Hole mobilities of thermally polymerized triaryldiamine derivatives and their application as hole-transport materials in organic light-emitting diodes (OLEDs)

Abstract

This paper describes the synthesis of three triaryldiamine derivatives presenting two thermally polymerizable trifluorovinyl ether groups that can be polymerized through thermal curing to form perfluorocyclobutyl (PFCB) polymers. These PFCB polymers, studied using time-of-flight techniques for the first time, exhibited remarkable non-dispersive hole-transport properties, with values of μ h of ca. 10 −4 cm 2 V −1 s −1. When we employed these thermally polymerized polymers as hole-transport layers (HTLs) in electroluminescence devices containing tris(8-hydroxyquinolate) aluminum (Alq 3) as the emission layer, we obtained high current densities (ca. 3400 mA cm −2), impressive brightnesses (5 × 10 4 cd m −2), and high external quantum efficiencies (EQEs = 1.43%). These devices exhibited the same turn-on voltage, but higher EQEs, relative to those incorporating the vacuum-processed model compound N, N′-di(1-naphthyl)- N, N′-diphenylbenzidine (α-NPD) (EQE = 1.37%) as the HTL under the same device structure.