染料敏化太阳能电池的非金属有机敏化剂

染料敏化太阳能电池(DSSC)是一种新型的太阳能电池,综述了DSSC的非金属有机染料敏化剂的研究现状,分析了各类敏化剂的结构与电池的能量转换效率的关系,并提出非金属有机染料结构的设计思路。     

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.     

Theoretical study of indoline dyes for dye-sensitized solar cells

Indoline dye sensitizers were designed and studied theoretically to increase molar extinction coefficients in the visible to near infrared region for solar-cell devices. To gain insight into dye sensitizers' structural, electronic, and optical properties, DFT/TDDFT calculations were performed on a series of dye sensitizers derived from the D149. The good agreement between the experimental and TDDFT calculated absorption spectra of the D149 sensitizer allowed us to provide a detailed assessment of the main spectral features of a series of dye sensitizers. Increase in the conjugation length resulted in a more red-shifted spectral response and less positive oxidation potential than that of the D149. The dye with the dimethylfluorene group showed stronger absorption bands due to a large dipole moment. The calculated dipoles for the dye series correlate well with the observed strong absorption bands of the electronic spectra. These results provided useful clues for the molecular engineering of efficient organic dye sensitizers.     

Solid-state dye-sensitized solar cells based on ordered ZnO nanowire arrays

A solid-state dye-sensitized solar cell (DSC) is fabricated by using arrays of 11-12 μm long, vertically oriented ZnO nanowires as the anode and CuSCN as the solid hole-transport material. The fabricated DSC yields a remarkably higher photocurrent density (J(SC) = 8 mA cm(-2)) compared to previously reported data for solid-state DSCs based on either one-dimensional nanostructures (J(SC) = 0.34 mA cm(-2)) or nanoporous nanocrystalline structures (J(SC) = 4.5 mA cm(-2)) of ZnO. A power conversion efficiency of 1.7% under an irradiation of AM 1.5 G simulated sunlight is reported.     

Influence of donor moiety in ruthenium sensitizers on the properties of dye-sensitized solar cells

Heteroleptic ruthenium complexes cis-[Ru(H2dcbpy)(L)(NCS)2], where H2dcbpy is 4,4'-dicarboxylic acid-2,2'-bipyridine and L is 4-(4-(N,N-di-(p-hexyloxyphenyl)-amino)styryl)-4'-methyl-2,2'-bipyridine (Rut-A) or 4-(4'-(3,6-dihexyloxycarbazole-9-yl)-styryl)-4'-methyl-2,2'-bipyridine (Rut-B), have been synthesized and characterized by NMR, UV-Vis spectroscopy, and cyclic voltammogram. The effect of different electron donors on the properties of dye-sensitized solar cells has been studied. The power conversion efficiency of DSSC based on Rut-B is 6.1% while Rut-A delivered a lower efficiency of 4.52% under the same device fabrication and measuring conditions. The better photovoltaic performance of Rut-B is mainly associated with enhanced dye absorptivity and charge recombination suppression.     

Enhancing the performance of dye-sensitized solar cells by ZnO nanorods/ZnO nanoparticles composite photoanode

In this paper, ZnO nanorods (NRs) were prepared by a two-step solution phase reaction. A composite photoanode architecture is fabricated by adding 0–0.20 at.% ZnO NRs into ZnO nanoparticles (NPs). The scanning electron microscopy image shows that the average diameter and length of the ZnO NRs are about 50 nm and 2–5 µm, respectively, and the ZnO NRs are uniformly embedded into the ZnO NPs photoanode. The UV–vis spectrum analysis reveals that the amount of dye adsorption of the composite photoanode decreases with increasing ZnO NRs content. Meanwhile, the influence of ZnO NRs contents on the dye-sensitized solar cells (DSSCs) performance is systematically investigated. The photocurrent density–voltage (J–V) characteristics reveal that the device performance of DSSCs can be significantly enhanced by the composite photoanode. Typically, the DSSC with 0.15 at.% ZnO NRs obtains the optimal energy conversion efficiency of 3.8%, which is 28.4% higher than that of the pristine ZnO DSSCs. The electrochemical impedance spectroscopy (EIS) analysis shows that ZnO NRs can provide a direct pathway for accelerating electron transport, extending the electron lifetime, suppressing electron recombination and improving electron collection efficiency. These results indicate that the incorporation of ZnO NRs in the photoanode is an effective way to improve the performance of DSSCs.     

Polymer electrolytes based on grafted inorganic nanoparticles for dye-sensitized solar cells

Inorganic nanoparticles such as TiO2 and SiO2 were grafted with poly(oxyethylene methacrylate) (POEM) and blended with poly(ethylene glycol) (PEG), 1-methyl-3-propylimidazolium iodide (MPII) and iodine (I2) to prepare polymer electrolytes for dye-sensitized solar cells (DSSC). The effects of the grafted nanoparticles on the coordination interactions and structures of electrolytes were investigated using FT-IR spectroscopy and differential scanning calorimetry (DSC). The energy conversion efficiencies were obtained as 3.3 and 2.9% for TiO2 and SiO2 based electrolytes, respectively. Good interfacial contact between the electrolyte and the electrodes was also confirmed by field emission scanning electron microscopy (FE-SEM).     

All-solid,flexible solar textiles based on dye-sensitized solar cells with ZnO nanorod arrays on stainless steel wires

An all-solid, flexible solar textile fabricated with dye-sensitized solar cells (DSSCs) woven into a satin structure and transparent poly(ethylene terephthalate) (PET) film was demonstrated. A ZnO nanorod (NR) vertically grown from fiber-type conductive stainless steel (SS) wire was utilized as a photoelectrode, and a Pt-coated SS wire was used as a counter electrode. A graft copolymer, i.e. poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom transfer radical polymerization (ATRP) and used as a solid electrolyte. The conditions for the growth of ZnO NR and sufficient dye loading were investigated to improve cell performance. The adhesion of PET films to DSSCs resulted in physical stability improvements without cell performance loss. The solar textile with 10 × 10 wires exhibited an energy conversion efficiency of 2.57% with a short circuit current density of 20.2 mA/cm² at 100 mW/cm² illumination, which is the greatest account of an all-solid, ZnO-based flexible solar textile. DSSC textiles with woven structures are applicable to large-area, roll-to-roll processes.     

Efficient dye-sensitized solar cells based on the combination of ZnO nanorods and microflowers

Well-aligned ZnO nanorod films were grown onto transparent conducting substrates by using an aqueous solution route. The presence of some reflections in the X-ray diffraction pattern of the ZnO films indicates the vertical alignment of the nanorods along the c axis of the wurtzite hexagonal structure. Well-aligned ZnO nanorods were observed by scanning electron microscopy. The presence of top ZnO microflower layers over the ZnO nanorod film was observed for all growth times studied. The ZnO nanorods with ZnO microflower top layers were applied as photoelectrodes in dye-sensitized solar cells. Higher photocurrent densities and photovoltages were observed with longer nanorod growth times. The high performance of the dye-sensitized solar cells might be associated to the combination of ZnO nanorods and microflowers in the same photoelectrode.     

Preparation of ZnO nanoparticles using electrodeposition and co-precipitation techniques for dye-sensitized solar cells applications

Zinc oxide thin films have been successfully prepared by co-precipitation and electrodeposition methods onto Fluorinated tin oxide substrate using zinc nitrate aqueous solutions at various bath temperatures (25–75 °C). The deposition of electrodeposition method was conducted using both using linear sweep voltammetry and Chronoamperometric techniques. The effects of solution composition, agitation and bath temperature on the electrochemical measurements and ZnO film characteristics were fully analyzed. The findings reveal that temperature and nitrate ion concentration have a strong promoting effect on ZnO film formation. Moreover, the obtained powders were investigated by X-ray diffraction, Field emission scanning electron microscopy and UV–Vis Spectroscopy. Structural characterization by X-ray diffraction indicates the formation of ZnO phase and the deposited film exhibits the Zincite structure with crystallite size around 51 nm. The photovoltaic performance of dye-sensitized solar cells based on both ZnO prepared by co-precipitation and electrodeposition methods was investigated. A power conversion efficiency (η) of 3.5 % was achieved for the DSSC with co-precipitation ZnO, which is higher than that of the cell with electrodeposition ZnO (2.5 %). Explanations are substantiated by incident photon to electron conversion efficiency curves.     

Modification of ZnO nanorods through Au nanoparticles surface coating for dye-sensitized solar cells applications

Dye-sensitized solar cells (DSSC) based on ZnO nanorods were fabricated and modified through the addition of Au nanoparticles. The as-synthesized ZnO nanorods were well-dispersed and of high crystallinity quality leading to a high cell efficiency of 5.2%. On the other hand, thick layer of Au nanoparticles aggregation may have led to distortion of plasmonic effect. Also, the addition of Au nanoparticles have effectively decreased the surface area of ZnO nanorods with direct contact to the dye molecules, resulting in a lower amount of adhered dye molecules to convert sunlight. The electrons generated by the photo-absorption through thick aggregated Au nanoparticles layer may have a lower injection rate to ZnO nanorods as compared to those absorbed by the dye.     

The effect of growth conditions on the properties of ZnO nanorod dye-sensitized solar cells

In this article, we report ZnO nanorod samples grown on transparent conductive SnO₂:F (FTO) glass substrates by two different growth routes through hydrothermal method in a closed autoclave. One route is one-step continuous growth for 10 h. The other route is discrete multi-step growth for total 48 h. In this process, fresh solution was repeatedly introduced in every step. The structural, photoluminescence (PL) and photovoltaic properties of the as-prepared nanorod arrays were investigated. The nanorod arrays obtained through multi-step growth show longer rods, higher aspect ratio, larger spacing, better crystalline quality. The PL spectrum of nanorod arrays obtained through multi-step growth shows a strong and sharp near-band-gap emission (UV) peak and a weak green-yellow emission (GY) peak (I_UV/I_GY = 7.7), which also implies its good crystallinity and high optical quality. Dye-sensitized solar cells based on ZnO nanorod arrays were fabricated, and those grown with discrete multi-step procedure present better photovoltaic properties duo to its special morphology and better crystal quality.     

ZnO hierarchical nanostructures and application on high-efficiency dye-sensitized solar cells

Uniform hierarchical ZnO nanostructures are synthesized on a large scale based on a solution approach at low temperature. The primary ZnO hexagonal prisms are firstly produced by the reaction of Zn(NO₃)₂ with hexamethylenetetramine, and then ZnO branches grow on the primary prisms by using ethylenediamine molecules as an evocator. The morphology of the hierarchical nanostructure can be controlled conveniently by adjusting the molar ratio of [EDA]/[Zn²⁺]. The hierarchical structure provides an effective pathway for carrier transport as well as larger surface area for dye adsorption, when ZnO hierarchical nanostructures serve as photoanode materials, the solar cells show higher conversion efficiency than that of primary ZnO nanowires.     

Plasmonic dye-sensitized solar cells using core-shell metal-insulator nanoparticles

We present an investigation into incorporating core-shell Au-SiO(2) nanoparticles into dye-sensitized solar cells. We demonstrate plasmon-enhanced light absorption, photocurrent, and efficiency for both iodide/triiodide electrolyte based and solid-state dye-sensitized solar cells. Our spectroscopic investigation indicates that plasmon-enhanced photocarrier generation competes well with plasmons oscillation damping with in the first tens of femtoseconds following light absorption.     

High efficiency dye-sensitized solar cells based on three-dimensional multilayered ZnO nanowire arrays with "caterpillar-like" structure

A 3D ZnO nanowire-based dye-sensitized solar cell (DSSC) with unique "caterpillar-like" structure was designed. Because of the significant improvement of the total ZnO nanowire surface area, the amount of light absorption was substantially increased. This increase in the light harvesting efficiency enables us to achieve an overall power conversion efficiency as high as 5.20%, which is the highest reported value to date for ZnO nanowire-based DSSCs. A branched-multilayered design of ZnO nanowire arrays grown from ZnO nanofiber seed layers proves to be very successful in fabricating 3D ZnO nanowire arrays. Practically, electrospun ZnO nanowires were used as the seeds in multilayer growth of ZnO nanowire arrays with a unique "caterpillar-like" structure. This unique structure significantly enhances the surface area of the ZnO nanowire arrays, leading to higher short-circuit currents. Additionally, this design resulted in closer spacing between the nanowires and more direct conduction pathways for electron transfer. Thus, the open-circuit voltage was so significantly improved as a direct result of the reduction in electron recombination.     

High-efficiency solid-state dye-sensitized solar cells based on TiO(2)-coated ZnO nanowire arrays

Replacing the liquid electrolytes in dye-sensitized solar cells (DSCs) with solid-state hole-transporting materials (HTMs) may solve the packaging challenge and improve the long-term stability of DSCs. The efficiencies of such solid-state DSCs (ss-DSCs), however, have been far below the efficiencies of their counterparts that use liquid electrolytes, primarily due to the challenges in filling HTMs into thick enough sensitized films based on sintered TiO(2) nanoparticles. Here we report fabrication of high-efficiency ss-DSCs using multilayer TiO(2)-coated ZnO nanowire arrays as the photoanodes. The straight channel between the vertically aligned nanostructures combined with a newly developed multistep HTM filling process allows us to effectively fill sensitized films as thick as 50 μm with the HTMs. The resulting ss-DSCs yield an average power conversion efficiency of 5.65%.     

Influence of defect density on the ZnO nanostructures of dye-sensitized solar cells

The relationship between bilayer nanostructure,defect density and dye-sensitized solar cell (DSCC) performances was investigated. By adjusting bilayer nanostructures,defect density of ZnO nanodendrite-nanorods structure was decreased comparing to that of nanoflowernanorods structure. The performances of DSCC based on ZnO nanodendrites-nanorods structure and nanoflowernanorods structure were studied by Raman spectrum, room
temperature photoluminescence, dye loading, photocurrent density-voltage characteristic and open-circuit voltage decay (OCVD) technique. The device with nanodendritenanorods structure has lower charge recombination rate and prolonged electron lifetime due to its microstructure feature.     

Growth of ZnO nanorods on TiO2 nanoparticles films and their application to the electrode of dye-sensitized solar cells

A ZnO nanorods (NRs)/TiO₂ nanoparticles (NPs) film has been prepared by electrochemical deposition of ZnO NRs growth on P25 TiO₂ NPs film surfaces. It was found that ZnO NRs/TiO₂ NPs could significantly improve the efficiency of dye-sensitized solar cells owing to its relatively enhanced light-scattering capability and efficient charge transport efficiency. The overall energy-conversion efficiency (η) of 3.48 % was achieved by the formation of ZnO NRs/TiO₂ NPs film, which is 33 % higher than that formed by TiO₂ NPs alone (η = 2.62 %). The charge recombination behavior of cells was investigated by electrochemical impedance spectra, and the results showed that ZnO NRs/TiO₂ NPs film has the longer electron lifetime than TiO₂ NPs alone, which could facilitate the reduction of recombination processes and thus would promote the photocatalysis and solar cell performance.