The Fabrication of K2CO3-doped NiO Anode Buffer layer and Its Applications in Organic Light-Emitting Diodes

摘要

OLED (Organic-Light Emitting Diode) is a semiconductor technology just like an LED (Light Emitting Diode) component made by inserting multiple sheets of organic thin film between two conductors Unlike liquid-crystal displays (LCDs) OLED screens can be made very thin have wide viewing angles and can be used on bending transparent displays In addition OLEDs have other advantages such as low-voltage operation fast response and low cost As a result research on the OLED’s performance improvement and operating mechanism are thoroughly discussed in recent years In this study we use thermal evaporation method to deposit metal oxide films as inorganic buffer layer in OLEDs devices and investigate how the K2CO3-doped NiO buffer layers improve device performance We also use Admittance Spectroscopy technique for the investigation of reliability evaluation for OLED display First we used various concentrations and thickness of alkali metal-doped metal oxide anode buffer layers on the ITO substrates The anode substrates were then subjected to UV-O3 surface treatment We studied the effect and mechanism on the improved hole injection properties of OLEDs with different measurement methods X-ray Photoelectron Spectroscopy and Ultraviolet Photoelectron Spectrometer were used to measure molecules’ binding energy and work function Contact angle measurement was used to measure surface energy and polarity Atomic Force Microscope was applied to measure the surface roughness Admittance Spectroscopy was utilized to measure the capacitance and conductance which can be used to obtain the sheet resistance With above measurement methods adding with improved turn on voltage luminance and current efficiency results we can conclude that alkali metal-doped metal oxide anode buffer layers insertion between ITO and hole transporting layer may significantly improve performance of OLED devices Next we applied the optimal parameters of anode buffer layers on different emission layer properties The objective of this work is to examine different emitting attribute OLED devices using metal oxide hole injection layer and to provide optimum design for each case We studied different affect and mechanism on emission layers as different emission mechanism could produce various phenomenon Finally the investigation of charge transfer mechanism of OLEDs is crucial to determine performance and reliability To determine these characteristics two different OLED devices were elucidated to test on cell level and characterized by luminance-current-voltage (L-I-V) capacitance-voltage (C-V) and Secondary-ion Mass Spectrometry (SIMS) measurement Additionally the purpose of these measurements was also to perform accelerated test which can be utilized to predict devices’ long term performance and perform observation on the migration phenomenon of ions in organic materials

獎項日期	2018 8月 7
原文	English
監督員	Sheng-Yuan Chu (Supervisor)