An investigation of DNA-like structured dye-sensitized solar cells

This paper reports a 3D DNA-like structured dye-sensitized solar cell (DSSC) with all-Ti substrates. A self-organized TiO₂ nanotubular arrays layer was directly grown on the photoanode surface by electrochemical anodization. Compared with the traditional flat-type DSSC, the DNA-like DSSC showed superiority of light utilization due to its symmetrical double-helix structure. Different thickness of the nanotubular arrays layers were investigated to find their influence on the cell’s photovoltaic parameters, and the cell with a 15.3 μm layer exhibited the highest P_max, about 0.49 mW. The series–parallel connection characteristics of the DNA-like DSSCs reveal that the total voltage and the total short current equalled the sum of each cell’s in series and in parallel, respectively. It is anticipated that the novel DNA-like structured DSSCs have great application potential in larger modules using integrated circuit.     

Ni3S2@MWCNTs films for effective counter electrodes of dye-sensitized solar cells

Composite films nickel sulfide (Ni₃S₂) nanoparticles were grown on multiwall carbon nanotubes (MWCNTs) and in situ coated onto conducting glass substrates by the hydrothermal process at 170 °C. These Ni₃S₂@MWCNTs films were applied for counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). In this work, nanostructure, crystalline structure, electrochemical activities and electron-charge transfer resistance of CEs were studied. In addition, the effective surface areas of CEs were analyzed and discussed as well. The power conversion efficiency (PCE) enhancement of up to 7.48%, compared with that of Ni₃S₂-DSSC, was demonstrated for a Ni₃S₂@MWCNTs DSSC.     

Controlled synthesis of TiO2-B nanowires and nanoparticles for dye-sensitized solar cells

Controllable synthesis of the TiO₂-B nanowires (NWs) and nanoparticles (NPs) had been achieved via a facile hydrothermal route, respectively, only by tuning the solution volume. The dye-sensitized solar cells prototypes had been fabricated using TiO₂-B NW and NP electrodes, respectively. The TiO₂-B NP cells had higher photocurrent and photoelectrical conversion efficiency than the TiO₂-B NW cells though the latter exhibited larger photovoltage compared to the former. The key factors such as the photogenerated electron injection drive force, surface defects and the interfacial charge transfer, which determined the photoelectrical properties, had been systematically researched with the surface photovoltage spectra (SPS) and the electrochemical impedance spectra (EIS). The SPS proved that there was larger photoelectron injection drive force in TiO₂-B NP photoelectrode than that in NW photoelectrode. And the electrochemical impedance spectra (EIS) revealed that TiO₂-B NP cells had faster interface charge transfer compared to TiO₂-B NW cells. Both proved that NP cells had the higher photocurrents.     

电沉积处理与染料敏化纳米薄膜太阳电池的优化

采用阳极氧化水解法对染料敏化纳米TiO₂薄膜太阳电池的光阳极进行不同方式的电沉积优化处理.借助x射线衍射仪对处理后的样品进行分析，通过超高分辨率场发射扫描电子显微镜对导电玻璃以及电沉积处理前后纳米多孔薄膜表面进行了粒径和形貌的扫描.染料敏化太阳电池实验测试结果表明，电沉积处理和修饰后可以明显提高光生电子的收集率，增大短路电流密度，提高电池效率. 关键词： 2')" href="#">纳米TiO₂ 染料敏化 电沉积 太阳电池     

PEO electrolytes containing dioctyl phthalate (DOP) for dye-sensitized nanocrystalline TiO2 solar cells

In this paper, we aim to prepare polymer electrolytes consisting of NaI and I₂ dissolved in poly(ethylene oxide) (PEO) and dioctyl phthalate (DOP) as an additive and apply the electrolytes to dye-sensitized solar cells (DSSC). Upon the incorporation of salt, the phthalic-stretching C=O bands of DOP in Fourier transform infrared spectra shifted to a lower wave number (Δf = 93 cm⁻¹), confirming the unusual strong complex formation between sodium ions and phthalic oxygen. Coordinative interactions and structural changes of PEO/NaI/I₂/DOP electrolytes have also been characterized by wide angle X-ray scattering, presenting an almost amorphous structure of the polymer electrolytes. The ionic conductivity of the polymer electrolytes reached ∼10^–4 S/cm at room temperature at the mole ratio of [EO]:[Na]:[DOP] = 10:1:0.5, as determined by the four-probe method. DSSC using the polymer electrolytes and conductive indium tin oxide glasses exhibited 2.9% of overall energy conversion efficiency (=P _max/P _in × 100) at one sun condition (100 mW/cm²). The good interfacial contact between the electrolytes and the dye-attached nanocrystalline TiO₂ layers were verified by field-emission scanning electron microscopy.     

XPS characterization of sensitized n-TiO2 thin films for dye-sensitized solar cell applications

TiO₂ thin films, employed in dye-sensitized solar cells, were prepared by the sol-gel method or directly by Degussa P25 oxide and their surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effect of adsorption of the cis-[Ru(dcbH₂)₂(NCS)₂] dye, N3, on the surface of films was investigated. From XPS spectra taken before and after argon-ion sputtering procedure, the surface composition of inner and outer layers of sensitized films was obtained and a preferential etching of Ru peak in relation to the Ti and N ones was identified. The photoelectrochemical parameters were also evaluated and rationalized in terms of the morphological characteristics of the films.     

Formation of single-crystalline TiO2 nanomaterials with controlled phase composition and morphology and the application in dye-sensitized solar cell

Single-crystalline TiO₂ nanomaterials with controlled phase composition and morphology were synthesized by hydrothermal transformation of H-titanate nanotubes under different pH. Rutile rectangle nanorods with two four-side tapered tips were produced at pH of 0, whereas anatase nanoparticles with mainly of rhombic shape were obtained at pH from 2 to 7 and their average particle size increased with pH. The transformation mechanisms at different pH were discussed. The single-crystalline anatase nanoparticles obtained at pH of 2 had ca. 12 nm in average particle size, and the powder possessed as large as 112 m²/g specific surface areas; the conversion efficiency of the dye-sensitized solar cell based on the nanoparticles was increased by over 40% as compared with that of the cell based on P25.     

锐钛矿相TiO2纳米管的制备及其染料敏化太阳电池

以商用金红石相TiO₂粉末为原料,通过在碱性溶液中150℃水热48h的方法合成TiO₂纳米管.采用SEM,TEM,XRD分析手段对TiO₂纳米管的形貌和结构演变进行了表征.制成的TiO₂纳米管与TritonX-100,乙酰丙酮混合后,通过丝网印刷的方法涂敷到ITO导电玻璃衬底上,并且在450℃下烧结30min后得到可应用于染料敏化太阳电池的多孔光阳极.将此光阳极浸泡于N719染料敏化后,与镀铂对电极组装电池,两者之间灌 关键词： 2纳米管')" href="#">TiO₂纳米管 染料敏化太阳电池 水热法     

Cocktail effect of Fe2O3 and TiO2 semiconductors for a high performance dye-sensitized solar cell

The bi-semiconductors of TiO₂ and Fe₂O₃ were used as a photoelectrode material in a high performance dye-sensitized solar cell due to cocktail effects from the two conduction bands. The size of the semiconductors was reduced by using a paint shaker to enlarge the contact area of the semiconductor with the dye or electrolyte. The fill factor and the efficiency of the prepared dye-sensitized solar cell were improved by over 16% and 300%, respectively; these parameters were measured from a current-voltage curve that was based on the effects of the Fe₂O₃ co-semiconductor and the size reduction. A mechanism is suggested wherein the conduction band of Fe₂O₃ works to prohibit the trapping effects of electrons in the conduction band of TiO₂. This result is attributed to the prevention of electron recombination between electrons in the TiO₂ conduction band with dye or electrolytes. The mechanism is suggested based on impedance results, which indicate improved electron transport at the interface of the TiO₂/dye/electrolyte.     

Correlation between microstructure and property of electroless deposited Pt counter electrodes on plastic substrate for dye-sensitized solar cells

Flexible Pt counter electrodes (CEs) were prepared on indium-doped tin oxide coated polyethylene naphthalate (ITO-PEN) substrate by electroless deposition. The correlation between the microstructure and the property of the Pt CEs was investigated. Results showed that isolated Pt nanoparticles were uniformly distributed on the ITO surface at a short deposition duration, and then grew with the deposition duration, leading to the interconnection of adjacent Pt nanoparticles. The interconnection of Pt nanoparticles was beneficial to the electrical property of the Pt CEs, while it was unfavorable to the electrocatalytic property of the Pt CEs. A microstructure model was proposed to explain the correlation between the microstructure and the property of the Pt CEs. In addition, the Pt CEs showed low charge transfer resistance (1.66-0.58 Ω cm²), which was comparable to that (1.16 Ω cm²) of the conventional sputtered Pt CE. The high electrocatalytic property of the electroless deposited Pt CEs makes the assembled DSCs present comparable energy conversion efficiency of the DSCs using sputtered Pt CE.     

Study on the properties and charge generation in dye-sensitized n-TiO2|dye|p-CuI solid state photovoltaic solar cells

Transparent semiconducting copper iodide (CuI) films were prepared by XeCl Excimer laser and their characteristics are investigated. These films exhibited optical transmittance over 80% in the wavelength range from 400 to 900 nm and minimum resistivity of about 2 kΩ cm⁻¹. The optical absorption of the these films shows a remarkable blue shift compared to that of polycrystalline of CuI, which can be explained from the viewpoint formation of ultra fine of CuI grains. The titanium dioxide (TiO₂) films have been prepared by sol-gel method. The properties of pulsed laser deposited CuI and TiO₂ films in power output of n-TiO₂|dye|p-CuI cells is studied. An efficient charge generation is observed through the illumination of TiO₂ layer of the fabricated n-TiO₂|dye|p-CuI solid state photovoltaic solar cells. From the current-voltage characteristics, the fill factor and power conversion efficiency were about of 45 and 3%, respectively. The maximum photo-current of about 12.5 mA/cm² and photo-voltage of 475 mV under AM 1.5 conditions were obtained for the n-TiO₂|dye|p-CuI solid states photovoltaic solar cells with good reproducibility. Adsorbed dye molecules to the TiO₂ surface act as a relay, especially under illumination through TiO₂ layer in the wave range region of 300-400 nm.     

Characterization of nanocrystalline SnO2 thin film fabricated by electrodeposition method for dye-sensitized solar cell application

Nanocrystalline SnO₂ thin film was prepared by cathodic electrodeposition-anodic oxidation and its structure was characterized by X-ray diffraction, SEM, UV-visible absorption and nitrogen adsorption-desorption by BET method. The obtained film has a surface area of 137.9 m²/g with grain sized of 24 nm. Thus the prepared SnO₂ thin film can be applied as an electrode in dye-sensitized solar cell. The SnO₂ electrode was successfully sensitized by Erythrosin dye and photoelectrochemical measurements indicate that the cell present short-circuit photocurrent (J_sc) of 760 μA/cm², fill factor (FF = 0.4), photovoltage (V_oc = 0.21 V) and overall conversion efficiency (η) of 0.06% under direct sun light illumination. The relatively low fill factor and photovoltage are attributed to the reduction of triodiode by conduction band electrons and intrinsic properties of SnO₂.     

Analysis of adsorption properties of N719 dye molecules on nanoporous TiO2 surface for dye-sensitized solar cell

Ordered nanoporous TiO₂ materials (MK-TiO₂, MS-TiO₂, and MU-TiO₂) were synthesized for the dye-sensitized solar cell (DSSC) by using different silica templates such as KIT-6, SBA-15, and MSU-H. To prepare a photoelectrode in DSSC, cis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye (N719) was adsorbed onto the synthesized nanoporous TiO₂ materials. The samples were characterized by XRD, TEM, FE-SEM, AFM, and N₂ adsorption analyses. The photovoltaic performance of DSSC was evaluated from the overall conversion efficiency, fill factor, open-circuit voltage, and short-circuit current from the I-V curves measured. It was found that the photoelectric performance is highly dependent on the adsorption properties of N719 dye molecules on the nanoporous TiO₂ replicas (MK-TiO₂, MS-TiO₂, and MU-TiO₂) synthesized from different silica templates.     

纳米TiO2叶片状阵列电极的制备及其在染料敏化太阳电池中电子的输运性能

在低温条件下采用定向刻蚀技术, 对金属Ti片表面用H₂O₂溶液进行刻蚀氧化, 制备了垂直生长的纳米TiO₂叶片状阵列薄膜电极. 通过X射线衍射分析表明, 纳米TiO₂叶片状阵列薄膜经500 ℃下烧结1 h后, 从无定型转变为锐钛矿相. 场发射扫描电子显微镜观察表明: 在80 ℃下的H₂O₂溶液刻蚀氧化, 经1 d制备得到的是Ti片表面垂直生长的叶片状阵列, 其形貌均匀且完整地 关键词： 2')" href="#">纳米TiO₂ 叶片状阵列电极 染料敏化太阳电池 电子传输     

Investigation of the fill factor of dye-sensitized solar cell based on ZnO nanowire arrays

The fill factor of dye-sensitized solar cells based on the ZnO nanowire array is very low, which is usually ascribed to a rapid charge recombination. In this article, the influence on the fill factor of ZnO nanowire array cell is investigated and discussed by comparing dark current and decay rate of open circuit potential of the ZnO nanowire array cell with those of the ZnO nanoparticle cell, TiO₂ nanoparticle cell and TiO₂-coated ZnO nanowire array cell. The results demonstrate that the low fill factor of the ZnO nanowire array cell is largely caused by a rapid decrease of electron injection efficiency rather than a rapid charge recombination, which is decided by the absorption nature of Ru-complexed dye molecules on ZnO surface and repellency of radial electric field. The fill factor of the ZnO nanowire array cell can be improved by coating ZnO nanowires with a wide band gap semiconductor material or metal oxide insulator.     

TiO2 treatment using ultrasonication for bubble cavitation generation and efficiency assessment of a dye-sensitized solar cell

In this study, the impacts of different ultrasonic treatments on TiO₂ particles were determined and they were used to manufacture the photoelectrodes of a dye-sensitized solar cell (DSSC). Two methods were used to prepare TiO₂ particles directly sonicated by an ultrasonic horn, and TiO₂ treated indirectly by an ultrasonic cleaner. TEM, XPS analysis was confirmed that cavitation bubbles generated during ultrasonication resulted in defects on the surface of TiO₂ particles, and the defect induced surface activation. To understand the effect of TiO₂ surface activation on energy conversion efficiency of DSSC, ultrasonic horn DSSC and ultrasonic cleaner DSSC were prepared. The UV–vis analysis exhibited that the ultrasonic horn DSSC possessed higher dye adsorption when compared to the ultrasonic cleaner DSSC, and the EIS analysis confirmed that the electron mobility was greatly increased in the ultrasonic horn DSSC. The energy conversion efficiency of the ultrasonic horn DSSC was measured to be 3.35%, which is about 45% increase in comparison to that of the non-ultrasonic treated DSSC (2.35%). In addition to this regard, recombination resistance of ultrasonic horn DSSC was calculated to be 450 Ω·cm², increasing more than two times compared to the non-ultrasonic treated DSSC (200 Ω·cm²). Taken together, these ultrasonic treatments significantly improved the energy conversion efficiency of DSSC, which was not tried in DSSC-related research, and might lead us to develop more efficient practical route in the manufacturing of DSSC.     

TiO2 Wedgy Nanotubes Array Flims for Photovoltaic Enhancement

In this study, TiO₂ wedgy nanotubes with rectangular cross-sections were fabricated on transparent conductive substrates by using TiO₂ nanorods as the precursor via the anisotropic etching route. TiO2 nanotubes with V-shaped hollow structure and the special crystal plane exposed on the tube wall possess nature of high surface area for more dye molecules absorption, and the strong light scattering effects and dual-channel for effective electron transport of the TiO₂ V-shaped nanotubes based dye-sensitized solar cell exhibit a remarkable photovoltaic enhancement compared with the TiO₂ nanorods. The photoanode based on our V-shaped TiO₂ nanotubes with a length of 1.5 μm show a 123% increase of the dye loading and a 182% improvement in the overall conversion efficiency when compared with 4 μm rutile TiO₂ nanorods photoanode.     

Application of polyaniline nanowires electrodeposited on the FTO glass substrate as a counter electrode for low-cost dye-sensitized solar cells

Polyaniline nanowires (PANI NWs) were deposited onto fluorine-doped tin oxide (FTO) glass substrate using the cyclic voltammetric method with aniline monomer precursor in HCl aqueous solution. The secondary oxidation peak plays an important role in polymerization of aniline monomer and the optimization of catalytic activity of PANI-based counter electrodes was achieved by controlling the number of cycles. The photovoltaic performance of the dye-sensitized solar cells (DSSCs) with PANI NWs counter electrodes (CEs) was optimized at 4th cycles, and then following parameters were obtained: J_sc = 17.2 mA cm⁻², V_oc = 0.71 V, FF = 59.3%, and efficiency (η) = 7.24%. While, J_sc = 14.7 mA cm⁻², V_oc = 0.77 V, FF = 70.6%, and efficiency (η) = 7.98% in cells with Pt CEs. The PANI NWs were attractive as an alternative CEs for the low-cost DSSCs instead of Pt.