application of microwave heating to the production of dye-sensitized solar cells on flexible polymer substrates.     

Controllable preparation of nanosized TiO_2 thin film and relationship between structure of film and its photocatalytic activity

~~Controllable preparation of nanosized TiO_2 thin film and relationship between structure of film and its photocatalytic activity@魏刚$College of Material Science and Engineering,Beijing University of Chemical Technology! Beijing 100029,China @张元晶$College of Material Science and Engineering,Beijing University of Chemical Technology! Beijing 100029,China @熊蓉春$College of Material Science and Engineering,Beijing University of Chemical Technology! Beijing 100029,China~…     

Enhanced Efficiency of Dye-sensitized Solar Cells Using rGO@TiO2 Nanotube Hybrids

We established a novel strategy for the synthesis of reduced graphene oxide(rGO)@TiO₂ nanotube hybrids using an 18 W UV-assisted photo-catalytic reduction method for utilization as photo-anode of dye-sensitized solar cells(DSSCs). The photo-conversion efficiency of DSSCs was significantly enhanced after the addition of rGO, and in addition, the photo-anode showed decreased internal resistance. Analysis of rGO@TiO₂ hybrids by transmissions scanning electron microscopy(TEM), X-ray diffraction(XRD), Raman spectra, N₂ adsorption and desorption, atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS) demonstrates that the rGO modified TiO₂ nanotubes can increase the short-circuit current and the conversion efficiency of dye-sensitized solar cells. The efficiency is improved by almost two folds as much compared to those of the bare TiO₂ nanotubes.     

室温合成金红石TiO2及其在染料敏化太阳能电池中的应用

以钛酸四丁酯为前驱体, 在室温下通过水解沉淀法合成了金红石型TiO₂纳米粒子; 用X射线衍射(XRD)研究了反应温度、酸度以及酸的种类对形成TiO₂晶型的影响. 实验结果表明, 高酸度、低温度以及Cl-有助于金红石相的生成. 在相同条件下加入一定量P105 (EO₃₇PO₅₆EO₃₇)三嵌段聚合物制备出一种金红石型粗糙聚集球. 扫描电子显微镜(SEM)结果表明这种粗糙聚集球直径大约350 nm, 比表面积测试(BET)及紫外漫反射测试发现粗糙球在保持较大比表面积的同时有散射效应. 此粗糙球与20 nm TiO₂粒子以质量比1:4混合作为工作电极的散射层并应用于染料敏化太阳能电池, 电池效率达到7.27%, 较不加粗糙球的效率提高17%; 我们认为这是因为在保持工作电极染料吸附量基本不变的条件下粗糙球提高光散射性能.     

A TiO2@{Mo368} composite: synthesis,characterization, and application in dye-sensitized solar cells

The high-nuclear cluster compound Na₄₈[H_xMo₃₆₈O₁₀₃₂(H₂O)₂₄₀(SO₄)₄₈]·ca.1000H₂O (denoted as {Mo₃₆₈}) represents the known nanoscale hedgehog-type cluster anion with the diameter of approximately 6 nm. Herein, a TiO₂@{Mo₃₆₈} composite was prepared through a sol–gel process for the first time. SEM, XPS, and UV–vis spectra were employed to characterize their chemical composition and structures. Meanwhile, the as-obtained composite was further mixed with P25 (Degussa P25 titania photocatalyst) then applied as the photoanodes of dye-sensitized solar cells (DSSCs); the results showed that DSSCs with the P25-TiO₂@{Mo₃₆₈}-based photoanodes exhibited better performance than that with pure P25-based photoanodes, which was due to less carrier recombination and longer electron lifetime in the former DSSCs by the results from analysis of dark current measurement, electrochemical impedance spectroscopy, and open-circuit voltage decay curve.     

Structural engineering of dipolar organic dyes with an electron-deficient diphenylquinoxaline moiety for efficient dye-sensitized solar cells

A series of new organic dyes containing an electron-deficient diphenylquinoxaline moiety was synthesized and employed as the photosensitizers in dye-sensitized solar cells (DSSCs). The multiple phenyl rings in the peripheral positions of the dye structure provide a hydrophobic barrier to slow down the charge recombination. The photophysical and electrochemical properties of these dyes were investigated in detail. The cell performance and the associated photophysical and electrochemical properties can be easily tuned by the modification of the aromatic fragments within the π spacer. Dye CR204-based DSSC reached the best energy conversion efficiency of 6.49% with an open-circuit voltage of 666 mV, a short-circuit photocurrent density of 14.9 mA cm⁻², and a fill factor of 0.66. The IPCE of CR204-based DSSC covers the light-harvesting to NIR region.