title: Degradation of Hole Transport Materials via Exciton-Driven Cyclization.
abstract: Organic 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.
authors.affiliation: Core Research and Development, The Dow Chemical Company , Midland, Michigan 48674, United States.
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Bell
authors.affiliation: Core Research and Development, The Dow Chemical Company , Collegeville, Pennsylvania 19426, United States.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Clark
authors.affiliation: Core Research and Development, The Dow Chemical Company , Midland, Michigan 48674, United States.
authors.forename: David D
authors.initials: DD
authors.lastname: Devore
authors.affiliation: Core Research and Development, The Dow Chemical Company , Midland, Michigan 48674, United States.
authors.forename: Timothy S
authors.identifier: http://orcid.org/0000-0003-2403-7265
authors.initials: TS
authors.lastname: De Vries
authors.affiliation: Core Research and Development, The Dow Chemical Company , Midland, Michigan 48674, United States.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Froese
authors.affiliation: Dow AgroSciences , Indianapolis, Indiana 46268, United States.
authors.forename: Kaitlyn C
authors.initials: KC
authors.lastname: Gray
authors.affiliation: Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: David H K
authors.initials: DHK
authors.lastname: Jackson
authors.affiliation: Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: T F
authors.initials: TF
authors.lastname: Kuech
authors.affiliation: Electronic Materials Research and Development, The Dow Chemical Company , Hwasung 445-170, South Korea.
authors.forename: Hong-Yeop
authors.initials: HY
authors.lastname: Na
authors.affiliation: Core Research and Development, The Dow Chemical Company , Midland, Michigan 48674, United States.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Kearns
authors.affiliation: Electronic Materials Research and Development, The Dow Chemical Company , Hwasung 445-170, South Korea.
authors.forename: Kyung-Joo
authors.initials: KJ
authors.lastname: Lee
authors.affiliation: Core Research and Development, The Dow Chemical Company , Midland, Michigan 48674, United States.
authors.forename: Sukrit
authors.initials: S
authors.lastname: Mukhopadhyay
authors.affiliation: Electronic Materials Research and Development, The Dow Chemical Company , Marlborough, Massachusetts 01752, United States.
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Rachford
authors.affiliation: Core Research and Development, The Dow Chemical Company , Freeport, Texas 77541, United States.
authors.forename: Liam P
authors.initials: LP
authors.lastname: Spencer
authors.affiliation: Core Research and Development, The Dow Chemical Company , Midland, Michigan 48674, United States.
authors.forename: W H Hunter
authors.initials: WHH
authors.lastname: Woodward
keywords: characterization tools; charge transport; organic electronics; organic light-emitting diodes; photochemistry