染料敏化太阳能电池非铂对电极研究进展

对电极作为染料敏化太阳能电池（dye-sensitized solar cell,DSSC）的重要组成部分,对电极材料性能的好坏直接影响着染料敏化太阳能电池的光电转化效率。最常使用的对电极电催化材料是贵金属铂,而铂十分稀少而且价格昂贵,并且铂很容易被碘电解液腐蚀,不利于染料敏化太阳能电池的产业化发展。本文重点综述了2010年以来染料敏化太阳能电池非铂对电极的研究成果,简要说明了对电极在染料敏化太阳能电池中的作用,详细介绍了非铂金属、碳材料、导电聚合物和无机化合物等对电极材料,分析了各类非铂对电极材料的特点、制备工艺、发展前景、优缺点和改进措施。最后提出,继续开发各种成本低、原料易得以及稳定高效的新型非金属对电极材料仍是今后染料敏化太阳能电池研究的一个重要方向。     

The effect of foamed cement nanocomposite as counter electrode on the performance of dye-sensitized solar cell

Improper interparticle connection between carbon-based materials, poor interface bonding between the carbon counter electrodes (CEs) and substrate, and low surface area are the main limitations of carbon-based CEs in dye-sensitized solar cells. In this study, we utilized foamed cement and binder for adherence and surface area improvement in carbon-based CEs, such as graphite, multi-walled carbon nanotubes, and carbon black (CB). The results revealed that incorporating foamed cement into carbon materials improved the resistance, short-circuit current density, fill factor, and power conversion efficiency of the device. The porous cement/CB nanocomposite CE with a photoconversion efficiency of 5.51% exhibited the best photovoltaic performance. Moreover, this nanocomposite electrode showed an enhancement catalytic activity by high current density in cyclic voltammogram, low charge transfer resistance $(R_{CT}$) in electrochemical impedance spectroscopy, and high exchange current density in Tafel measurements compared to other electrodes. The porosity of foamed cement has been found to be the main cause of its superior photovoltaic performance, which expands the contact area with the electrode and enables rich ion transport. Additionally, the enhanced performance was due to strong bonding, crack-free deposited films, superior conductivity, and high catalytic activity.     

Nanostructured polyaniline counter electrode for dye-sensitised solar cells: Fabrication and investigation of its electrochemical formation mechanism

Nanostructured polyaniline films with controlled thickness have been successfully grown on fluorine-doped tin oxide (FTO) glass substrates using the cyclic voltammetry (CV) method at room temperature. The formation mechanism of the polyaniline film is monitored by CV techniques, alternating current (AC) impedance spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). It is found that the accumulation of nanostructured polyaniline (>70 nm) on both the scattered and compact layers simultaneously increased the reactive interface, which supports charge transfer at the interface and resistance that hinders electronic transport in the film. By optimising the preparation conditions, the short-circuit photocurrent density of a dye-sensitised solar cell (DSSC) with a PANI counter electrode (CE) increased by 11.6% in comparison to a DSSC with an electrodeposited platinum CE.     

Improvement of performance of dye-sensitized solar cells based on electrodeposited-platinum counter electrode

Platinum nanoparticle was electrodeposited on FTO conducting glass substrate as counter electrode for application in dye-sensitized solar cells (DSSCs). Images of transmission electron microscope (TEM) and Scanning Electron Microscope (SEM) showed that platinum nanoparticle was with the mean size of 20-30 nm and was homogeneously distributed on the surface of the FTO conductive glass sheet. Using such a counter electrode, DSSC showed a 6.40% overall energy conversion efficiency under one sun illumination. It exhibited the same high-performance as the DSSC with a platinum counter electrode prepared by electroplating. Furthermore, the present preparation method for the platinum counter electrode has the advantage of low platinum loading and transparence.     

A study of TiO2/carbon black composition as counter electrode materials for dye-sensitized solar cells

This study describes a systematic approach of TiO₂/carbon black nanoparticles with respect to the loading amount in order to optimize the catalytic ability of triiodide reduction for dye-sensitized solar cells. In particular, the cell using an optimized TiO₂ and carbon black electrode presents an energy conversion efficiency of 7.4% with a 5:1 ratio of a 40-nm TiO₂ to carbon black. Based on the electrochemical analysis, the charge-transfer resistance of the carbon counter electrode changed based on the carbon black powder content. Electrochemical impedance spectroscopy and cyclic voltammetry study show lower resistance compared to the Pt counter electrode. The obtained nanostructures and photo electrochemical study were characterized.     

天然染料在染料敏化太阳能电池中的研究进展

染料敏化太阳能电池(DSSCs)为无机固态光伏电池提供了可靠的可代替概念。染料敏化太阳能电池的光电转换效率主要依赖于纳米晶多孔半导体TiO2薄膜电极的染料。由于天然染料的低成本和工艺制备简单的优点,天然染料作为敏化剂已成为DSSC研究热点。作为DSSC的敏化剂的天然染料,如花青素类、胡萝卜素类、叶绿素类、类黄酮,可从不同植物不同部分提取出。主要介绍和讨论天然敏化剂的发展和实用化必须解决的关键问题。     

Carbon nanotube counter electrode for high-efficient fibrous dye-sensitized solar cells

ABSTRACT: High-efficient fibrous dye-sensitized solar cell with carbon nanotube (CNT) thin films as counter electrodes has been reported. The CNT films were fabricated by coating CNT paste or spraying CNT suspension solution on Ti wires. A fluorine tin oxide-coated CNT underlayer was used to improve the adherence of the CNT layer on Ti substrate for sprayed samples. The charge transfer catalytic behavior of fibrous CNT/Ti counter electrodes to the iodide/triiodide redox pair was carefully studied by electrochemical impedance and current-voltage measurement. The catalytic activity can be enhanced by increasing the amount of CNT loading on substrate. Both the efficiencies of fibrous dye-sensitized solar cells using paste coated and sprayed CNT films as counter electrodes are comparative to that using Pt wires, indicating the feasibility of CNT/Ti wires as fibrous counter electrode for superseding Pt wires.     

Low temperature preparation of a high performance Pt/SWCNT counter electrode for flexible dye-sensitized solar cells

A platinum/single-wall carbon nanotube (Pt/SWCNT) film was sprayed onto a flexible indium-doped tin oxide coated polyethylene naphthalate (ITO/PEN) substrate to form a counter electrode for use in a flexible dye-sensitized solar cell using a vacuum thermal decomposition method at low temperature (120 °C). The obtained Pt/SWCNT electrode showed good chemical stability and light transmittance and had lower charge transfer resistance and higher electrocatalytic activity for the I₃⁻/I⁻ redox reaction compared to the flexible Pt electrode or a commercial Pt/Ti electrode. The light-to-electric energy conversion efficiency of the flexible DSSC based on the Pt/SWCNT/ITO/PEN counter electrode and the TiO₂/Ti photoanode reached 5.96% under irradiation with a simulated solar light intensity of 100 mW cm⁻². The efficiency was increased by 25.74% compared to the flexible DSSC with an unmodified Pt counter electrode.     

Nanocomposites of Bi5FeTi3O15 with MoS2 as novel Pt-free counter electrode in dye-sensitized solar cells

Bi₅FeTi₃O₁₅ (BFTO) nanofibers with diameters in the range of 40–100 nm have been fabricated by sol-gel based electrospinning technique. The structure and morphology of the nanofibers were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The MoS₂ nanoparticles are uniformly dispersed into the BFTO, forming nanocomposites. The optical bandgap of the nanocomposites decreases as MoS₂ content increases. The nanocomposites with different MoS₂ contents serve as low-cost counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Through photocurrent–voltage curves, electrochemical impedance spectroscopy and Tafel curves, the performance of the CEs indicates that the charge transfer resistance on the electrolyte-electrode interface lower and the catalytic activity for reduction of triiodide to iodide enhance with the increase of MoS₂ concentration. The DSSC with the CE exhibits a power conversion efficiency of 5.20% after the optimization of the content of MoS₂, which is almost 24 times larger than that of the pure BFTO CE.     

Stability study of carbon-based counter electrodes in dye-sensitized solar cells

This study describes a systematic investigation of the stability of a carbon/TiO₂ counter electrode for use in dye-sensitized solar cells (DSSCs). In this system, nanoparticle additives were introduced by adding Ti-hydrogel. The additives then bound carbon particles and enhanced the adhesion of carbon materials to the conductive substrate. After introducing the Ti-hydrogel into the carbon paste, the carbon/Ti-hydrogel composited counter electrode (HC-CE) showed a better conductivity and stability compared with that of the carbon counter electrode (C-CE), while the catalytic activity was not influenced. The device based on the HC-CE showed superior power conversion efficiency (6.3%) and long-term stability over the device based on the C-CE (5.8%).     

Investigation of low cost carbonaceous materials for application as counter electrode in dye-sensitized solar cells

The structural and morphologic properties of different carbonaceous materials were studied by X-ray diffraction (XRD), Brunauer–Emmet–Teller (BET) porosimetry and transmission electron microscopy (TEM) analyses. The electrochemical behaviour of these powders used as counter electrode in dye-sensitized solar cells (DSSCs) was investigated by polarization experiments and electron impedance spectroscopy. Results were compared with DSSC using Pt as counter electrode. All DSSCs based on the carbonaceous materials showed conversion efficiencies higher than those equipped with Pt. Among the various carbon materials investigated, Acetylene Black in conjunction with graphite showed the best performance. This was interpreted from the physico-chemical analysis as due to a compromise between pores accessibility for the I₃ ^? reactant presents in electrolyte and appropriate surface graphiticity index of this carbonaceous material. A high degree of graphitization for the carbon black was found to enhance electron conduction and charge transfer properties.     

Controlled synthesis of various ZnO nanostructured materials by capping agents-assisted hydrothermal method for dye-sensitized solar cells

In this work, the morphology of ZnO materials could be controlled by changing the capping agent at constant alkali solution in hydrothermal process. ZnO nanomaterials with the structure of flowers, sheet-spheres and plates were obtained with the capping agent of ammonia, citric acid and oxalic acid, respectively. Thus prepared ZnO nanomaterials were characterized and applied as the photo-anode materials for dye-sensitized solar cell. All synthesized ZnO nanomaterials possessed high crystalline wurtzite structures grown in the (0 0 1) direction with the size of 2-4 μm, which consist of ZnO units around 20-400 nm. Among them, Sheet-sphere ZnO showed the highest crystallinity, surface area and uniform film morphology, resulting in the significantly improved PV performance with the overall conversion efficiency of 2.61% in dye-sensitized solar cell (DSSC) fabricated with sheet-sphere ZnO. It is notable that the ZnO materials with sphere structure may be the optimal photo-anode material among various ZnO nanomaterials for DSSC.     

Highly efficient bio-based porous carbon hybridized with tungsten carbide as counter electrode for dye-sensitized solar cell

Bio-based porous carbon (C_MA and C_TA) are successfully prepared from waste carton via microwave-assisted activation (MA) and two-step chemical activation (TA) methods, respectively. The as-prepared C_TA sample exhibits higher specific surface area (824.16 m² g⁻¹) and larger total pore volume (0.71 cm³ g⁻¹), as compared with those of the C_MA sample (655.36 m² g⁻¹ and 0.62 cm³ g⁻¹, correspondingly). The higher specific surface area could provide more catalytic sites; thus, the dye-sensitized solar cell (DSSC) assembled with a C_TA counter electrode (CE) deliver a power conversion efficiency (PCE) of 6.76%, surpass the C_MA-based DSSC (6.19%). Further, tungsten carbide (WC) are introduced into C_TA and C_MA to form hybrid catalysts (WC/C_TA and WC/C_MA, respectively) in order to improve their catalytic activities. Benefitting from the synergistic effect of bio-based porous carbon and WC, the DSSCs with WC/C_TA and WC/C_MA CEs exhibit superior PCE values of 7.32% and 6.85%, respectively, close to Pt (7.51%). This work provides an effective strategy for synthesizing low-cost and high-performance hybrid catalysts from bio-based carbon to achieve resource utilization of biomass waste in new energy fields.     

Fabrication and characterization of carbon-based counter electrodes prepared by electrophoretic deposition for dye-sensitized solar cells

Three different carbon-based counter electrodes are investigated in light of catalytic activities such as electrochemical frequencies and interface impedances. We fabricated carbon-based counter electrodes of dye-sensitized solar cells [DSSCs] using graphene, single-walled carbon nanotubes [SWNTs], and graphene-SWNT composites by electrophoretic deposition method. We observed the optical and electrochemical properties of the carbon-based counter electrodes. The DSSC with the graphene-deposited counter electrode demonstrated the best conversion efficiency of 5.87% under AM 1.5 and 1 sun condition. It could be utilized for a low-cost and high-throughput process for DSSCs.     

Morphological characterization of aluminum-doped zinc oxide nanomaterials (AZO) for dye-sensitized solar cells

In this work, aluminum-doped ZnO (AZO, Al:ZnO) nanocomposite materials were prepared by a simple hydrothermal method using the microwave oven. Zinc oxide nanostructures were doped with aluminum in different dopant concentrations (0.5%, 1.0%, 1.5% and 2.0%). AZO materials were analyzed using XRD, SEM and EDX measurements. Also dye-sensitized solar cell (DSSC) performances of AZOs were investigated. The scanning electron microscopy (SEM) analysis confirms that the synthesized AZO nanomaterials were nanorods and nanoplates in shape and have 200 nm to 974 nm sizes in length and 116.1-269.5 nm in diameters (shown Figure 4-5). Dye-sensitized solar cell efficiencies are higher in 0.5% and 1% AZO nanorod materials. We have found the maximum efficiency as 1.94% for 1% doped AZO nanorod materials.     

染料敏化太阳电池中光阳极的研究进展

染料敏化太阳电池(dye-sensitized solar cell,DSC)的光阳极作为其重要的组成部分,在近些年的研究中取得了较大的进展。常用作光阳极的氧化物包括TiO2、ZnO、SnO2、Nb2O5、A12O3等,其中,TiO2因为综合性能表现突出,成为主要研究的光阳极材料。特别是TiO2纳晶薄膜的性质、形貌、结构等均会对DSC光电性能产生较大影响,其性质调节主要通过表面处理、修饰、掺杂等手段,而不同形貌纳米TiO2的研究主要表现在一维结构上,如纳米线、纳米棒等,本文就这些方面的研究情况进行简单归纳总结,分析影响电池性能的关键因素,并对如何更全面、更深入的提高DSC光电性能作简要展望。     

Enhanced performance of a dye-sensitized solar cell with an electrodeposited-platinum counter electrode

A counter electrode was prepared for a dye-sensitized solar cell (DSSC) through electrochemical deposition of mesoporous platinum on fluorine-doped tin oxide glass in the presence of a structure-directing nonionic surfactant, octaethylene glycol monohexadecyl ether (C₁₆EO₈). The DSSC fabricated with the electrochemically deposited Pt (ED-Pt) counter electrode rendered a higher solar-to-electricity conversion efficiency of 7.6%, compared with approximately 6.4% of the cells fabricated with the sputter-deposited or most commonly-employed thermal deposited Pt counter electrodes. This enhanced efficiency is attributed to the higher short-circuit photocurrent arising from the increases in the active surface area and light reflection as well as the decrease in the sheet resistance of the ED-Pt film, relative to those of the Pt films prepared by the other two deposition methods. The sputter-deposited Pt film yielded almost the same photovoltaic characteristics as the thermal deposited Pt film. The Pt films were characterized by FE-SEM, AFM, cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, sheet resistance measurements, adhesion tests, and light reflection tests.     

Polyvinyl pyrrolidone aided preparation of TiO2 films used in flexible dye-sensitized solar cells

Polyvinyl pyrrolidone (PVP) is introduced to low temperature preparation of a good quality TiO₂ film used in flexible dye-sensitized solar cells (DSSCs). The samples are characterized by scanning electron microscopy and UV–vis absorption spectra, the photovoltaic performance of the DSSC is measured. It is found that PVP can improve the dispersion of TiO₂ particles and the adherence of TiO₂ particles to flexible substrate, as well as the adsorption of sensitized dye to TiO₂ film. Additionally, ultraviolet light irradiation can eliminate organics remained on the surface the TiO₂ film and improve the surface state of TiO₂ film. Under an optimal condition, a flexible DSSC using TiO₂ film doped PVP and UV irradiation treated achieves a light-to-electric energy conversion efficiency of 3.02% under irradiation with a simulate solar light intensity of 100 mW cm⁻².     

Enhancement of the photoelectric performance of dye-sensitized solar cells using Ag-doped TiO<Subscript>2</Subscript> nanofibers in a TiO<Subscript>2</Subscript> film as electrode

For high solar conversion efficiency of dye-sensitized solar cells [DSSCs], TiO₂ nanofiber [TN] and Ag-doped TiO₂ nanofiber [ATN] have been extended to be included in TiO₂ films to increase the amount of dye loading for a higher short-circuit current. The ATN was used on affected DSSCs to increase the open circuit voltage. This process had enhanced the exit in dye molecules which were rapidly split into electrons, and the DSSCs with ATN stop the recombination of the electronic process. The conversion efficiency of TiO₂ photoelectrode-based DSSCs was 4.74%; it was increased to 6.13% after adding 5 wt.% ATN into TiO₂ films. The electron lifetime of DSSCs with ATN increased from 0.29 to 0.34 s and that electron recombination was reduced.     

Selenization treatment on Ag8SnSxSe6-x counter electrode of dye-sensitized solar cells in improving its electron transfer and electrocatalytic activity

In this paper, Ag₈SnS₆ powder was synthesized by the one-pot method, then prepared into Ag₈SnS₆ and Selenization treated Ag₈SnS_xSe_6-x thin films. The effects brought by the amounts of added Se powder during the annealing process on the product phases, structures, and morphologies are characterized, and the electrochemical property and the cell efficiency as assembled into the counter electrode (CEs) for dye-sensitized solar cells (DSSCs) were investigated. It showed Se into the Ag₈SnS₆ lattice occupied the site of S to transform into Ag₈SnS_xSe_6-x. And the thin film also became unflatten since the particles became larger after Se doping. The cell efficiency of Ag₈SnS_xSe_6-x CEs reached 4.26%, which was increased by 28.31% compared to that of Ag₈SnS₆ CEs. Ag₈SnS_xSe_6-x CEs performed lower charge transfer resistance (Rct) and (△EPP), and an increased△E value between the conduction band level of CEs and the redox potential of electrolyte. After 10 cycles, the almost unchanged cathode/anode current density implied the Ag₈SnS_xSe_6-x CEs received good structure stability. Selenization treatment was able to facilitate electron transport and enhance the electrocatalytic activity, and as expected to be a promising method in improving the performance of the DSSCs.