【作者】 程晓曼；

【导师】 姚素薇；

【作者基本信息】 天津大学 ， 应用化学， 2007， 博士

【摘要】 近年来有机光电器件得到迅猛发展,有望取得重大突破,成为一个十分活跃的研究领域。然而在有机光电器件中不可避免的会涉及有机材料与金属电极相接触的界面问题,光电器件最终性能的发挥与器件的界面特性密切相关。本文针对有机光电器件中存在的共性问题,即有机材料与金属电极相接触的界面性质进行了理论和实验新方法的研究。主要工作内容有:1.建立了用于有机超薄膜/金属界面特性测量的光二次谐波理论。基于有机超薄膜/金属界面样品结构,构建了四层物理模型。由麦克斯韦方程组出发,根据强光与物质相互作用引起的非线性极化过程和相应的边界条件,首次推导出光在界面中传播的线性过程和非线性过程,给出了基频(ω)和倍频(2ω)条件下,前向波、后向波、反射波和透射波在不同偏振入射场合电场强度的表达式,不同偏振方向入射与输出光强之间的对应关系。为开展利用光二次谐波测量有机超薄膜/金属界面特性的实验奠定了理论基础。2.首次进行了利用光二次谐波法测量有机超薄膜/金属界面特性的实验。选用具有优异光电性能的酞菁铜衍生物(copper tetra- tert-butyl Phthalocyanine, CuttbPc)作为有机层,采用LB膜制膜技术,制备了有机超薄膜。搭建和调试了光二次谐波测量系统,观察到CuttbPc LB膜/金属(Al或Au)界面在1000～1300nm波段光二次谐波产生的现象,分析了其产生机制。测量并计算了非线性极化率χQ和χdc等参数,实验结果与理论计算得到较好的符合。这是一种突破传统研究手段,获得有机超薄膜/金属界面特性测量的新方法。3.利用传统电学测量方法——Kelvin探针法测量了CuttbPc LB膜/金属(Al或Au)样品界面电位,计算出空间电荷和电子态密度分布等参数,得到CuttbPc LB膜与金属(Al和Au)界面处表面电位随膜厚的变化等一系列对应关系,验证了光二次谐波法测量结果,揭示了光二次谐波信号与界面电位等电学参数的内在关系。4.首次将电场调制谱方法用于有机超薄膜/金属界面特性的测量。观察到CuPc膜/金属(Al)界面的基频(1f)和倍频(2f)电场调制吸收信号均与外加调制电场的强度成正比。由此得到可以通过改变外加直流偏置电压推算表面静电势值的新方法。更多还原

【Abstract】 During the recent years, organic photo-electronic devices have been developed dramatically and hopefully get great research achievements. However, it is unavoidable that the interfaces between organic material/metals are the questions should be met in organic photo-electronic devices. The performance of the devices is closely related to the characteristics of the interfaces.The study of this dissertation is aimed to the common questions of in organic photo-electronic devices, characterize of the interface between organic material/metals, a novel of theoretical studies and experimental methods were carried out. The main works of this thesis were the followings:1. The second harmonic generation (SHG) theory for the measurement of the characteristics of interface between organic material and metals was set up. Based on the sample structure of organic LB film/metals, a physical four-layers model was lay out. Started from Maxwell equations, the linear and nonlinear procedures of light transformations in the interface were also introduced. The corresponding relations between the light intensities of input and output were presented for the forward wave, backed wave, reflective wave and transmitted wave under different incident directions and withωand 2ωseparately. It offered a theoretical foundation for the measurement experiments of the interface characteristics between organic material and metals by SHG method.2. The experiments for measuring the interface characteristics of organic LB film/metals were carried out firstly by using SHG method.CuttbPc and its derivative materials with excellent opto-electronic features were selected for the preparation of organic ultrathin film by using Langmuir-Blodgett (LB) film technique. SHG phenomena was observed in the interfaces of CuttbPc LB film/metals (Al or Au) from the 1000～1300nm and its mechanisms were investigated. The nonlinear susceptibility ofχQ andχdcwere measured and calculated. The results were coincided between experiments and theory. Thus SHG can be used as a new method for the measurement of the interface characteristics between organic material and metals. 3. The surface potentials of the interfaces between organic LB film and metals (Al or Au) were measured by using Kelvin probe method. Corresponding relations of the surface potentials and film depths were tested and verified results of SHG measurements. It shows the inhesion relations between SHG signals and the electric parameters of interfaces, such as surface potential etc.4. The electroabsorbance (EA) spectrum method was used firstly, to measure the characteristics interface between the organic ultrathin film/metals. A new method that the calculate the surface electrostatic potentials can be get by changing the supplied direct-current (DC) bias voltages was presented.更多还原