The photoelectron property is directly related to the light-energy conversion efficiency of solar cells. In this paper, the photoelectron dynamic of semiconductor was analyzed. The diffusion of electrons has influence on the dielectric function of the solar cell material. And the amplitude variance of the imaginary and real part of the dielectric function is in direct proportion to the dynamic process of free and shallow-trapped electrons. Based on the untouched detection technique, the method is present to detect the amplitude change of the microwave signal which is passing through the material whose dielectric function changes after exposure. A 35 GHz oscillator was used as a microwave source. The absorption and dispersion microwave signals, which contain the dynamic information of free and shallow-trapped electron signal, are split respectively with phase-sensitive instrument. The photoelectron character of n-type Si(100) thin film was investigated by the novel equipment, and the lifetime of different kinds of electrons with the resolution of 1 ns was obtained. The equipment can be directly used in the study of the optoelectronic conversion mechanism of solar cells.
LI Xiaowei SUN Shuxu LAI Weidong ZHANG Rongxiang DAI Xiuhong JIANG Xiaoli
Dye sensitization is a fundamental function for solar cell and silver halide (AgX) microcrystal to increase the optoelectronic conversion efficiency. In this paper, the spectral properties and self-assembled structure of three types of cyanine dyes, adsorbed both on (100) surface of 0.4 μm AgBr cubic crystal and (111) surface of 1.8 μm AgBr tabular crystal, were studied with combination of spectroscopy and atomic force microscopy (AFM) technique. Rectangular aggregation structure is formed on the crystal faces of (100) and (111) for both anionic and cationic dyes, while herringbone-stacking structure is formed by anionic-cationic dye, and a J-band spectrum is correspondingly detected. The photoelectron property of dye-sensitized samples was also investigated with microwave absorption and dielectric spectrum detection technology. After excited by a 355 nm fast-pulse laser, the photoelectron decay process of anionic-cationic dye sensitized sample is the fastest. This indicates that the affection of anionic-cationic dye aggregates to the photoelectron decay is the biggest, and the sensitization is more efficient.
JIANG Xiaoli LI Xiaowei LAI Weidong MENG Tao FENG Xiaomin ZHANG Jixian
