Electron transport with mobility above 10^–3 cm²/Vs in amorphous film of co‐planar bipyridyl‐substituted oxadiazole

Abstract

We demonstrate that a bipyridyl substituted oxadiazole (Bpy‐OXD) shows high electron mobility that reached above 10–3 cm2/Vs. We believe that the high mobility results from both the hybrid molecular structure of the two electron‐accepting units: bipyridyl and oxadiazole, and the planar molecular structure based on its lack of sterically hindered bulky substituent. The computational analysis elucidates that the amorphous nature of Bpy‐OXD in thin‐film state probably results from the polymorphic effect in isolated state and the volume effect in solid state. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Enhanced electroluminescence and reduced efficiency roll-off in electrophosphorescent devices using a very high electron mobility material as emitter host and electron transporter

“…Device C using Bphen as the HB layer shows better EL performance at a lower current density compared with Device B using BCP indicating that it has a higher electron transport ability at a lower current density. We know that the high electron mobility of Bpy-OXD is caused by its strong electronic interactions between adjacent molecules and its co-planar molecular structure [13] with a large π -electron system without any sterically hindered constituents. By comparing the molecule structure of BCP and Bphen (see figure 2), we can find that the difference is that BCP has two sterically hindered methyl moieties, which explains the difference in the electron mobility of Bphen [14] (5 × 10 −4 cm 2 V −1 s −1 ) and BCP [15] (6×10 −7 cm 2 V −1 s −1 ) for three orders of magnitude.…”

Bi- or ter-pyridine tris-substituted benzenes as electron-transporting materials for organic light-emitting devices

“…A 100-nm-thick fullerene C 60 layer was used as a charge-generation layer for optical excitation. [27] Computational chemistry was conducted with commercial software (Wavefunction Spartan 06W) on a personal computer with a dual-core processer. Density function theory (DFT) was used to determine conformations, with a B3LYP hybrid functional and a 6-311G* basis set for determining optimized geometries and estimating activation energies for conformation change.…”

P‐226: New Tris Bipyridyl Derivative as Hole‐Blocking and Electron‐Transporting Materials for Organic Light‐Emitting Devices

“…[1] Moreover, one of the materials showed extremely high electron drift mobility among amorphous organic electron-transporting materials; its mobility reached above 10-3 cm2/Vs. [2] On the other hand, we have also reported lately that bipyridyl substituted triazoles are also useful as electron-transporting materials for reducing operation voltages and power consumptions. [3] These results probably indicate that molecular level hybridization of bipyridyl to conventionally well-known electron-transporting molecular skeletons will be a valuable way to create new electrontransporting material with high performance.…”