To characterize lattice defects in a semiconductor, several techniques were used during the second half of the last century. Between these methods, we cite the thermally stimulatedcurrent (TSC) (Leonard & Grossweiner, 1958; Bube, I960), the admittance spectroscopy (Losee, 1974), the increase or decay curves of photoconductivity (Rose, 1951; Devore, 1959), the optically stimulated conductivity (Lambe, […]

Boussairi Bouzazi1, Hidetoshi Suzuki2, Nobuaki Kijima1, Yoshio Ohshita1 and Masafumi Yamaguchi1 1Toyota Technological Institute 2Myazaki University Japan 1. Introduction With only 3 % of N and 9 % of In, InGaAsN with a band gap of 1.04 eV was obtained and could be lattice matched to GaAs and Ge. This dilute nitride semiconductor has been […]

Figure 2 shows the PA spectra of the nanostructured TiO2 electrodes adsorbed with combined CdS/ CdSe QDs for different adsorption times, together with that adsorbed with CdS QDs only. The pre-adsorption times for CdS QDs were fixed at 40 min (average diameter: ~ 4.2 nm). The spectra were normalized to the photon energy of 4.0 […]

Photocurrent measurements were performed in a sandwich structure cell (i. e., in the two- electrode configuration) with Cu2S film on brass as the counter electrode (termed the Cu2S counterelectrode). The applied electrolyte was polysulfide solution (1 M Na2S + 1 M S). It is well known that the electrocatalytic activity of Pt with a polysulfide […]

The optical absorption properties of nanostructured TiO2 electrodes adsorbed with combined CdS/CdSe QDs were investigated using PA spectroscopy. The scattering effects in the optical absorption of nanostructured TiO2 electrodes adsorbed with combined CdS/ CdSe QDs can be minimized by employing the PA method. Figure 1 shows the schematic diagram of a photoacoustic spectrometer. Typical gas-microphone […]

The method for the preparation of nanostructured TiO2 electrodes has been reported in a previous paper (Shen & Toyoda, 2003). A TiO2 paste was prepared by mixing 15 nm TiO2 nanocrystalline particles (Super Titanai, Showa Denko; anatase type structure) and polyethylene glycol (molecular weight: 500,000) in pure water. The resultant paste was then deposited onto […]

Experimental sections are divided into three sections, 1) sample preparations on TiO2 electrodes and CdS/CdSe quantum dots, 2) optical absorption measurements by photoacoustic technique, and 3) photoelectrochemical current (incident photon to current conversion efficiency) and photovoltaic measurements.

Taro Toyoda and Qing Shen The University of Electro-Communications Japan 1. Introduction There is a great deal of interest in the technological applications of titanium dioxide (TiO2) to dye-sensitized solar cells (DSCs) made from nanostructured TiO2 electrodes because of their high photovoltaic conversion efficiency, which exceeds 10% (Chiba et al., 2006). Since the initial pioneering […]