Theoretical studies of photoinduced electron transfer in dye-sensitized TiO2

Department of Chemistry, University of Washington, Seattle, WA 98195, USA.
Annual Review of Physical Chemistry (Impact Factor: 15.68). 02/2007; 58:143-84. DOI: 10.1146/annurev.physchem.58.052306.144054
Source: PubMed

ABSTRACT This review describes recent research into the properties of the chromophore-TiO2 interface that forms the basis for photoinduced charge separation in dye-sensitized semiconductor solar cells. It focuses particularly on an atomistic picture of the electron-injection dynamics. The interface offers an excellent case study, pertinent as well to a variety of other photovoltaic systems, photo- and electrochemistry, molecular electronics, analytical detection, photography, and quantum confinement devices. The differences between chemists' and physicists' models for describing molecules and bulk materials, respectively, create challenges for the characterization of interfaces that include both of these components. We give an overall picture of the interface by starting with a description of the properties of the chromophores and semiconductor separately, and then by discussing the coupled system, including the chromophore-semiconductor binding, electronic structure, and electron-injection dynamics. Explicit time-dependent modeling is particularly valuable for an understanding of the ultrafast electron injection because it shows a variety of individual injection events with well-defined dynamical features that cannot be made apparent by an average reaction-rate description.

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Available from: Oleg Prezhdo, Jan 01, 2015
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    • "Dye sensitized solar cells (DSSCs) [1] [2] [3], one of the most promising environmentally friendly molecular photovoltaics, have gained immense interest over the past several decades because of their low cost, easy fabrication, flexibility and relatively high efficiency [4] [5] [6] [7]. Up to now, a record power conversion efficiency (PCE) of 13.0% has been reported recently based on the panchromatic porphyrin sensitizer and cobalt (II/III) redox shuttle [7]. "
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    ABSTRACT: The structural and electronic properties of four phenothiazine-based sensitizers (TMH-CNcis, TMH-CNtrans, TMH-COOH, and TMH-2COOH) have been examined by means of density functional theory (OFT) and time-dependent DFT calculations. And the periodic DET method is used to investigate the adsorption of dyes on the TiO2 anatase (1 0 1) surface within the DMo1(3) code. The results promise that anchor dyes with strong withdrawing CN group can effectively injected electrons to the conduction band of semiconductor TiO2 surface implying that TMH-CNcis and TMH- CNtrans will show better performance among four dyes. Particularly, the adsorption energies and charge density difference maps are calculated to investigate the possible adsorption modes of the dye on the TiO2 surface. After establishing the preferred anchoring configurations, we performed a detailed analysis on the electronic structures of the dye-TiO2 complexes to explore the absorption spectra, charge distribution and the composition of the density of states (DOS), providing a quantitative description of the variation in electronic coupling induced by the different anchoring group. The results show that after binding to the semiconductor, the absorption spectra of four dyes-TiO2 complexes are all red-shifted significantly as compared to that of the isolated dyes, and the TMH-CNtrans-TiO2 will transfer more electrons during the photoexcitation, showing an obvious charge transfer characteristic.
    Computational and Theoretical Chemistry 10/2014; 1045. DOI:10.1016/j.comptc.2014.07.008 · 1.37 Impact Factor
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    • "The above photocatalytic reactions depend on three factors: light absorption of photocatalysts, creation of charge carriers, and use of the charge carriers in the processes [30] [31] [32] [33]. The lifetime of the excited electron–hole pair is a few nanoseconds that are adequate for promoting redox reactions [12] [21]. But, the practical reaction of a bare TiO 2 as catalyst is slow to some extent due to "
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    ABSTRACT: Global warming and fuel crisis have attracted attention to using carbon dioxide (CO2) as a feedstock for preparing value-added compounds. Of particular interest in this context, we aim to review current knowledge of photocatalytic conversion of CO2 towards solar fuels over titanium dioxide (TiO2) from nanoengineering point of view. The basic principle of photocatalytic synthesis is briefly described, and then engineering design of the TiO2 photocatalysts is emphasized with respect to reaction parameters. The links between photocatalytic properties of nanostructured TiO2 and CO2 conversion by using solar energy are addressed. Meanwhile, rationally orienting nanostructured TiO2 in chemical reactors for CO2 conversion and its prospects are highlighted for further development.
    Solar Energy Materials and Solar Cells 10/2012; 105:53-68. DOI:10.1016/j.solmat.2012.05.037 · 5.34 Impact Factor
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    • "While the demand for renewable sources of energy is increasing day by day, dye-sensitised solar cells (DSSCs) are gaining more and more attention as a promising alternative to the traditional silicon devices [10] [30]. In a DSSC, a layer of an organic or metal-based dye is bound to the surface of a nanoporous TiO 2 film (usually exposing the (101) face of the anatase polymorph), forming a chromophore/semiconductor interface which has been extensively investigated (see Ref. [2] [5] [17] [18] [31] [35] [41] [43] and Ref. [24] for a recent review). The carboxyl group –COOH constitutes the binding anchor of the most widely used Ru-based dyes. "
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    ABSTRACT: We have studied by density functional theory the amorphous Al2O3 (a-Al2O3)/TiO2 anatase (101) interface. The a-Al2O3 sample was generated by following a “melt and quench” technique, in which the corundum phase of Al2O3 was first melted at the temperature of 5000 K and then gradually cooled to 0 K. Once placed on TiO2 anatase, the overlayer has been employed for the adsorption of formic acid (HCOOH). Compared to the bare anatase (101), the adsorption of HCCOH is enormously stabilized in the presence of the coating, regardless of its thickness. Additional calculations confirm the trend also when the benchmark N3 dye, binding through two carboxyl groups (−COOH), is used. These results help to understand the improvement in dye-sensitized solar cell efficiencies after the a-Al2O3 coating of the TiO2 electrode.
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