Electrochemistry of Semiconductors

A critical assessment of the Mott-Schottky analysis for the characterisation of passive film-electrolyte junctions

“…In particular, it can be observed that, as start ing point, W(0) = 0, but dW/dψ gives an undetermined form (0/0) numerically unmanageable. According to this we can assume, near ψ = 0 W = Kψ (it respects the boundary conditions) and evaluate dW/dψ from the Taylor approximation of the functions Н, ρ, and F near 14) and expression (14) can be used to start the RungeKutta integration. The mathematical treatment, above reported, is valid for any kind of semiconductor and contains the simple Mott-Schottky model as a limit ing case of a non degenerated crystalline semiconduc tor with a single donor level fully ionized (N T = 0) at room temperature.…”

“…The most frequently employed method to derive the U fb value is by means of differential capacitance measurements and their rep resentation in the classical Mott-Schottky plots. This last theory, initially used for solid state junction, has been validated also for solid liquid junction trough the fifties [9,10] in several classical papers [11,12] and books [13][14][15].…”

Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

“…With respect to the metal/electrolyte interface in the case of SC/electrolyte interface the main differences stem out from the different electronic structure of the electrode. [16][17][18][19][20][21][22][23][24][25] In fact, differently than in a metal, owing to a much lower density of free carriers in the conduction band of semiconductor a much larger screening length in SC electrode is necessary to neutralize the excess of charge lying in the solution side.…”

“…Both techniques take advantage from the pioneering works of Garrett and Brattain in the mid 1950s and from the advent of Gerischer's theory and its systematic use for interpreting the kinetics of electron and ion transfer reactions (ETR and ITR) at the semiconductor/electrolyte interface. [15][16][17][18][19][20][21][22][23][24][25] We have to mention that both ITR and ETR are involved in determining the kinetics of growth and the breakdown processes of passive films. 1,2,[26][27][28][29][30][31][32][33] In many cases the combined use of both DA and PCS techniques is able to provide the information necessary to locate the characteristic energy level (flat band potential, U fb , conduction and valence band edge E C , E V ) of the passive film/electrolyte junction.…”

Dye-sensitized Solar Cells

“…It was later found that the photosensitivity can be extended to longer wavelengths by adding a dye to silver halide emulsions [2]. The interest in photoelectrochemistry of semiconductors led to the discovery of wet-type photoelectrochemical solar cells [3][4][5]. Grätzel has then extended the concept to OPEN ACCESS the dye sensitized solar cells (DSSC) by adsorption of dye molecules on the nanocrystalline TiO 2 electrodes.…”