Graphene supported platinum nanoparticle counter-electrode for enhanced performance of dye-sensitized solar cells

Composites of few layered graphene (G) and platinum (Pt) nanoparticles (NP) with different loadings of Pt were used as counter electrode (CE) in dye-sensitized solar cell (DSSC). NPs were deposited directly on to G using pulsed laser ablation method (PLD). DSSCs formed using the composite CEs show improved performance compared to conventional Pt thin film electrode (Std Pt) and unsupported Pt NPs. Composite with 27% loading of Pt shows 45% higher efficiency (η = 2.9%), greater short circuit current (J(sc) = 6.67 mA cm(-2)), and open circuit voltage (V(oc) = 0.74 V) without any loss of the fill factor (FF = 58%) as compared to the cells fabricated using Std Pt electrodes. Values of η, J(sc) and V(oc) for DSSC using Std Pt CE were 2%, 5.05 mA cm(-2) and 0.68 V, respectively. Electrochemical impedance spectroscopy using I(-)(3)/I(-) redox couple confirm lower values of charge transfer resistance for the composite electrodes, e.g., 2.36 Ω cm(2) as opposed to 7.73 Ω cm(2) of Std Pt. The better catalytic activity of these composite materials is also reflected in the stronger I(-)(3) reduction peaks in cyclic voltammetry scans.     

Electroless deposition of platinum on indium tin oxide glass as the counterelectrode for dye-sensitized solar cells

A platinum (Pt) layer is electroless-deposited on indium tin oxide (ITO) glass substrate as the counterelectrode for dye-sensitized solar cells (DSSCs). Compared with other methods of depositing Pt layer, electroless deposition is simple, low-temperature, and easy to scale-up for industrial application. The Pt concentration of the electroless plating solution is found to play an important role in the cell performance. With increasing the Pt concentration, i.e. the Pt loading on the ITO surface, the resultant Pt layer exhibits a porous structure. Owing to the porous structure, the Pt layer can provide more active surface area for triiodide reduction and thus reduces the charge-transfer resistance. The cell performance is promoted accordingly with increasing the Pt concentration. Energy conversion efficiency of 6.46%, short-circuit current density of 15.04 mA cm⁻², open-circuit voltage of 0.68, and fill factor of 0.63 can be achieved for the DSSC employing electroless-Pt counterelectrode.     

Nanowire dye-sensitized solar cells

Excitonic solar cells-including organic, hybrid organic-inorganic and dye-sensitized cells (DSCs)-are promising devices for inexpensive, large-scale solar energy conversion. The DSC is currently the most efficient and stable excitonic photocell. Central to this device is a thick nanoparticle film that provides a large surface area for the adsorption of light-harvesting molecules. However, nanoparticle DSCs rely on trap-limited diffusion for electron transport, a slow mechanism that can limit device efficiency, especially at longer wavelengths. Here we introduce a version of the dye-sensitized cell in which the traditional nanoparticle film is replaced by a dense array of oriented, crystalline ZnO nanowires. The nanowire anode is synthesized by mild aqueous chemistry and features a surface area up to one-fifth as large as a nanoparticle cell. The direct electrical pathways provided by the nanowires ensure the rapid collection of carriers generated throughout the device, and a full Sun efficiency of 1.5% is demonstrated, limited primarily by the surface area of the nanowire array.     

染料敏化太阳能电池中电解质的研究进展

电解质是染料敏化太阳能电池的一个重要组成部分,是影响电池光电性能和稳定性的重要因素.电解质根据物理状态不同将其分为液体电解质、准固态电解质和固态电解质.介绍了这三种不同电解质的性能、各自的优点及存在问题,并对染料敏化太阳能电池中电解质在国内外研究发展现状进行了综述.     

Porous N-doped-carbon coated CoSe2 anchored on carbon cloth as 3D photocathode for dye-sensitized solar cell with efficiency and stability outperforming Pt

Nano Research - Photocathode with superior catalytic activity, long-term stability, and fast mass/electron transfer is highly desirable but challenging for dye-sensitized solar cell (DSC). Herein,...     

Pyreno-chalcone dendrimers as an additive in the redox couple of dye-sensitized solar cells

Novel pyreno-chalcone dendrimers 1, 2, and 3 were synthesized and their ability to act as an additive in the redox couple (I⁻/I₃ ⁻) of dye-sensitized nanocrystalline TiO₂ solar cell has been tested. The redox couple doped with pyreno-chalcone dendrimer 3 gave a short circuit photocurrent density (J _sc) of 7.40 mA/cm², open circuit voltage (V _oc) of 820 mV, and a fill factor of 0.51, corresponding to an overall conversion efficiency (η) of 7.89% under 40 mW/cm² irradiation.     

Radial electron collection in dye-sensitized solar cells

We introduce a new photoelectrode architecture consisting of concentric conducting and semiconducting nanotubes for use in dye-sensitized solar cells (DSSCs). Atomic layer deposition is employed to grow indium tin oxide (ITO) within a porous template and subsequently coat the high area photoelectrode with amorphous TiO 2. Compared with control devices lacking a current collector within the pores, the new photoelectrode geometry exhibits dramatically higher current densities, an effect attributed to the radial collection of electrons.     

Nano-TiO2 for dye-sensitized solar cells

Photovoltaics are amongst the most popular renewable energy sources and low-cost solar cell technologies are making progress to the market. Research on dye-sensitized solar cells (DSSCs) usually based on nanocrystalline TiO2 has been extensively pursued, and the number of papers and patents published in this area has grown exponentially over the last ten years. Research efforts have largely focused on the optimization of the dye, but recently the TiO2 nanocrystalline electrode itself has attracted more attention. It has been shown that particle size and shape, crystallinity, surface morphology and chemistry of the TiO2 material are key parameters to be controlled for optimized performance of the solar cell. This article will review the most recent research activities on nanostructured TiO2 for improvement of the DSSC performance.     

ZnO nanotube based dye-sensitized solar cells

We introduce high surface area ZnO nanotube photoanodes templated by anodic aluminum oxide for use in dye-sensitized solar cells (DSSCs). Atomic layer deposition is utilized to coat pores conformally, providing a direct path for charge collection over tens of micrometers thickness. Compared to similar ZnO-based devices, ZnO nanotube cells show exceptional photovoltage and fill factors, in addition to power efficiencies up to 1.6%. The novel fabrication technique provides a facile, metal-oxide general route to well-defined DSSC photoanodes.     

Electrospun carbon nanofibers as low-cost counter electrode for dye-sensitized solar cells

Electrospun carbon nanofibers (ECNs) have been explored as an electrocatalyst and low-cost alternative to platinum (Pt) for triiodide reduction in dye-sensitized solar cells (DSCs). The results of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry measurements indicated that the ECN counter electrodes exhibited low charge-transfer resistance (Rct), large capacitance (C), and fast reaction rates for triiodide reduction. Although the efficiency (η) of ECN-based cells was slightly lower than that of Pt-based cells, their short circuit current density (Jsc) and open circuit voltage (Voc) were comparable. The ECN-based cells achieved an energy conversion efficiency (η) of 5.5 % under the AM 1.5 illumination at 100 mW cm(-2). The reason for lower cell performance using the ECN electrode was because of its lower fill factor (FF) than that of Pt-based cells, probably caused by high total series resistance (RStot) at ～15.5 Ω cm2, which was larger than that of ～4.8 Ω cm2 in the Pt-based devices. Simulated results showed that the fill factor (FF) and η could be substantially improved by decreasing RStot, which might be achieved by using thinner and highly porous ECNs to reduce the thickness of the ECNs counter electrode.     

Single-crystalline zinc oxide nanowires as photoanode material for dye-sensitized solar cells

This study reports the use of single-crystalline and well-aligned ZnO nanowires as photoanode material for dye-sensitized solar cells. The ZnO nanowires are grown on fluorine-doped tin oxide coated glass substrates without catalysts by thermal evaporation. In spite of low roughness factors of around 25 for the nanowire photoanodes, the fabricated solar cells yield power conversion efficiencies of around 1.3% under AM 1.5G (100 mW cm-2) illumination. Moreover, fill factors of around 0.5 have been achieved and are relatively high when compared with reported values from ZnO nanowire photoanodes. The results reveal the advantage of using single-crystalline nanowires as photoanode material and provide clues for the advancement of nanowire based dye-sensitized solar cells.     

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.     

The effects of co-sensitization in dye-sensitized solar cells

Triazoloisoquinoline-based organic dyestuff was synthesized and used in the fabrication of dye-sensitized solar cells (DSSCs). After co-sensitization with ruthenium complex, triazoloisoquinoline-based organic dyestuff overcomes the deficiency of ruthenium dyestuff absorption in the blue part of the visible spectrum. The incident photon-to-electron conversion efficiency (IPCE) of cis-dithiocyanate-N,N′-bis-(4-carboxylate-4-tetrabutyl ammoniumcarboxylate-2,2′-bipyridine)ruthenium(II) (N719) at shorter wavelength regions (~350–500 nm) is 35 %. After addition of triazoloisoquinoline-based dyestuff for co-sensitization, the IPCE at 350–500 nm increased significantly. This can be attributed to the increased photocurrent of the cells, which improves the dye-sensitized photoelectric conversion efficiency. After optimization of the cells, an energy conversion efficiency of 8.83 % was achieved using an 12 + 4 μm TiO₂ electrode, under simulated solar illumination (AM 1.5G). As a consequence, this low molecular weight organic dyestuff is a promising candidate as a co-adsorbent and co-sensitizer for highly efficient DSSCs.     

Carbon nanotube/graphene nanocomposite as efficient counter electrodes in dye-sensitized solar cells

We demonstrated the replacement of the Pt catalyst normally used in the counter electrode of a dye-sensitized solar cell (DSSC) by a nanocomposite of dry spun carbon multi-walled nanotube (MWNT) sheets with graphene flakes (Gr-F). The effectiveness of this counter electrode on the reduction of the triiodide in the iodide/triiodide redox (I(-)/I(3)(-)) redox reaction was studied in parallel with the use of the dry spun carbon MWNT sheets alone and graphene flakes used independent of each other. This nanocomposite deposited onto fluorinated tin-oxide-coated glass showed improved catalytic behavior and power conversion efficiency (7.55%) beyond the use of the MWNTs alone (6.62%) or graphene alone (4.65%) for the triiodide reduction reaction in DSSC. We also compare the use of the carbon MWNT/Gr-F composite counter electrode with a DSSC using the standard Pt counter electrode (8.8%). The details of increased performance of graphene/MWNT composite electrodes as studied are discussed in terms of increased catalytic activity permitted by sharp atomic edges that arise from the structure of graphene flakes or the defect sites in the carbon MWNT and increased electrical conductivity between the carbon MWNT bundles by the graphene flakes.     

染料敏化太阳能电池的研究进展

综述了近年来关于染料敏化太阳能电池制备的研究状况,详细介绍了国内外关于二氧化钛薄膜、反电极、染料和电解质的设计思路及制备情况,并讨论了制备方法对太阳能电池性能的影响.     

TiO_2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%。     

Characterizations of tungsten carbide as a non-Pt counter electrode in dye-sensitized solar cells

Tungsten carbide particles as a counter electrode for dye-sensitized solar cells are prepared by heating layered tungsten oxides at 700, 800, and 900 °C. In particular, the sample heated at 800 °C reveals dominant WC structure and relatively high specific surface area. The improved photoelectrochemical properties of the sample prepared at 800 °C may be due to both catalytic activity of WC phase and high active sites for iodide reduction in comparison with other electrodes.     

Surface-oxidized tungsten for energy-storable dye-sensitized solar cells

Tungsten oxide electrodes were investigated as charge-storage materials for energy-storable dye-sensitized solar cells (ES-DSSCs). The electrochemical and structural properties of the surface-oxidized tungsten (so-WO_3 − x) and monoclinic nanocrystalline WO₃ (nc-WO₃) were studied on the difference of the charge-discharge properties. Although, the electromotive force (EMF) curve of the so-WO_3 − x was associated with structural change, the so-WO_3 − x did not show the significant structural change indicated by X-ray diffraction (XRD) patterns. On the other hand, the nc-WO₃ showed crystal transformation from monoclinic phase to tetragonal phase. The Li⁺ diffusion coefficients of the so-WO_3 − x with different Li⁺ content ratios obtained by the galvanostatic intermittent titration technique (GITT) did not fall down up to 0.3 of Li/W ratio, whereas the diffusion coefficients of nc-WO₃ decreased about two orders of magnitude in the vicinity of phase transitions. The different electrochemical properties could be explained by the less structural change of so-WO_3 − x compared with the nc-WO₃. The large-sized ES-DSSCs with the so-WO_3 − x were fabricated for the first time, and their photocharge-discharge performances were studied.     

Imine-linked receptors decorated ZnO-based dye-sensitized solar cells

This study reports the synthesis, characterization and photophysical properties of imine-linked receptors decorated ZnO nanoparticles using wet precipitation method. Initially, polymer dye 3 was synthesized using condensation reaction between 2-furancarboxaldehyde 1 and polyethylenimine 2. The decoration of imine-linked receptors on ZnO nanoparticles (sample A) was characterized and investigated by X-ray diffraction, scanning electron microscope and dynamic light scattering spectroscopic studies. Further, polymer dye 3 was added to ruthenium chloride (RuCl₃) to form a polymer–ruthenium-based composite dye-capped ZnO nanoparticles (sample B). The optical properties of sample A were evaluated by fluorescence and UV–Vis spectroscopy. The samples A and B were further processed to dye-sensitized solar cells using wet precipitation method. The results of observations revealed that the addition of ruthenium–polymer dye molecules increased the light harvesting capacity of ZnO-based DSSCs. A maximum solar power to electricity conversion efficiency (η) of 3.83% was recorded for sample B-based DSSCs with ruthenium–metal complex dye as a good photosensitizer. The recorded photovoltaic efficiency of sample B-based DSSCs was enhanced by 1.36% compared to sample A-based DSSCs.

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