%0 Journal Article
%T Photosensitization of Colloidal SnO2 Semiconductor Nanoparticles with Xanthene Dyes
%A N. Nagarajan
%A G. Paramaguru
%A G. Vanitha
%A R. Renganathan
%J Journal of Chemistry
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/585920
%X The photochemical behavior of xanthene dyes (fluorescein, erythrosine, and eosin) with colloidal SnO2 nanoparticles was probed by UV-visible, steady state, and time resolved fluorescence measurements. The prepared SnO2 nanoparticles were characterized by using UV-visible and powder XRD measurements. The xanthene dyes were adsorbed on the surface of colloidal SnO2 nanoparticles through electrostatic interaction. Apparent association constant ( ) was calculated from the relevant fluorescence data. The larger value of apparent association constant indicates a strong association between xanthene dyes and SnO2 nanoparticles. The fluorescence quenching is mainly attributed to electron transfer from the excited state xanthenes to the conduction band of colloidal SnO2. The electron transfer mechanism was explained based on the Rehm-Weller equation as well as the energy level diagram. 1. Introduction The photosensitization of electron transfer across the semiconductor solution interface plays a vital role in light energy conversion in photoelectrochemical cells, wastewater treatment, nanoelectric devices, silver halide photography, and electrophotography. Effort in this area has concentrated on improving the visible light response of wide-band semiconductors such as SnO2, ZnO, and TiO2. Sensitization is achieved by adsorption of dye molecules at the semiconductor surface which, upon excitation, inject an electron into its conduction band [1, 2]. The first successful experiment of this type was described by Putseiko and Terenin [3] who found that the Dember effect of ZnO powder in visible light was sensitized by xanthene and cyanine dyes. The investigation and development of the dye-semiconductor systems are essential for various fields of applications. Recently Ferrere et al. and Tian et al. used perylene-SnO2 systems for dye sensitized solar cells [4¨C6]. The SnO2 is a stable n-type semiconductor with a wide-band gap ( £¿eV) being used for various applications, including solid-state gas sensor, photovoltaic devices, dye-based solar cells, transparent conductive films for display and solar cells, catalysis, and anode materials of secondary lithium ion battery [7¨C9]. Xanthenes belong to the most widely used organic dyes, serving as luminophores [10], molecular probes, bioconjugates, stains, and biologically active substances [11, 12]. These dyes are utilized for photosensitization of redox processes [13, 14] in energy transfer and light sensitization studies [15]. They are also used in light-harvesting dendrimers [16], in biochemistry and medicine as reactants for
%U http://www.hindawi.com/journals/jchem/2013/585920/