Degradation Mechanism of Small Molecule-Based Organic Light-Emitting Devices
Hany Aziz,
1
Zoran D. Popovic,
2*
Nan-Xing Hu,
2
Ah-Mee Hor,
2
Gu Xu
1
Studies on the long-term degradation of organic light-emitting
devices (OLEDs) based on tris(8-hydroxyquinoline) aluminum (AlQ3), the most widely used electroluminescent molecule,
reveal that injection of holes in AlQ3 is the main cause of
device degradation. The transport of holes into AlQ3 caused
a decrease in its fluorescence quantum efficiency, thus showing that
cationic AlQ3 species are unstable and that their
degradation products are fluorescence quenchers. These findings explain
the success of different approaches to stabilizing OLEDs, such as
doping of the hole transport layer, introducing a buffer layer at the
hole-injecting contact, and using mixed emitting layers of hole and
electron transporting molecules.
1 Department of Materials Science and
Engineering, McMaster University, Hamilton, Ontario, Canada.
2 Xerox Research Centre of Canada, Mississauga,
Ontario, Canada.
*
To whom correspondence should be addressed.
