Organic-Inorganic Interface Energy Level Alignment Based On Interface Modification

With the active-matrix organic light-emitting diodes ?AMOLEDs? used in the smart phone screen by Samsung, the world's major display manufacturers ?including LG, Qi Jing. TMD. AUO and so on? flock to this field due to the high degree of color revivification, simple manufacturing process, flexible, large area production and other characteristics. The OLED generally includes an anode, a hole transport layer, a light emitting layer, an electron transport layer and a cathode. The light emitting layer is generally consisted of a doped organic material. And in order to improve efficiency and stability of OLED device, the hole and electron transporting layer usually use an inorganic metal oxide. Thus, the electronic structure of organic-inorganic interfaces and properties of charge transport at the interfaces are particularly important.Organic-inorganic interface electronic structure and energy level alignment depends not only on the electronic structure of the material itself, but also the molecular orientation at the interface, the substrate work function and disorder induced defect states are also far-reaching. In this thesis, the energy level alignment at the organic-inorganic interface was studied.Firstly, we studied the influence of different annealing temperature and oxygen atmosphere conditions on transition metal oxide NiO_x as a hole transport layer material. The electronic structure and topography of NiO_x film with different treatment conditions was investigated by photoelectron spectroscopy ?XPS and UPS? and atomic force microscopy ?AFM?.Additionally, a wide range of work function ?2.5 eV-6.7 eV? of the NiO_x substrate was realized by introducing modified layers. And the interaction between the modified layer and the NiO_x substrate layer was described, as well as variation of the electronic structure of posttranslational modification.After the deposition of organic host material on these modified substrates, the electronic structures of these organic-inorganic interfaces were investigated. The charge transport mechanism at the interfaces was systematically analyzed by photoelectron spectroscopy and other analytical tools.Finally, after the introduction of these modified NiO_x structures into OLED devices, we can easily see the greatly decrease of the charge transport barrier and the improved device efficiency.In addition, we continue to study the effects of molecular orientation at organic-inorganic interface and its influence to energy level alignment. After depositing organic material, F₁₆CuPc, on the typical inorganic metal material Au and inorganic transition metal sulfide MoS₂ substrate, we obtain the relationship between the molecular orientation and structure of the energy level by photoelectron spectroscopy.