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1.
We report preparation and improvement in photovoltaic performance of N719-based dye-sensitized solar cells (DSSCs) using pressurized carbon dioxide (CO2) as a co-solvent for the absorption process on the TiO2 photoelectrode surface. Effective absorption of the N719 molecules on the TiO2 surface was achieved using CO2 processing, and the absorption time was shortened drastically from 24 h (in the dip process) to less than 3 h. The cells prepared under pressurized CO2 for the absorption showed greater photovoltaic performance, especially higher short-circuit current density and conversion efficiency, compared with that from typical dip method. It was revealed that the suitable CO2 pressure for the absorption was 5 MPa and the efficiency was achieved to be more than 7.5 %. Prevention of back electron transfer reactions from TiO2 to oxidized dyes or iodides was caused currently, because the homogeneous coverage of N719 molecules on the TiO2 surface was obtained by the use of pressurized CO2.  相似文献   

2.
Clean and cheap device, namely dye-sensitized solar cells (DSSCs) were fabricated using a natural dye extracted from Sambucus ebulus. We prepared five sample solutions with various pH in the extraction process to improve power conversion efficiency. The UV–visible absorption investigation of sample solutions and on photoanode show the dyes from J-type aggregation on a photoanode substrate. Redox properties of all sample solutions certify thermodynamically a charge transfer from excited state to conduction band TiO2. The optical properties of various dye solutions were investigated and results showed darkness and bluish tint effect of dye solutions extracted in basic environment rather than those extracted in acidic condition. Moreover, in comparison to the basic condition, the dye solutions extracted in acidic environment were more saturated and colorimetrically less different from that one which extracted in neutral condition. Photophysical and photoelectrochemical performance of natural extraction dyes have been studied in dye-sensitized solar cell devices. The results show the rather high conversion efficiency of 0.57%, 1.15%, 1.02%, 0.35% and 0.15% of each individual dye extraction, respectively.  相似文献   

3.
Hydrothermal process has been employed to synthesize titanium oxide (TiO2) bottle brush. The nanostructured bottle brushes with tetragonal nanorods of ~75 nm diameter have been synthesized by changing the nature of the precursors and hydrothermal processing parameters. The morphological features and structural properties of TiO2 films were investigated by field emission scanning electron microscopy, X-ray diffraction, high-resolution transmission electron spectroscopy, Fourier transform Raman spectroscopy, and X-ray photoelectron spectroscopy. The influence of such nanostructures on the performance of dye-sensitized solar cells (DSSCs) is investigated in detail. The interface and transient properties of these nanorods and bottle brush-based photoanodes in DSSCs were analyzed by electrochemical impedance spectroscopic measurements in order to understand the critical factors contributing to such high power conversion efficiency. Surface area of sample was recorded using Brunauer–Emmett–Teller measurements. It is found that bottle brush provides effective large surface area 89.34 m2 g?1 which is much higher than TiO2 nanorods 63.7 m2 g?1. Such effective surface area can facilitate the effective light harvesting, and hence improves the dye adsorption and the photovoltaic performance of DSSCs, typically in short-circuit photocurrent and power conversion efficiency. A best power conversion efficiency of 6.63 % has been achieved. We believe that the present device performance would have wide interests in dye-sensitized solar cell research.  相似文献   

4.
In the present paper, photovoltaic studies of dye-sensitized solar cells (DSSCs) based on betacyanin/TiO2 and betacyanin/WO3–TiO2 have been done. The cell performances were compared through IV curves and wavelength dependant photocurrent measurements for the two new types of DSSCs. The TiO2-coated DSSC showed the photovoltage and photocurrent of 300 mV and 4.96 mA/cm2, whereas the cell employing WO3–TiO2 photoelectrode showed the values 435 mV and 9.86 mA/cm2, respectively. The conversion efficiency of TiO2 based dye-sensitized solar cell was found to be 0.69 %, while WO3–TiO2-based cell exhibited a higher conversion efficiency of 2.2 %. The better performance of the WO3–TiO2 dye-sensitized solar cell photoelectrode is thought to be due to an inherent energy barrier at the electrode/electrolyte interface leading to the reduced recombination of photoinduced electrons.  相似文献   

5.
The ZnO nanowire (NW) array/TiO2 nanoparticle (NP) composite photoelectrode with controllable NW aspect ratio has been grown from aqueous solutions for the fabrication of dye-sensitized solar cells (DSSCs), which combines the advantages of the rapid electron transport in ZnO NW array and the high surface area of TiO2 NPs. The results indicate that the composite photoelectrode achieves higher overall photoelectrical conversion efficiency (η) than the ZnO NW alone. As a result, DSSCs based on the ZnO NW array/TiO2 NP composite photoelectrodes get the enhanced photoelectrical conversion efficiency, and the highest η is also achieved by rational tuning the aspect ratio of ZnO NWs. With the proper aspect ratio (ca. 6) of ZnO NW, the ZnO NW array/TiO2 NP composite DSSC exhibits the highest conversion efficiency (5.5 %). It is elucidated by the dye adsorption amount and interfacial electron transport of DSSCs with the ZnO NW array/TiO2 NP composite photoelectrode, which is quantitatively characterized using the UV-Vis absorption spectra and electrochemical impedance spectra. It is evident that the DSSC with the proper aspect ratio of ZnO NW displays the high dye adsorption amount and fastest interfacial electron transfer.  相似文献   

6.
Zinc oxide carbon nanotube (ZnO-CNTs) thin films were prepared by a chemical bath deposition (CBD) method and immersed in N719 dye for 24 h. The structure and surface morphology of the samples was captured by X-ray diffraction (XRD) and field effect scanning electron microscopy (FESEM) unit, respectively. The photovoltaic properties of ZnO- and ZnO-CNT-based dye-sensitized solar cells (DSSCs) were measured by considering the power conversion efficiency (η), photocurrent density (J sc), open-circuit voltage (V oc), and fill factor (FF). The cell's efficiency doped with single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) reached 0.65 and 0.28 %, respectively. ZnO-based DSSC generated only η?=?0.003 %. The electrochemical impedance spectroscopy (EIS) unit was employed to investigate the electron transport properties such as effective electron lifetime (τ eff), effective electron chemical diffusion coefficient (D eff), and effective electron diffusion length (L n ). The addition of CNTs has enhanced the photovoltaic properties of the DSSCs and reduced the recombination effect inside the solar cell.  相似文献   

7.
《Current Applied Physics》2015,15(3):307-312
We have employed several natural dyes for application in dye sensitized solar cells (DSSC). Spinach, beet, red cabbage and strawberry are well known and have been already used. We then checked the opportunity to realize good DSSC with dyes available in Tunisia: Henna and Mallow (Mloukhya). Henna is a herb which has interesting reddish brownish dyeing properties used since antiquity for traditional decoration of skin, hair and fingernails in the Middle East and North Africa. The mallow is a green vegetable which is widely consumed in the same region. The optical absorption of the extracted dyes diluted in ethanol or distilled water were measured using UV–Vis spectrophotometer. The absorption in beet and red cabbage is more significant compared to the other dyes. Mallow and henna dyes present a noticeable band in the region 660 nm. Infra-red spectroscopy measurements were done to probe the structure and dynamics in our used dyes. In this paper, we present the steps followed in the making of our solar cells. The DSSC were assembled using two glass plates (supporting electrode and counter electrode) which are coated with transparent conducting oxide (TCO). The counter electrode is coated by a catalyst Pt (Platinum) to speed up the redox reaction with the electrolyte solution. The typical J–V curves of our solar cells under AM 1.5 using a density of power 100 mW/cm2 were measured. Cells using henna and mallow as dyes present less degradation with time in the photoelectric characteristics. The mallow cell shows a good fill factor of 55% and a noticeable photoelectric conversion efficiency of 0.215%.  相似文献   

8.
Post deposition treatment (PDT) for Cu2ZnSn(S,Se)4 (CZTSSe) was carried out by simply dipping the absorber into the KF solution at 80 °C. The dipping time of absorber in KF solution was found to be crucial to device parameters of CZTSSe solar cell. The K-doping improved the solar cell efficiency from 4.4% to 7.6% by 1 min dipping whereas the longer than 5 min dipping solar cells showed distorted kink J-V curves. The activation energy of CZTSSe solar cell was increased upto 1 min KF treatment from 0.83 eV to 0.92 eV which indicates interface recombination is reduced significantly. However, the activation energies of 5 min and 10 min dipping solar cells were found to be 0.81 eV and 0.63 eV where dominant recombination was interface recombination. Furthermore, trap energies of 49 meV and 298 meV of pristine CZTSSe solar cell were modified to 33 meV and 117 meV for 1 min treated CZTSSe solar cell. Trap energies of 5 min were calculated to be 112 meV and 147 meV. The proper KF doping passivated the shallow as well as deep defects of CZTSSe solar cell which is reflected in photovoltaic performances directly.  相似文献   

9.
Titania (TiO2) nanorods have been synthesized with controlled size for dye-sensitized solar cells (DSSCs) via hydrothermal route at low hydrothermal temperature of 100 °C for 24 h. The titania nanorods were characterized using XRD, SEM, TEM/HRTEM, UV-vis Spectroscopy, FTIR and BET specific surface area (S BET), as well as pore-size distribution by BJH. The results indicated that the bulk traps and the surface states within the TiO2 nanorods films have enhanced the efficiency of DSSCs. The size of the titania nanorods was 6.7 nm in width and 22 nm in length. The high surface area can provide more sites for dye adsorption, while the fast photoelectron-transfer channel can enhance the photogenerated electron transfer to complete the circuit. The specific surface area S BET was 77.14 m2?g?1 at the synthesis conditions. However, the band gap energy of the obtained titania nanorods was 3.2 eV. The oriented nanorods with appropriate lengths are beneficial in improving the electron transport property and thus leading to the increase of photocurrent, together enhancing the power conversion efficiency. A nearly quantitative absorbed photon-to-electrical current conversion achieved upon excitation at wave length of 550 nm and the power efficiency was enhanced from 5.6 % for commercial TiO2 nanoparticles Degussa (P25) cells to 7.2 % for TiO2 nanorods cells under AM 1.5 illumination (100 mW?cm?2). The TiO2 cells performance was improved due to their high surface area, hierarchically mesoporous structures and fast electron-transfer rate compared with the Degussa (P25).  相似文献   

10.
In this paper, TiO2 particles (~30 nm) modified with Gd2O3-coating layer (~2 nm) for dye-sensitized solar cells (DSSCs) were fabricated via the hydrothermal method. Among the solar cells based on the Gd3+-doped TiO2 photoanodes, the optimal conversion efficiency was obtained from the 0.025Gd3+-modified TiO2-based cell, with a 17.7% improvement in the efficiency as compared to the unmodified one (7.18%). This enhancement was probably due to the improved UV radiation harvesting via a down-conversion luminescence process by Gd3+ ions, enhancement of visible light absorption and improved dye loading capacity. In addition, after Gd modification, a thin coating could be formed on the TiO2 nanoparticles, which worked as an energy barrier and resulted in a lower charge recombination.  相似文献   

11.
A simple and high efficient reduced graphene oxide/acetylene black (rGO/ACET) nano-composite electrode was prepared as the substitute of high-cost Pt counter electrode in dye-sensitized solar cells (DSSCs). Surface-modified method called solvent-substituting (SS) was firstly used to avoid agglomeration of rGO sheets. The Brunner-Emmet-Teller (BET)-specific surface area of rGO was increased from 195.823 to 355.210 m2/g after modifying with ethanol. Then ACET particles were introduced between rGO layers to improve the electronic transportation properties. The chemical compositions, microstructures, and pore size distributions of rGO/ACET composites were investigated. Electrochemical impedance spectroscopy (EIS) indicated that rGO/ACET counter electrode had a lower charge transfer resistance (Rct) and its S-shaped current–voltage curves disappeared obviously. The highest power conversion efficiency up to 6.62% was achieved for the DSSCs with rGO/ACET nano-composite counter electrode.  相似文献   

12.
We present a new method of synthesizing ZnO/TiO2 core–shell nanowire (NW) arrays for the fabrication of dye-sensitized solar cells (DSSCs). Vertically aligned ZnO NW arrays were obtained on Si substrates, and modified by a TiO2 shell in order to solve the recombination problems via a cost-effective spin-coating method. The structure of the ZnO/TiO2 composite NW arrays was characterized. The experimental results indicate that the TiO2 shell enhances the performance of the DSSCs, through improving the stability of the ZnO NWs and decreasing the recombination of photogenerated electrons on the NW surface. The highest overall conversion efficiency of the cell reaches about 3.0 %.  相似文献   

13.
Shu-Dan Li  Ting Li  Chen-Yi Wang  Kun Gao 《Ionics》2016,22(12):2331-2339
Li2CO3 modified carbon microbead composites (LCO/CMB-T) with different covering amount are prepared by solvent evaporation and dipping method. LiCH3COO are first used as lithium source, which can provide a precise control of Li2CO3 amount through varying dipping times or solution concentration. The morphology, structure, and covering amount are characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), and atomic absorption spectrometer (AAS). The dipping process can produce the samples with better surface coverage, more uniform coating, and higher Li2CO3 crystallinity, while the appropriate amount of Li2CO3 can help to decrease initial irreversible capacity and improve cell performance. Here, the sample with 1.07 % Li2CO3 prepared by dipping method shows the highest initial discharge capacity of 353.7 mAh g?1 and coulombic efficiency of 89.5 %. The capacity retention is up to 82.1 % after 30 cycles.  相似文献   

14.
Plasmonic metal nanoparticles have shown great promise in enhancing the light absorption of organic dyes and thus improving the performance of dye-sensitized solar cells (DSSCs). However, as the plasmon resonance of spherical nanoparticles is limited to a single wavelength maximum (e.g., ~ 520 nm for Au nanoparticles), we have here utilized silica-coated gold nanorods (Au@SiO2 NRs) to improve the performance at higher wavelengths as well. By adjusting the aspect ratio of the Au@SiO2 NRs, we can shift their absorption maxima to better match the absorption spectrum of the utilized dye (here we targeted the 600–800 nm range). The main challenge in utilizing anisotropic nanoparticles in DSSCs is their deformation during the heating step required to sinter the mesoporous TiO2 photoanode and we show that the Au@SiO2 NRs start to deform already at temperatures as low as 200 °C. In order to circumvent this problem, we incorporated the Au@SiO2 NRs in a TiO2 nanoparticle suspension that does not need high sintering temperatures to produce a functional photoanode. With various characterization methods, we observed that adding the plasmonic particles also affected the structure of the produced films. Nonetheless, utilizing this low-temperature processing protocol, we were able to minimize the structural deformation of the gold nanorods and preserve their characteristic plasmon peaks. This allowed us to see a clear redshift of the maximum in the incident photon-to-current efficiency spectra of the plasmonic devices (Δλ ~ 14 nm), which further proves the great potential of utilizing Au@SiO2 NRs in DSSCs.
Graphical Abstract Undeformed gold nanorods provide an enhanced performance of dye-sensitized solar cells at high wavelengths
  相似文献   

15.
ZnO nano-network structures with high porosity were prepared for use in the photoelectrodes of binder-free dye-sensitized solar cells (DSSCs) by DC sputtering and subsequent thermal oxidation. Zn thin films prepared at 100 °C showed nano-network structures with high porosity, while those prepared at 25 °C did not. This was partially attributed to the high mobility of sputter-deposited particles that arrived at the surface of the substrate and partially to a supersaturation mechanism. The prepared nano-network Zn was successfully transformed to ZnO without a morphological change via subsequent annealing in air. The power conversion efficiency of DSSCs based on the ZnO nano-network structures exhibited 10 times higher efficiency than those based on ZnO film prepared at 25 °C because of its large surface area for adsorption of dye molecules. The thickness of the ZnO nano-network structures increased linearly at 10 μm h?1 as a function of sputter time. As the film thickness increased, the power conversion efficiency of DSSCs increased from 1.09% to 1.82%.  相似文献   

16.
Developing efficient and cost-effective photoanode plays a vital role determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Here, we demonstrate DSSCs that achieve relatively high power conversion efficiencies (PCEs) by using one-dimensional (1D) zinc oxide (ZnO) nanowires and copper (II) oxide (CuO) nanorods hybrid nanostructures. CuO nanorod-based thin films were prepared by hydrothermal method and used as a blocking layer on top of the ZnO nanowires’ layer. The use of 1D ZnO nanowire/CuO nanorod hybrid nanostructures led to an exceptionally high photovoltaic performance of DSSCs with a remarkably high open-circuit voltage (0.764 V), short current density (14.76 mA/cm2 under AM1.5G conditions), and relatively high solar to power conversion efficiency (6.18%) . The enhancement of the solar to power conversion efficiency can be explained in terms of the lag effect of the interfacial recombination dynamics of CuO nanorod-blocking layer on ZnO nanowires. This work shows more economically feasible method to bring down the cost of the nano-hybrid cells and promises for the growth of other important materials to further enhance the solar to power conversion efficiency.  相似文献   

17.
《Current Applied Physics》2014,14(6):856-861
TiO2 nanofibers (NFs) were fabricated by an electrospinning process and were used as scattering layers in dye-sensitized solar cells (DSSCs). The NF-coated photoanodes of the DSSCs were prepared with a variety of scattering layer thicknesses. The thickness effect of the scattering layer on the double-layered TiO2 nanoparticle (NP)/TiO2 NF structure was investigated through structural, morphological, and optical measurements. In the double-layered photoanode, the TiO2 NP layer plays a major role in dye adsorption and light transmission, and the TiO2 NF scattering layer improves the absorption of visible light due to the light scattering effects. The scattering effect of TiO2 NFs layer was examined by the incident monochromatic photon-to-electron conversion efficiency (IPCE) and UV–Vis spectrometry. The conversion efficiency for the 12 μm-thick photoanode composed of a 2 μm-thick TiO2 NF layer and 10 μm-thick TiO2 NP layer was higher than that of DSSCs with only TiO2 NPs photoanode by approximately 33%.  相似文献   

18.
Silicon (Si) nanoparticles with average size of 13 nm and orange–red luminescence under UV absorption were synthesized using electrochemical etching of silicon wafers. A film of Si nanoparticles with thickness of 0.75 µm to 2.6 µm was coated on the glass (TiO2 side) of a dye‐sensitized solar cell (DSSC). The cell exhibited nearly 9% enhancement in power conversion efficiency (η) at film thickness of ~2.4 µm under solar irradiation of 100 mW/cm2 (AM 1.5) with improved fill factor and short‐circuit current density. This study revealed for the first time that the Si‐nanoparticle film converting UV into visible light and helping in homogeneous irradiation, can be utilized for improving the efficiency of the DSSCs. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

19.
The solar cell performance of the black dye, N719 dye and the cocktail of two dyes on TiO2 films were studied by mean of the utilization as light harvesting electrodes in solid-state FTO|TiO2|dye|CuI|Cr–FTO cells. The power conversion efficiencies of 3.8% and 3.0% are obtained when N719 and black dye were used. When the mixture of 1:1 of two dyes was used, the conversion efficiency rises to 4.6%. In the mixture of N719 and black dye, the N719 dye acts as the aggregation preventer and a co-absorber on TiO2 surfaces. The increased absorption of light by the two dyes results in increase of electron injection thus enhancing both the short-circuit current density and the open circuit voltage contributing to increased power conversion efficiency of the cell.  相似文献   

20.
We investigate the influence of the pyrazole content on the polyvinylidene fluoride (PVDF)/KI/I2 electrolytes for dye-sensitized solar cells (DSSCs). The solid polymer electrolyte films consisting of different weight percentage ratios (0 20, 30, 40, and 50 %) of pyrazole doped with PVDF/KI/I2 have been prepared by solution casting technique using N,N-dimethyl formamide (DMF) as a solvent. The as-prepared polymer electrolyte films were characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR spectroscopy), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), alternate current (AC)-impedance analysis, and scanning electron microscopy (SEM). The 40 wt% pyrazole-PVDF/KI/I2 electrolyte exhibited the highest ionic conductivity value of 9.52?×?10?5 Scm?1 at room temperature. This may be due to the lower crystallinity of PVDF and higher ionic mobility of iodide ions in the electrolyte. The DSSC fabricated using this highest ion conducting electrolyte showed an enhanced power conversion efficiency of 3.30 % under an illumination of 60 mW/cm2 than that of pure PVDF/KI/I2 electrolyte (1.42 %).  相似文献   

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