am7b00208_si_001.pdf (1.67 MB)
Degradation of Hole Transport Materials via Exciton-Driven Cyclization
journal contribution
posted on 2017-03-28, 00:00 authored by Bruce
M. Bell, Michael B. Clark, David D. Devore, Timothy S. De Vries, Robert D. Froese, Kaitlyn C. Gray, David H. K. Jackson, T. F. Kuech, Hong-Yeop Na, Kenneth L. Kearns, Kyung-Joo Lee, Sukrit Mukhopadhyay, Aaron A. Rachford, Liam P. Spencer, W. H. Hunter WoodwardOrganic light-emitting
diode (OLED) displays have been an active and intense area of research
for well over a decade and have now reached commercial success for
displays from cell phones to large format televisions. A more thorough
understanding of the many different potential degradation modes which
cause OLED device failure will be necessary to develop the next generation
of OLED materials, improve device lifetime, and to ultimately improve
the cost vs performance ratio. Each of the different organic layers
in an OLED device can be susceptible to unique decomposition pathways,
however stability toward excitons is critical for emissive layer (EML)
materials as well as any layer near the recombination zone. This study
will specifically focus on degradation modes within the hole transport
layer (HTL) with the goal being to identify the general decomposition
paths occurring in an operating device and use this information to
design new derivatives which can block these pathways. Through post-mortem
analyses of several aged OLED devices, an apparently common intramolecular
cyclization pathway has been identified that was not previously reported
for arylamine-containing HTL materials and that operates parallel
to but faster than the previously described fragmentation pathways.