有机半导体薄膜材料LUMO能级准确判定方法及关键影响因素研究

The lowest unoccupied molecular orbitals (LUMO) alignment is a critical factor for the interlayer charge transport efficiency in the organic semiconductor thin film materials. However, the materials synthesis and devices design are both inhibited due to the measurement error of LUMO position of inverse photoelectron spectroscopy (IPES) and electrochemical cyclic voltammetry (CV). The error of IPES is contributed by the poor resolution and the electron beam irradiation damage on the materials. Therefore, a field emission electron cathode with minimal energy broadening is employed to improve the resolution smaller than 400 meV. The position offset of the energy level caused by the irradiation damage will be quantified in the different type of materials through a bandpass photon detector. As a result, measurement error from IPES can be lowered to 100 meV in an organic thin film material. Moreover, The CV measurements will also be carried out with the materials used by the IPES, aims to optimize the quantitative relationship between CV and IPES.

有机半导体薄膜材料最低非占据分子轨道（LUMO能级）排列对层间界面处电荷输运效率具有重要影响。但是，通常测量能级位的反光电子能谱法和电化学方法判定精度较差，极大抑制了新材料合成与器件的开发。本项目拟采用场发射型电子源替代目前普遍在反光电子能谱仪中使用的热发射电子阴极，利用新型电子源能量展宽低的特点，优化反光电子能谱仪分辨率低于400 meV。通过窄带通光子探测器着重分析测量时电子入射对有机半导体材料辐照损伤现象，探索不同材料因损伤造成的LUMO能级位的偏离规律，将这种偏离定量化，并结合谱仪分辨率的改进，最终实现有机薄膜材料LUMO能级位的判定精度优于100 meV。同时使用电化学法完成相同材料LUMO能级的测定，将结果与能谱法做比较分析，修正两者间的定量关系式，向大多数只能进行电化学法测定能级的用户提供参考。