酞菁铜/金属薄膜界面电位与光二次谐波特性分析

采用Kalvin探针和光二次谐波 (SecondHarmonicGeneration ,SHG)方法研究了铜酞菁衍生物 (Coppertetra tert butylPhthalocyanine ,CuttbPc )LB(Langmuir Blodgentt)膜与金属 (Al、Au)界面的空间电荷现象与非线性光学效应 .检测到空间电荷感应电场 (SpaceChargeInducedElectricField ,SCIEF)形成的表面电位与金属功函数有关 ,并随膜厚变化趋于饱和值 .尽管酞菁分子为中心对称体系 ,但仍有SHG效应 ,并观察到CuttbPc/Al样品在 12 6 0nm附近有异常增强的SH信号 ,而CuttbPc/Au样品未见该峰 .根据样品结构的物理模型 ,运用电磁场理论分析了界面电介质的非线性极化特性和光学效应产生机制 ,初步认为CuttbPc/Al的SH增强峰源于SCIEF形成的较强表面电位 ,说明SH信号的产生与界面静电现象有密切关系 .

Analysis of the Surface Potentials and the Characters of Optical Second Harmonic Generation at the CuttbPc LB Film/Metal Interface

Using the Kelvin probe and the optical second harmonic generation (SHG) measurement, the space charged phenomenon and the non-linear optical effects at the interfaces of the copper tetra-tert-butyl phthalocyanine (CuttbPc) Langmuir-Blodgett (LB) film deposited on a metal (Al or Au) coated glass slide substrate were investigated. The surface potentials decrease as the film thickness increases and eventually approaches a saturated value. The SHG has been detected although there is a centro-symmetric system in the CuttbPc molecular, and a very strong SH signal can be investigated at 1260 nm band for CuttbPc/Al samples. According to a proposed physical model for CuttbPc LB film/metal, the nonlinear mechanism were analyzed by using electromagnetic wave theory. It is considered that the enhanced SH peak of CuttbPc/Al is attributed to the strong surface potential aroused by SCIEF at the interface, and shows that the production of SH signal is correlated closely with the electrostatic phenomena at the interface.