학술논문
Horizontal Orientation of Disk-like Hole Transport Molecules and Their Application for Organic Light-Emitting Diodes Requiring a Lower Driving Voltage
Document Type
Article
Author
Source
The Journal of Physical Chemistry - Part C; April 2012, Vol. 116 Issue: 15 p8699-8706, 8p
Subject
Language
ISSN
19327447; 19327455
Abstract
Novel starburst type amorphous materials N1,N1,N4,N1-tetra(biphenyl-4-yl)benzene-1,4-diamine, N1,N1,N1,N1-tetrakis(4-(thiophen-2-yl)phenyl)benzene-1,4-diamine, and N1,N1,N1,N1-tetrakis(4-(benzo[b]thiophen-2-yl)phenyl)benzene-1,4-diamine are synthesized and applied as hole injection layers (HILs) in organic light-emitting diodes (OLEDs). OLEDs containing these materials as a HIL demonstrated a significant reduction in the required driving voltage. We found that these molecules form a horizontally oriented amorphous thin film upon vacuum deposition. We observed a close correlation between the reduction of driving voltage in OLEDs and the orientation parameter of the organic thin films. We identified that the enhanced horizontal molecular orientation results in the lower driving voltage because of a decrease in the hole injection barrier at the anode/HIL interface.