Kiminori Itoh

Determining height of a leaky Schottky barrier existing in the junction between SnO2 and a highly doped p-type amorphous SiC by using the pulsed laser-induced transient photopotential technique

The junction between SnO2 and a highly doped p‐type amorphous SiC [a‐SiC(p+)] is very important as a transparent contact to an a‐Si alloy based solar cell. An energy‐band diagram for this junction has been obtained here for the first time. A thin film of a‐SiC(p+) deposited onto a SnO2‐coated glass was immersed into a nonaqueous electrolyte solution and was irradiated with N2 laser pulses. The photopotential was monitored against a Ag reference electrode. The photopotential thus obtained showed that a leaky Schottky barrier exists at the SnO2/a‐SiC(p+) junction. A band diagram was estimated, using an asymptotic value of the photopotential together with a position of the Fermi level calculated on the basis of the dark conductivity data.

Conversion electron Mössbauer study of thin film iron oxide photoelectrodes

Abstract Thin films of iron oxide deposited onto transparent conducting glasses by a spray pyrolysis technique were characterized by conversion electron Mossbauer (CEM) spectrometry. The iron oxide films deposited onto SnO 2 -coated glass consisted of large particles of well-crystallized α-Fe 2 O 3 , the magnetic moments of which were suggested to be oriented parallel to the surface with decreasing thickness of the α-Fe 2 O 3 layers. The doublet observed in the CEM spectra of iron oxide films deposited onto In 2 O 3 - and ZnO-coated glasses can be attributed to supermagnetism due to microcrystals of α-Fe 2 O 3 or to the formation of spinel structures (InFeO 3 and ZnFe 2 O 4 ). The growth of thin iron oxide films was found to depend on the substrate material used.

Sensitized delayed fluorescence of rubrene. Large temperature dependence of triplet lifetime of rubrene

Abstract The temperature dependence of the lifetime of rubrene triplet (τ R ) in ethanol was measured by tile sensitized delayed fluorescence technique. τ R is 125 μs at room temperature and increases on lowering tile temperature. reaching an asymptotic value of ≈ 1 ms An important intramolecular quenching process is proposed.

A study on thin film Fe2O3 photoanodes by measuring laser‐induced photopotential

Laser‐induced fast transient photopotentials were measured at Fe2O3 film electrodes. A photopotential rise within 300 ns was interpreted in terms of charge separation processes in the film, considering the contributions from both the electron and the hole. The time course of the photopotential up to 10 μs was attributed to the electron–hole recombination process and the interfacial charge transfer.

A new aspect on the mechanism of dye sensitization. Donor concentration dependence of the photocurrent

Abstract The photocurrent of electrochemical spectral sensitization for xanthene dyes depends largely upon the donor concentration of SnO 2 substrates. Evidence for a fast deactivation process, which occurs at the electrode surfaces, was given on the basis of the results of supersensitization and fast photopotential transient measurements.

Area‐selective deposition of organic conducting polymers on semiconductors: Polypyrrole‐ZnO system

Area‐selective deposition of polypyrrole was successfully performed by three different procedures with electrochemical and photoelectrochemical techniques. These methods are important as tools for organic conducting pattern generation and functionalization of electrode surfaces.

Application of a pulsed laser-induced photopotential technique to the current doubling process on polycrystalline oxide semiconductor electrodes

Abstract The laser-induced photopotential was measured on n-ZnO and n-TiO 2 polycrystalline electrodes with and without a “current doubling reagent” HCOONa. The rise time of the photopotential was 5–10 ns. The origin of the photopotential, the kinetics and the mechanism of the current doubling process are discussed.

Temperature dependence of ECL efficiency of rubrene

Abstract It was found that the electrochemiluminescence (ECL) efficiency, Φ ECL of rubrene increased with lowering temperature, reaching ca. 3% at around 0°C in a DMF—benzene mixed solvent. Taking into account the dependence of Φ ECL on the solvent, as well as on the frequency of applied voltage, it is concluded that the observed temperature dependence of Φ ECL arises from a decrease in the rate of triplet quenching at lower temperatures.