Multi-layered TiO2 nanostructured films for dye-sensitized solar cells

Multi-layered TiO₂ nanostructured films were fabricated to improve the light harvest efficiency of the dye-adsorbed TiO₂ electrode in dye-sensitized solar cells (DSSCs) by light scattering. Three different structures of TiO₂ electrodes, with layers consisting of TiO₂ pastes with average diameters of 9, 20, and 300 nm, respectively, were fabricated and their photovoltaic effects on the DSSC devices were investigated. By utilizing the multi-layered TiO₂ electrode constructed using the three different TiO₂ pastes, the overall power conversion efficiency of the DSSC devices in the PEG-based electrolyte was increased to 5.24% under irradiation of 100 mW/cm² at AM 1.5.     

Enhanced electron lifetime on nitrogen-doped TiO2 films for dye-sensitized solar cells

Nitrogen-doped TiO2 crystallites were prepared via the hydrolysis of TiCl4 using an ammonia medium in an aqueous solution for DSSC photoelectrodes. The optimized photoelectrode for the DSSC was prepared with 9.4 nm sized N-doped TiO2 crystal (BET; 200 m2/g), which provides a relatively high short circuit current and energy conversion efficiency in the DSSC. The photovoltaic performance of the N-doped TiO2 electrode was confirmed using incident photon-to-current efficient spectra, impedance analyses, and Bode-phase plots which proved that the N-doped TiO2 electrode has a significantly enhanced electron lifetime compared with that of the P25 electrode.     

柔性染料敏化太阳能电池TiO2薄膜的低温制备技术

简要介绍了柔性染料敏化太阳能电池的特点,综述了柔性染料敏化太阳能电池中TiO2纳米晶半导体薄膜光电极的低温制备技术.     

Nanostructured TiO2 films for dye-sensitized solar cells prepared by the sol-gel method

TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared materials were characterized by XRD, and an SEM. The observations confirmed the nanocrystalline nature of the TiO2. The reaction parameters, such as the catalyst concentrations, the calcination time, and the calcination temperature were varied during the synthesis in order to achieve nanosize TiO2 particles. The prepared TiO2 particles were coated onto FTO glass using a screen printing technique. The prepared TiO2 films were characterized by UV-vis. The TiO2 particles calcinated at low temperatures showed an anatase phase they grew into a rutile phase when the calcination temperature increased. The size and structure of the TiO2 particles were adjusted to specific surface areas. It was found that the conversion efficiency of the DSSC was highly affected by the properties of the TiO2 particles.     

染料敏化TiO2纳米晶太阳能电池的研究

通过改变TiO2 膜热处理温度来研究染料RuL2 (SCN ) 2 敏化TiO2 纳米晶太阳能电池光电性能。得热处理温度对TiO2 膜的质量有很大的影响。染料RuL2 (SCN) 2 的吸收光谱表明 ,染料RuL2 (SCN) 2 在可见光有很宽且强的吸收 ,是一种很理想的敏化剂。用XRD和UV -Vis等手段分别表征了TiO2 膜和染料。     

Influence of annealing temperature on performance of dye-sensitized TiO2 nanorod solar cells

Single-crystal rutile TiO₂ nanorod (NR) arrays have been synthesized on the fluorine-doped tin oxide substrates, followed by an annealing at 200–600?°C. It is found that DSSCs fabricated using TiO₂ NR arrays which undergo annealing display an increased efficiency than those that do not undergo annealing. The optimal efficiency of 4.42% power conversion is achieved in the DSSC made with 500?°C annealed arrays, which show a 450% increase in the overall conversion efficiency. The improvement is ascribed to the increased light harvesting, the enhanced electric contact and the suppressed recombination of the injected electrons with redox species in the electrolyte.     

TiO2纳米管阵列电极染料敏化太阳能电池

采用电化学阳极氧化法在纯钛片表面制备了高度有序的TiO2纳米管阵列。利用SEM、XRD分别对TiO2纳米管阵列的形貌、晶型进行了表征,并通过线性扫描伏安法对N719染料敏化纳米管阵列电极的光电性能进行了研究。实验结果表明,纳米管阵列的管径和长度随着阳极氧化电压的升高和氧化时间的延长都分别相应增加。同时还发现,通过450℃热处理的TiO2纳米管阵列,具有较好的锐钛矿晶型结构,其光电转化效率为2.1%。     

Nanocrystalline TiO2 films treated with acid and base catalysts for dye-sensitized solar cells

Crystalline size and porosity of TiO₂ films are known to be easily controlled by changing acid or base catalyst concentration. This work investigates the influence of acid/base catalyst treatments of TiO₂ nanoparticles on the efficiency of dye-sensitized solar cells (DSSCs). The results indicate that the performance of DSSC fabricated with base-treated TiO₂ is remarkably better than that fabricated with acid-treated TiO₂ because of different film properties including particle size, shape, film porosity, and surface structure and electron transport phenomena.     

Hierarchical structured TiO2 photoanodes for dye-sensitized solar cells

A novel approach has been developed to fabricate hills-like hierarchical structured TiO2 photoanodes for dye-sensitized solar cells (DSSCs). The appropriately aggregated TiO2 clusters in the photoanode layer could cause stronger light scattering and higher dye loading that increases the efficiency of photovoltaic device. For detailed light-harvesting study, different molecular weights of polyvinyl alcohol (PVA) were used as binders for TiO2 nanoparticles (P-25 Degussa) aggregation. A series of TiO2 films with dissimilar morphology, the reflection of TiO2 films, absorbance of attached dye, amount of dye loading, and performance of fabricated DSSC devices, were measured and investigated. An optimized device had energy conversion efficiency of 4.47% having a higher dye loading and good light harvesting, achieving a 23% increase of short-circuit current J(sc) in DSSCs.     

Holographically defined TiO2 electrodes for dye-sensitized solar cells

We describe a multibeam interference lithography for creating 3D polymeric porous structures. The coating of a TiO(2) shell and subsequent removal of the template produce holographically defined TiO(2) (h-TiO(2)) electrodes. We analyze the morphological features of the h-TiO(2) electrodes and consider their applicability to dye-sensitized solar cells (DSSCs). Specifically, the performance of the h-TiO(2) electrode was evaluated by comparison with a macroporous TiO(2) electrode produced from colloidal crystals. The h-TiO(2) structure possesses a larger specific area than the inverted colloidal crystals because of a bicontinuous air network with the TiO(2) shell. Consequently, the h-TiO(2) electrode can produce a 30% higher photogenerated electron current.     

有序大孔TiO2双层膜的设计合成及其在染料敏化太阳能电池中的应用

以垂直沉积法制备的聚苯乙烯(polystyrene,PS)胶体晶体为模板,钛酸四异丙酯为钛源,通过浸渍-煅烧工艺制备了具有分层次有序结构的大孔TiO2双层膜,并作为光阳极应用于染料敏化太阳能电池(dye-sensitized solar cells,DSSCs)。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、紫外-可见漫反射光谱仪和氮气吸附-脱附分析仪等手段对样品进行了表征。结果表明,有序大孔TiO2薄膜较好地复制了PS模板的三维有序结构,且有较大的比表面积。光电性能测试结果表明,与以纯P25薄膜为光阳极的DSSCs相比,有序大孔TiO2双层膜为光阳极能够明显提高DSSCs的光电转换效率,可从4.16%提高到6.08%。该类型分层次有序结构大孔TiO2双层膜在DSSCs中具有重要的潜在应用价值。     

Organized mesoporous TiO2 films exhibiting greatly enhanced performance in dye-sensitized solar cells

The Pluronic P123 templated mesoporous TiO2 film was grown via layer-by-layer deposition and characterized by a novel methodology based on the adsorption of n-pentane. Multiple-layer depositions did not perturb the mesoporous structure significantly. Our TiO2 film was sensitized by a newly developed Ru-bipyridine dye (N945) and was applied as a photoanode in dye-sensitized solar cell. The 1-microm-thick mesoporous film, made by the superposition of three layers, showed enhanced solar conversion efficiency by about 50% compared to that of traditional films of the same thickness made from randomly oriented anatase nanocrystals.     

Progress in nanostructured photoanodes for dye-sensitized solar cells

Solar cells represent a principal energy technology to convert light into electricity. Commercial solar cells are at present predominately produced by single- or multi-crystalline silicon wafers. The main drawback to silicon-based solar cells, however, is high material and manufacturing costs. Dye-sensitized solar cells (DSSCs) have attracted much attention during recent years because of the low production cost and other advantages. The photoanode (working electrode) plays a key role in determining the performance of DSSCs. In particular, nanostructured photoanodes with a large surface area, high electron transfer efficiency, and low electron recombination facilitate to prepare DSSCs with high energy conversion efficiency. In this review article, we summarize recent progress in the development of novel photoanodes for DSSCs. Effect of semiconductor material (e.g. TiO₂, ZnO, SnO₂, N₂O₅, and nano carbon), preparation, morphology and structure (e.g. nanoparticles, nanorods, nanofibers, nanotubes, fiber/particle composites, and hierarchical structure) on photovoltaic performance of DSSCs is described. The possibility of replacing silicon-based solar cells with DSSCs is discussed.     

TiO2-grafted multi-walled carbon nanotubes for dye-sensitized solar cells

Dye-Sensitized Solar Cells (DSSCs) comprised of TiO2 porous films with multi-walled carbon nanotubes (MWNT) were prepared at low temperature (150 degrees C). MWNT were incorporated to facilitate the fast electron transport resulting from metallic properties of carbon nanotubes. In order to enhance the effect of MWNT incorporation, TiO2-grafted MWNT (TiO2-MWNT) was synthesized which can increase the electron transport rate further due to proximity of TiO2 to MWNT The presence of TiO2 nanoparticles on the surface of MWNT was confirmed by electron microscopy and energy dispersive X-ray spectroscopy. As in the DSSCs prepared through high temperature sintering of photoanodes, the maximum content of MWNT incorporated into TiO2 was limited to 0.01 wt% relative to TiO2. TiO2 photoanodes including TiO2-grafted MWNT (TiO2-MWNT/P25) enhanced the cell efficiencies by ca. 28% and 14%, relative to TiO2 photoanodes without and with MWNT respectively, reaching the efficiency of 5.0%. Electrochemical impedance spectroscopy (EIS) was utilized to examine the effect of incorporation of TiO2 nanoparticles grafted to MWNT on the cell performance.     

Enhanced electron transport in mesoporous TiO2 films modified by sol-gel necking for dye-sensitized solar cells

Mesoporous TiO2 films modified via sol-gel necking were fabricated by dispersing Ti tetra-isopropoxide (TTIP; 8 to 16 wt% over TiO2) with TiO2 nanoparticles in isopropyl alcohol. The dye-sensitized solar cells (DSSCs) with 13 wt% TTIP-modified TiO2 film exhibited significantly improved overall energy conversion efficiency, despite having less adsorbed dye when compared with DSSCs with untreated and TiCl4 post-treated TiO2 films. The improvement can be attributed to the sol-gel necking (or interconnection) between the nanoparticles which leads to a much faster electron transport and a suppression of the recombination (or back electron transfer) between the TiO2 and electrolyte.     

染料敏化太阳能电池的TiO2光电极的制备及优化

讨论了染料敏化太阳能电池的TiO2光电极制备与优化工艺过程,这主要包括TiO2薄膜厚度的优化,利用TiCl4处理导电玻璃以及添加大粒子散射层.研究结果表明,当TiO2光阳极厚度为11μm时,电池的转换效率最高.添加TiO2大粒子散射层后,增强了光阳极对光的吸收,当大粒子散射层为4.4μm时,电池的光电性能最好.对TiO...     

介孔TiO2微球水热法合成及在染料敏化太阳能电池中的应用

以Ti(SO4)2为钛源,采用尿素辅助水热法合成了介孔TiO2微球,利用XRD、FESEM和比表面积分析仪对样品的晶型、形貌和比表面积进行分析,探讨了尿素加入量对TiO2微球的颗粒尺寸、比表面积、孔径和孔容的影响。采用刮涂法,用所合成的介孔TiO2微球制备了染料敏化太阳能电池(DSSC)的光阳极,结果表明,尿素用量为1.2g合成的介孔TiO2微球所组装的电池在模拟太阳光的照射下(100mW/cm2,AM1.5),光电转换效率为6.2%,明显高于商用P25纳晶所组装的电池光电转换效率(4.24%)。     

Enhanced photocurrent of nitrogen-doped TiO2 film for dye-sensitized solar cells

Nitrogen (n)-doped titanium dioxide (TiO₂) was prepared with varying doping extent by a general sol–gel process with a pure TiO₂ film as the control sample. The n-doped-2 electrode showed the maximum conversion efficiency with an open-circuit voltage (V_oc) of 0.726 V, a photocurrent (J_sc) of 10.52 mA cm^?2, a fill factor of 63.6%, and an efficiency of 4.86%, compared to 0.751 V, 7.4 mA cm^?2, 67.1%, and 3.73%, respectively, for the undoped (u-doped) TiO₂ electrode. The approximate 23% enhancement in the conversion efficiency of the n-doped-2 TiO₂ electrode-based dye-sensitized solar cells (DSSCs) was mostly ascribed to the increase of light absorption in the near-vis absorbance and partially to the morphological characteristics of the n-doped TiO₂ film. Additionally, the doping type of nitrogen in the TiO₂ lattice was closely studied using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The relation between the doping type and the electron behavior in the DSSCs was also examined.     

Effect of the substrate temperature on the properties of spray-deposited SnO2:F thin films

The effect of the substrate temperature on the properties of spray-deposited SnO₂:F thin films is investigated. X-ray diffraction patterns show that the crystallinity of the films is enhanced with the increasing of substrate temperature. Comparing the SEM images, both the particle size and density are increased at a higher deposition temperature. The lowest sheet resistance of 8.43 Ω/□ is obtained at the substrate temperature of 350 °C. In addition, the average optical transmittance of the three films reaches up to 85 % in the visible range. The absorption coefficient is the lowest at 350 °C. The band gap increases from 3.36 to 3.61 eV while the electrical resistivity of SnO₂:F thin films decreases from 8.51 × 10^?3 to 9.86 × 10^?4 Ω cm as elevating the substrate temperature from 250 to 350 °C.