采用吸收光谱, 荧光光谱和瞬态光伏技术研究了卟啉/TiO体系的吸收光特性, 荧光特性和光伏特性, 并研究了卟啉和TiO之间的界面相互作用.研究结果表明, 卟啉环在与钬原子结合前后与TiO之间的作用不同, TiO的粒径也影响界面的相互作用。卟啉与粒径为10mm的TiO的作用后, 能级发生了简并, 同时带隙发生了红移。卟啉与粒径为56mm的TiO相互作用后只有特征吸收峰发生红移, 带隙和峰的数量几乎未发生变化。这说明在粒径为10mm的TiO与卟啉的大π键之间出现了离域的相互作用, 这也被荧光光谱和瞬态光伏曲线所证实。

The degeneration of energy level ofα, β, γ, δ-tetrahydroxylphenylporphyrin(THPP)and red shift of the photovoltage peaks of THPP are observed as the size of nano-TiO2 decreasing using surface photovoltage(SPV)technique, while that ofα, β, γ, δ-tetraphenylporphyrin(TPP)have little change. The reason for that is the existence of hydroxyls of THPP, which interact with the surface of nano-TiO2. This difference was also demonstrated by IR spectrum.

The electric field induced dipole model which is useful for interpreting the mechanism of photogenerated charge transfer in nano-TiO2 has been introduced using photovoltage electric field scanning technique. Based on above model, we suppose that diffusion mechanism controls the photogenerated charge transfer in nano-TiO2. Also, we have studied the behavior of charge transfer in nano-TiO2 under external electric field and found that the photogenerated charge transfer is controlled by different transfer mechanisms under different applied external electric field.

CdS semiconductor nano-films were grown on ITO glass substrates by means of hemical bath deposition(CBD), with Cd(NO3)2 as Cd ion and(NH2)2CS as S ion sources. The concentration of Cd ions,deposition temperature, deposition time and posttreatment temperature have an impact on the formation of CdS nano-films. UV-vis absorption spectrum and atomic force microscope(AFM)images indicated that the change of concentration and post-treatment temperature may adjust the band-gap of CdS to obtain stable, homogeneous and compact films. Formation mechanism of the crystal nucleus and CdS film was also discussed. Active sites on the surface of ITO are critical to the formation of the crystal nucleus and a uniform and compact CdS nano-film. The active site and crystal nucleus are formed due to the comprehensive effect of electricity, thermodynamics and chemistry.

This paper presents a novel one-step method to synthesize nano/micron-sized ZnO pheres assembled from the aggregation of nano-particles. It was observed that ZnO spheres with controllable diameter were obtained when various volume ratios of triethanolamine(TEA)to H2O were used. Increasing the volume ratio of TEA to H2O could favor the formation of densely packed ZnO spheres. The UV-vis absorption spectra show that the absorption peak red-shifts with the increasing average diameter of the spheres. On the basis of the experimental results, we proposed a possible mechanism to elucidate the formation of ZnO spheres.