A Novel Hole-Confining Concept for Efficient Green Organic Light Emitting Diodes

by Harikrishna Mohan, Siddharth

Abstract (Summary)
Organic light emitting diode (OLED) technology has initiated a lot of interest in the display and solid state lighting market during the last decade. The advantages of OLED displays include high brightness and contrast, broad color gamut, wide viewing angle, low power consumption, light weight and flexibility. As a result, a stream of new OLED products has reached the market in the last five years. Though the field is rapidly growing, much time and effort must still be devoted on improving the OLED efficiency and lifetime. In this thesis, we demonstrate improved efficiency of green OLEDs by using a novel hole confining concept. In the first part, an explanation of the various fabrication steps of ITO/PEDOT/TPD/BCP/Alq3/BCP/LiF/Al green OLEDs is presented. The concept of hole confinement is then discussed and luminance improvement of green OLEDs implementing this idea is demonstrated. In the second part, luminance and efficiency improvement in green OLEDs implementing a co-evaporated layer of BCP and Alq in a ITO/KHIL/NPB/BCP:Alq/Alq/BCP/LiF/Al structure is shown. Device performance improvement using a co-evaporated hole blocking layer (HBL) and Alq layer, with a general hole confining structure, ITO/CFx/NPB/HBL:Alq/Alq/BCP/LiF/Al is proved with three hole blocking materials in the HBL:Alq layer. Finally, performance comparison of the different HBLs used in the HBL:Alq mixed layer is discussed, and suggestions for future work are offered.
Bibliographical Information:


School:University of Cincinnati

School Location:USA - Ohio

Source Type:Master's Thesis



Date of Publication:01/01/2008

© 2009 All Rights Reserved.