利用正向與反向光電子能譜分析儀分析OLEDs中介面能階匹配及 利用石墨烯實現全濕式製程穿透OLEDs元件之研究

Abstract

Direct photoemission spectroscopy (PES) has been widely used to investigate the interfaces and surfaces of organic materials, including ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). However, inverse photoemission spectroscopy (IPES) is more difficult to obtain and not widely used as direct PES due to its extremely low yield of inverse photoemission process. The IPES is set up in this work. With combination of UPS and IPES in the identical equipment, more details of the electrical properties in the organic materials can be investigated. In this dissertation, the mechanism of charge generation and transport in tandem organic light emitting diodes (OLEDs) and AC-driven OLEDs are explored via UPS and IPES simultaneously. Moreover, the application and physical mechanisms of 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) in organic devices are also investigated with XPS, UPS and IPES, including the charge generation mechanism of tandem-OLEDs based on n-type doped ETL/HAT-CN structure and the mechanism of improved stability of OLEDs with HAT-CN as hole injection layers. On the other hand, graphene thin films have a strong potential to be transparent electrodes in organic electronic devices with excellent conductivity and highly transparent properties. In this dissertation, n-type doped graphene with a new polymer-free transfer method is achieved. With n-doped multilayer graphene as top cathodes, all-solution-processed transparent OLEDs could be fabricated without any vacuum process.