Dye-sensitized solar cells based on a single-crystalline TiO2 nanorod film

Highly crystalline TiO2 nanorods with lengths of 100-300 nm and diameters of 20-30 nm have been synthesized by a hydrothermal process in a cetyltrimethylammonium bromide surfactant solution. The microstructure measured by X-ray diffraction and high-resolution transmission electron microscopy was a pure highly crystalline anatase phase with a long nanorod shape. The addition of a triblock copolymer poly(ethylene oxide)100-poly(propylene oxide) 65-poly(ethylene oxide)100 (F127) decreased the length of the nanorods and kept the rod shape of the particles even after sintering at high temperatures. The rod shape kept under high calcination temperatures contributed to the achievement of the high conversion efficiency of light-to-electricity as discussed in the paper. A high conversion efficiency of light-to-electricity of 7.29% was obtained with the TiO2 single-crystalline anatase nanorod cell.     

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%.     

Performance of dye-sensitized solar cells based on various sensitizers applied on TiO2-Nb2O5 core/shell photoanode structure

The present investigation described the performance of dye-sensitized solar cells (DSSCs) based on various sensitizers applied on TiO₂-Nb₂O₅ core/shell photoanode film. The novel photoanodes were prepared using composite of TiO₂ nanoparticles (TNPs) and TiO₂ nanorods (TNRs) as core (TNPRs) layer with Nb₂O₅ shell coating. As well, tantalum pentoxide (Ta₂O₅), a blocking layer applied over the core/shell film. The DSSCs were fabricated based on various sensitizers namely zinc phthalocyanine, indoline, indigo carmine, zinc porphyrin, N719, coumarin NKX-2700, polymer dye, quantum dots (QDs), perylene and squaraine. The I–V characteristics of the DSSCs, photocurrent density (Jsc), open-circuit voltage (Voc), fill factor (FF), and photoconversion efficiency (PCE) were determined under illumination of AM 1.5 G. Electrochemical impedance spectroscopy (EIS) analysis is carried out to study the charge transport and life-time of charge carriers at photoanode/dye/electrolyte interface of the DSSCs. The I–V and EIS results explicated that the core/shell with blocking layers were able to alleviate the electron transport and suppressed charge recombination at photoanode/dye/electrolyte interface of the DSSCs. Concerning the sensitizers, PCE of the DSSCs exemplify the order N719 > zinc porphyrin > coumarin NKX-2700 > indoline > squaraine > QDs > zinc phthalocyanine > perylene > polymer dye > indigo carmine dye. The results of the present work demonstrated that among the sensitizers studied, N719 showed the highest PCE and fill factor. Besides, the metal-free organic sensitizers (coumarin NKX-2700 and indoline) exhibited comparable PCE as compared to N719.     

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％．     

Improved photoelectric performance of DSSCs based on TiO2 nanorod array/Ni-doped TiO2 compact layer composites film

Journal of Solid State Electrochemistry - In spite of the TiO2 compact layer (TCL) being widely used, it still needs more study. This paper took Ni-doped TCLs as the research target, using an...     

Kinetics of electron recombination of dye-sensitized solar cells based on TiO2 nanorod arrays sensitized with different dyes

The performance and electron recombination kinetics of dye-sensitized solar cells based on TiO(2) films consisting of one-dimensional nanorod arrays (NR-DSSCs) which are sensitized with dyes N719, C218 and D205, respectively, have been studied. It has been found that the best efficiency is obtained with the dye C218 based NR-DSSCs, benefiting from a 40% higher short-circuit photocurrent density. However, the open circuit photovoltage of the N719 based cell is 40 mV higher than that of the organic dye C218 and D205 based devices. Investigation of the electron recombination kinetics of the NR-DSSCs has revealed that the effective electron lifetime, τ(n), of the different dye based NR-DSSCs shows the sequence of C218 > D205 > N719. The higher V(oc) with the N719 based NR-DSSC is originated from the more negative energy level of the conduction band of the TiO(2) film. In addition, in comparison to the DSSCs with the conventional nanocrystalline particles based TiO(2) films, the NR-DSSCs have shown over two orders of magnitude higher τ(n) when employing N719 as the sensitizer. Nevertheless, the τ(n) of the DSSCs with the C218 based nanorod arrays is only ten-fold higher than that of the nanoparticles based devices. The remarkable characteristic of the dye C218 in suppressing the electron recombination of DSSCs is discussed.     

Dual-functional ZnO nanorod aggregates as scattering layer in the photoanode for dye-sensitized solar cells

A bilayered ZnO photoanode was constructed for dye-sensitized solar cells with a high conversion efficiency of 4.0%. One layer made of ZnO nanocrystallites increases dye adsorption, and the other consisting of ZnO nanorod aggregates provides a directed electron pathway for the electron transport together with a prominent aggregation-induced light scattering.     

Efficient dye-sensitized solar cells based on surfactant-mediated TiO2 nanostructures

Journal of Solid State Electrochemistry - Dye-sensitized solar cells (DSSCs) based on TiO2 nanostructures have attracted much attention due to their high photoconversion efficiency. Here, we report...     

Rectangular bunched rutile TiO2 nanorod arrays grown on carbon fiber for dye-sensitized solar cells

Because of their special application in photovoltaics, the growth of one-dimensional single-crystalline TiO(2) nanostructures on a flexible substrate is receiving intensive attention. Here we present a study of rectangular bunched TiO(2) nanorod (NR) arrays grown on carbon fibers (CFs) from titanium by a "dissolve and grow" method. After a corrosion process in a strong acid solution, every single nanorod is etched into a number of small nanowires. Tube-shaped dye-sensitized solar cells are fabricated by using etched TiO(2) NRs-coated CFs as the photoanode. An absolute energy conversion efficiency of 1.28% has been demonstrated under 100 mW cm(-2) AM 1.5 illumination. This work demonstrates an innovative method for growing bunched TiO(2) NRs on flexible substrates that can be applied in flexible devices for energy harvesting and storage.     

A novel catalyst of WO2 nanorod for the counter electrode of dye-sensitized solar cells

Tungsten dioxide (WO(2)) nanorods were synthesized, which showed excellent catalytic activity for the reduction of triiodide to iodide. The dye-sensitized solar cell (DSC) using WO(2) as a counter electrode (CE) reached a high energy conversion efficiency of 7.25%, which can match the performance of the DSC based on a Pt CE.     

A topotactic tailored synthesis of waxberry-like mixed-phase TiO2 hollow spheres for dye-sensitized solar cells

The waxberry-like mixed-phase Ti O₂hollow microstructures （WMTHMs） are controllably prepared via a topotactic synthetic method,involving the synthesis of monodispersed Ca Ti O₃precursors by a solvothermal method and subsequently transforming them into Ti O₂through a Na₂EDTA-assisted ion-exchange process.The ratio of anatase-rutile is adjustable,and the two phases are connected well with each other.WMTHMs are composed of radially aligned nanorods,speedi...     

Dynamics of charge transport and recombination in ZnO nanorod array dye-sensitized solar cells

Intensity modulated photovoltage and photocurrent spectroscopies reveal that photoanodes based on nanorod arrays exhibit dramatically faster electron transport while retaining similar electron lifetimes (recombination times) compared to standard photoanodes assembled from colloidal nanoparticles.     

Sponge-like TiO2 layers for dye-sensitized solar cells

A titanium oxide layer used in a dye-sensitized solar cell (DSSC) has to meet two opponent properties to enable high conversion efficiency: a large surface area (for high dye loading) and good connection between TiO₂ grains (for efficient extraction of electrons toward the front contact). In order to meet a trade-off between these criteria a preparation method for TiO₂ paste formulation based on Pechini sol–gel method and commercial nanocrystalline TiO₂ powder has been developed. A series of TiO₂ pastes with different molar ratios between titanium isopropoxide, citric acid and ethylene glycol (1:X:4X) in the paste have been examined. The structure and morphology as well as cross-cut tests of deposited and sintered TiO₂ layers have been analyzed. Results reveal that the paste with X = 8 exhibits the best properties, resulting in an overall conversion efficiency of DSSC under standard test conditions (100 mW/cm², 25 °C, AM 1.5G) up to 6.6% for ionic liquid based electrolyte.     

Anisotropic TiO2 nanomaterials in dye-sensitized solar cells

The review presented below summarizes the up-to-date research efforts in using one-dimensional TiO(2) nanomaterials in dye-sensitized solar cells. A brief account of the methods of synthesis of the anisotropic nanomaterials as well as their photovoltaic performance in DSCs was summarily presented. The usefulness of the materials as scattering layer in DSCs was also surveyed.     

Flexible fiber-type dye-sensitized solar cells based on highly ordered TiO2 nanotube arrays

A double-sided, transparent conducting and flexible dye-sensitized solar cell (DSSC) was developed. The device comprised two metal electrodes whereby the working electrode consisted of highly ordered titania (TiO₂) nanotube arrays. The maximum conversion efficiency of the DSSC was 5.1% and decreased by 6% under a 90° bending. Surface treatment of the TiO₂ nanotube arrays in niobium isopropoxide solution lifted the conversion efficiency to 6.8%.     

Double-layer coating of SrCO3/TiO2 on nanoporous TiO2 for efficient dye-sensitized solar cells

Surface modification plays a crucial role in improving the efficiency of dye-sensitized solar cells (DSSCs), but the reported surface treatments are in general superior to the untreated TiO(2) but inferior to the typical TiCl(4)-treated TiO(2) in terms of solar cell performance. This work demonstrates a two-step treatment of the nanoporous titania surface with strontium acetate [Sr(OAc)(2)] and TiCl(4) in order, each step followed by sintering. An electronically insulating layer of SrCO(3) is formed on the TiO(2) surface via the Sr(OAc)(2) treatment and then a fresh TiO(2) layer is deposited on top of the SrCO(3) layer via the TiCl(4) treatment, corresponding to a double layer of Sr(OAc)(2)/TiO(2) coated on the TiO(2) surface. As compared to the typical TiCl(4)-treated DSSC, the Sr(OAc)(2)-TiCl(4) treated DSSC improves short-circuit photocurrent (J(sc)) by 17%, open-circuit photovoltage (V(oc)) by 2%, and power conversion efficiency by 20%. These results indicate that the Sr(OAc)(2)-TiCl(4) treatment is better than the often used TiCl(4) treatment for fabrication of efficient DSSCs. Charge density at open circuit and controlled intensity modulated photocurrent/photovoltage spectroscopy reveal that the two electrodes show almost same conduction band level but different electron diffusion coefficient and charge recombination rate constant. Owing to the blocking effect of the SrCO(3) layer on electron recombination with I(3)(-) ions, the charge recombination rate constant of the Sr(OAc)(2)-TiCl(4) treated DSSC is half that of the TiCl(4)-treated DSSC, accounting well for the difference of their V(oc). The improved J(sc) is also attributed to the middle SrCO(3) layer, which increases dye adsorption and may improve charge separation efficiency due to the blocking effect of SrCO(3) on charge recombination.     

A novel architecture of poly(tetrafluoroethylene)-framed TiO2 electrodes for dye-sensitized solar cells

A novel architecture of polytetrafluoroethylene (PTFE)-framed TiO₂ electrodes is developed for dye-sensitized solar cells. The PTFE-framed TiO₂ electrodes with various thicknesses have been successfully fabricated, ranging from 20 to 160 μm. The optimal energy conversion efficiency of 9.04% is achieved with a film thickness of 60 μm. The PTFE-framed structure not only provides tunable film thickness but a reliable and cost-effective way for the mass production of photo-electrodes.     

Preparation of large-area dye-sensitized solar cells based on hydrothermally synthesized nitrogen-doped TiO2 powders

Low-cost, yellowish, nanocrystalline nitrogen-doped titanium dioxide (N-doped TiO₂) powder was synthesized by a hydrothermal method. The as-prepared N-doped TiO₂ powder was characterized by X-ray diffraction, transmission electron microscopy (TEM), UV–Vis absorption spectra, X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller analysis techniques. The grain size of the prepared powder was around 13 nm as estimated by both Scherrer’s method and TEM images. The effect of the ratio of N-doped TiO₂ particles to Degussa P25 on the photovoltaic performance of large-area dye-sensitized solar cells (DSSCs) was also investigated. The N-doped TiO₂ electrode showed higher photovoltaic performance compared with that of pure P25 at constant irradiation of 100 mW cm^?2, which is attributed to the large pore size and high surface area of N-doped TiO₂ resulting in the introduction of extra charge carrier pathways that could be beneficial for overall charge transportation. Energy conversion efficiency of 5.12 % was achieved in a DSSC device with active area of 51.19 cm².     

两步电泳沉积制备TiO2光阳极用于高效染料敏化太阳能电池

采用不同沉积电压制备TiO₂光阳极,研究电压对薄膜沉积速率、厚度和形貌的影响。通过台阶仪、光学照片、扫描电子显微镜(SEM)、电化学交流阻抗谱、开路电压衰减曲线对光阳极和电池进行系统表征,并测试了染料敏化太阳能电池器件的电流密度-电压(J-V)曲线,计算其光电转换效率。结果表明,提高沉积电压时,光阳极薄膜的沉积速率加快,膜厚也增加,但是电压过高时,薄膜会有裂缝和覆盖不全的问题,这会对电池的效率造成负面影响。综合考虑低沉积电压条件下薄膜均匀无裂缝和高沉积电压条件下沉积速率快的优点,采用先30 V电压、后60 V电压的电泳沉积方式来制备光阳极,结果呈现协同效果,既降低了制备时间又得到高质量的薄膜,在无其他修饰的情况下,电池的光电转换效率可以达到7.29%。     

两步电泳沉积制备TiO2光阳极用于高效染料敏化太阳能电池

采用不同沉积电压制备TiO₂光阳极,研究电压对薄膜沉积速率、厚度和形貌的影响。通过台阶仪、光学照片、扫描电子显微镜（SEM）、电化学交流阻抗谱、开路电压衰减曲线对光阳极和电池进行系统表征,并测试了染料敏化太阳能电池器件的电流密度-电压（J-V）曲线,计算其光电转换效率。结果表明,提高沉积电压时,光阳极薄膜的沉积速率加快,膜厚也增加,但是电压过高时,薄膜会有裂缝和覆盖不全的问题,这会对电池的效率造成负面影响。综合考虑低沉积电压条件下薄膜均匀无裂缝和高沉积电压条件下沉积速率快的优点,采用先30 V电压、后60 V电压的电泳沉积方式来制备光阳极,结果呈现协同效果,既降低了制备时间又得到高质量的薄膜,在无其他修饰的情况下,电池的光电转换效率可以达到7.29%。