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Mott-Schottky Analysis of Nanoporous Semiconductor Electrodes in Dielectric State Deposited on SnO[sub 2](F) Conducting Substrates

2003; Institute of Physics; Volume: 150; Issue: 6 Linguagem: Inglês

10.1149/1.1568741

1945-7111

Francisco Fabregat‐Santiago, Germà Garcia‐Belmonte, Juan Bisquert, Peter Bogdanoff, Arie Zaban,

Copper-based nanomaterials and applications

This paper analyzes the dark capacitance of nanostructured electrodes in the dielectric state, with particular emphasis on electrodes deposited over a transparent conducting substrate of It is shown that at those potentials where the nanostructure is in the dielectric state, the capacitance is controlled by the contact The partial or total covering of the substrate by a dielectric medium causes a modification of the Mott-Schottky plot of the bare substrate. We provide a mapping of the various Mott-Schottky curves that will appear depending on the film characteristics. If the dielectric nanoparticles completely block part of the substrate surface, the slope of the Mott-Schottky plot increases (with the same apparent flatband potential) as an effect of area reduction. The covering of a significant fraction of the surface by a thin dielectric layer shifts the apparent flatband negatively. Measurements on several nanostructured electrodes show that the capacitance contribution of the semiconductor network in the dielectric state is very low, indicating that the field lines penetrate little into the network, not much further than the first particle. The different surface covering observed for rutile-anatase and pure anatase colloids is explained by lattice matching rules with the substrate. By comparing different electrodes, the Helmholtz capacitance at the interface was calculated and the apparent flatband potential was corrected for the effect of band unpinning. © 2003 The Electrochemical Society. All rights reserved.