Multifunctional interface modification of energy relay dye in quasi-solid dye-sensitized solar cells.
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ABSTRACT:
SUBMITTER: Gao R
PROVIDER: S-EPMC4081872 | biostudies-other | 2014
REPOSITORIES: biostudies-other
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Project description:We discovered a method of applying a forward pulsed bias to recover the degraded quasi-solid-state dye-sensitized solar cells (DSSCs). Up to 30.7% of the power conversion efficiency (?) of a degraded poly(vinylidene fluoride) (PVDF) based DSSC was recovered by a double-pulse. The recovered ? remained higher than that before the double-pulse treatment for at least 28 days. It is deduced that the blocking of ion-transport channels in the quasi-solid-state electrolyte causes degradation of the DSSCs. This study will shed light on the efficiency enhancement and long-term stability of quasi-solid-state DSSCs.
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Project description:This work contributes to combining 12.2 mM purified anthocyanin of cyanidin-3-glucoside extracted from Indonesian black rice as the natural pigment with a ruthenium photosensitizer (1 : 1) in dye-sensitized solar cells (DSSCs) in liquid and quasi solid-state electrolytes. The findings essentially highlight the spectroscopic and electron transfer mechanism for the future trend of D-π-A natural pigment modification. The complete pigment comparison, dye absorbance, dye adsorption onto the semiconductor, dye electronic properties, electron excitation, and regeneration were investigated using spectroscopic methods. Cells employ TiO2 mesoporous nanoparticles (19.18 nm grain size, 50.99 m2 g-1 surface area, 87.8% anatase 12.2% rutile, 10.58 μm thickness, 3.18 eV band gap) sensitized by anthocyanin-N719 photosensitizer (12.2 mM) with the I-/I3 - electrolyte (0.1 M lithium iodide/0.05 M iodine/0.6 M 1-buty-3-methylimidazolium iodide/0.5 M 4-tert-butylpyridine/polyethylene oxide M w = 1 × 106) - Pt film. As a result, the quasi-solid state with combined anthocyanin-ruthenium dye-sensitized solar cell (3.51%) is achieved and reported for the first time. The work also achieved the highest efficiency of the anthocyanin dye-sensitized quasi-solid state solar cells of 2.65%. The insight on how the combined anthocyanin-N719 and the quasi-solid state electrolytes exhibit better performances will be further discussed.
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Project description:This report is to address the question if black γ-polymorph of cesium tin tri-iodide (B-γ-CsSnI3) can be used as a solid-state hole-transport material in the conventional DSSCs with the N719 dye to replace the liquid electrolyte as reported by I. Chung et al. on Nature 485, 486, (2012). Here we demonstrate rigorously that B-γ-CsSnI3 is not energetically possible to collect photogenerated holes because of the large energy barrier at the interface of N719/B-γ-CsSnI3. Therefore, it cannot serve as a hole-transporter for the conventional DSSCs although it is a good hole-conducting material. A solution-based method was employed to synthesize the B-γ-CsSnI3 polycrystalline thin-films used for this work. These thin-films were then characterized by X-ray diffraction, Hall measurements, optical reflection, and photoluminescence (PL). Particularly, spatially resolved PL intensity images were taken after B-γ-CsSnI3 was incorporated in the DSSC structure to insure the material integrity. The means of ultraviolet photoemission spectroscopy (UPS) was used to reveal why B-γ-CsSnI3 could not act as the substitute of liquid electrolyte in the conventional DSSCs. For the completeness, other two related compounds, one is the yellow polymorph of CsSnI3 and other is Cs2SnI6 with tetravalent tin instead of double-valent tin in CsSnI3 were also investigated by UPS.
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Project description:This work is a pioneer attempt to fabricate quasi-solid dye-sensitized solar cell (QSDDSC) based on organosoluble starch derivative. Rheological characterizations of the PhSt-HEC blend based gels exhibited viscoelastic properties favorable for electrolyte fabrication. From amplitude sweep and tack test analyses, it was evident that the inclusion of LiI improved the rigidity and tack property of the gels. On the other hand, the opposite was true for TPAI based gels, which resulted in less rigid and tacky electrolytes. The crystallinity of the gels was found to decline with increasing amount of salt in both systems. The highest photoconversion efficiency of 3.94% was recorded upon addition of 12.5 wt % TPAI and this value is one of the highest DSSC performance recorded for starch based electrolytes. From electrochemical impedance spectroscopy (EIS), it is deduced that the steric hindrance imposed by bulky cations aids in hindering recombination between photoanode and electrolyte.
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Project description:Dye-sensitized solar cells (DSSCs) are useful devices in converting renewable solar energy into electrical energy. In DSSCs, the triiodide reduction at the surface of TiO2 is one of the detrimental processes that limit the realization of high efficiencies of the device. To alleviate the active sites available on the semiconductor surface for this detrimental process, the interfacial modification of the dye-adsorbed TiO2|electrolyte interface has been attempted by coadsorption of oleic acid (OA) over the TiO2 surface. Thus, the modified cell exhibited a higher efficiency (η) of 12.9% under one sun illumination when compared with that of the unmodified cell (η = 11.1%). To provide an insight into the OA anchoring and dynamics of electron transport at the photoanode|electrolyte interface, molecular spectroscopic and electrochemical impedance spectroscopic analyses were carried out. A red shift in the optical absorption spectrum was observed after the addition of OA to dye-adsorbed TiO2. The binding of OA to TiO2 surface was found to be through bridging bidentate type. Mott-Schottky analyses of the DSSCs under dark conditions were made to probe the shift in the Fermi level of TiO2 upon OA modification. In addition, the Förster resonance energy transfer (FRET) has been found between OA and N719 dye. Thus, the red shift in the optical absorption, enhanced electron-transfer kinetics, and FRET contributes to the observed enhancement in the efficiency of the device containing OA-modified photoanode.
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Project description:The dye-sensitized solar cell (DSSC) is a potential alternative to the widely used Si-based solar cell, with several advantages including higher energy conversion efficiency under weak and indirect illumination conditions, and the possibility of practical application in urban life due to their exterior characteristics. However, despite these advantages, the energy conversion efficiency of DSSCs has remained low at ∼10%. To improve the efficiency of DSSCs, research has been done on modifying the materials used in DSSC component parts, such as the photoanode, electrolyte, and counter electrode. Another approach is to modify the photoanode to increase the diffusion coefficient, reduce the recombination rate, and enhance the light behavior. One of the most popular methods for improving the efficiency of DSSCs is by trapping and dispersing the incident light using a scattering layer. Use of a scattering layer has shown various and interesting results, depending on the application, but it is currently used only in a simple form and there has been no deep research on the further potential of the scattering layer. In this study, the scattering center was introduced to maximize the effect of scattering. Light distribution near the scattering center, within or on the photoanode, was investigated using finite differential time domain (FDTD) numerical methods. Based on the FDTD analysis, an optimized, dome-shaped three-dimensional modified structure of a transparent photoanode with minimized scattering centers was introduced and indicated the possibility of modifying the photon distribution in the photoanode to enhance the performance of DSSCs. In addition to using the scattering center, we have introduced the structure of the dome-shaped three-dimensional structure to utilize the light distribution within the photoanode. This novel three-dimensional transparent photoanode and scattering center design increased the energy conversion efficiency of DSSCs from 6.3 to 7.2%. These results provide a foundation for investigating the role of the scattering center via further in-depth research. This new three-dimensional photoanode design provides a means to overcome the previous limitations on DSSC performance.
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Project description:Electrospun nanocomposite polymer blend poly(vinylidene difluoride-co-hexafluoropropylene) (PVDF-HFP)/poly(methyl methacrylate) (PMMA) membranes with a novel dispersion of x wt % of one-dimensional (1D) TiO2 nanofiber fillers (x = 0.0-0.8 in steps of 0.2) were developed using the electrospinning technique. The developed nanocomposite polymer membranes were activated using various redox agents such as LiI, NaI, KI, and tetrabutyl ammonium iodide (TBAI). Introduction of the 1D TiO2 nanofiber fillers improves the amorphous nature of the blended polymer membrane, as confirmed through X-ray diffraction (XRD) and Fourier transform infrared (FTIR), and yielded an electrolyte uptake of over 480% for a 6 wt % TiO2 nanofiber filler-dispersed sample. PVDF-HFP/PMMA-1D 6 wt % TiO2 nanofiber fillers with the LiI-based redox electrolyte provided a high conductivity of 2.80 × 10-2 S cm-1 and a power conversion efficiency (PCE) of 8.08% to their fabricated dye-sensitized solar cells (DSSCs). The observed better ionic conductivity and efficiency of the fabricated DSSCs could be due to the faster movement of the smaller-ionic-radius (Li) ions entrapped inside the amorphous polymer. This enhanced mobility of ions in the quasi-solid electrolyte leads to faster regeneration of the depleting electrons in the photoanode, resulting in improved efficiency. Further, the achieved high conductivity was analyzed in terms of the dynamics and relaxation mechanisms involved by the ionic charge carriers with complex impedance spectroscopy using a random barrier model and Havriliak-Negami formulation. It was observed that the high-conducting PVDF-HFP/PMMA-1D 6 wt % TiO2 nanofiber fillers with LiI-based redox electrolyte show better ac conductivity parameters such as a σ of 5.82 × 10-2 S cm-1, ωe (12685 rad s-1), τe (0.909 × 10-4 s), and n (0.578). Also, dielectric studies revealed that the high-conducting sample has a higher dielectric constant and subsequently high loss. The J-V characteristics were studied using the equivalent circuit of a single-diode model, and the parameters influencing the photovoltaic performance were determined by Symbiotic Organisms Search (SOS) algorithm. The results suggest that the high-efficient sample possesses a minimum series resistance of 1.33 Ω and a maximum shunt resistance of 997 Ω. Hence, the highest-conducting electrospun-blended polymeric nanocomposite (PVDF-HFP-PMMA-6 wt % TiO2 nanofiber fillers) with LiI-based redox agent and tert-butyl pyridine (TBP) additive as the polymer quasi-solid electrolyte nanofibrous membrane can be a better electrolyte for high-performance dye-sensitized solar cell applications.
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Project description:BackgroundDye-sensitized solar cells (DSSCs) have garnered a lot of attention in recent years. The solar energy to power conversion efficiency of a DSSC is influenced by various components of the cell such as the dye, electrolyte, electrodes and additives among others leading to varying experimental configurations. A large number of metal-based and metal-free dye sensitizers have now been reported and tools using such data to indicate new directions for design and development are on the rise.DescriptionDSSCDB, the first of its kind dye-sensitized solar cell database, aims to provide users with up-to-date information from publications on the molecular structures of the dyes, experimental details and reported measurements (efficiencies and spectral properties) and thereby facilitate a comprehensive and critical evaluation of the data. Currently, the DSSCDB contains over 4000 experimental observations spanning multiple dye classes such as triphenylamines, carbazoles, coumarins, phenothiazines, ruthenium and porphyrins.ConclusionThe DSSCDB offers a web-based, comprehensive source of property data for dye sensitized solar cells. Access to the database is available through the following URL: www.dyedb.com .
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Project description:We demonstrate highly efficient energy harvesting devices for dim-light application under 200 lux irradiation using dye-sensitized solar cells (DSCs) and perovskite solar cells (PSCs). The high-efficiency DSCs are composed of cobalt-based redox mediators in 3-methoxypropionitrile (MPN) solvent with MK-2 sensitizer. With the introduction of under layer treatment and fine-tuning of compositions in cobalt-based electrolyte, the power conversion efficiency of cobalt-based DSCs achieves 16.0% under 200 lux illumination. That outperforms the best device using the conventional iodine-based electrolyte illuminated with the same light intensity. Especially, cobalt-based electrolyte system exhibits a higher open circuit voltage than iodine-based electrolyte counterpart. We also investigate perovskite solar cells under dim-light condition. PSCs show higher open circuit voltage and short circuit current density than DSCs with efficiency up to 23.4%. In this work, our results demonstrate the promising potential of DSCs and PSCs in the dim-light applications.
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