3 research outputs found
π‑Conjugated Polymers Composed of BODIPY or Aza-BODIPY Derivatives Exhibiting High Electron Mobility and Low Threshold Voltage in Electron-Only Devices
We
present efficient electron-transport materials based of polymers.
Ď€-Conjugated copolymers composed of boron dipyrromethene (BODIPY)
or Aza-BODIPY were synthesized via the efficient Suzuki–Miyaura
cross-coupling reaction of (2,5-bisÂ(2-(2-(2-(pyridin-2-yloxy)Âethoxy)Âethoxy)Âethoxy)-1,4-phenylene)Âdiboronic
acid with each of the diiodo-substituted BODIPY and Aza-BODIPY. Synthesized
polymers exhibited high solubility even in polar solvents such as
acetic acid. Their electronic and optical properties were studied
by cyclic voltammetry, UV–vis absorption, and photoluminescence
spectroscopies. The absorption and photoluminescence spectra of the
obtained polymers were red-shifted in comparison with the corresponding
monomers due to the increase in the HOMO level by the formation of
donor–acceptor interactions and the expansion of main-chain
conjugations, explained by their cyclic voltammograms and theoretical
calculations of the model compounds using the density-functional theory
method. Finally, the electron mobilities of the polymers were determined
from the space-charge-limited current with electron-only device structure
of ITO/Ca/polymer/BCP/LiF/Al. As a result, owing to their high electron
acceptability and strong stacking interaction among the BODIPY or
Aza-BODIPY units, it was found that the mobilities for the polymers
((1.5–3.6) × 10<sup>–4</sup> [cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>]) were much higher than the
value of Alq<sub>3</sub> (5.8 × 10<sup>–5</sup> [cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>]), and their
threshold voltages (5–7 V) were much smaller than that of the
Alq<sub>3</sub> device (12 V)
Cyclo‑<i>meta</i>‑phenylene Revisited: Nickel-Mediated Synthesis, Molecular Structures, and Device Applications
From a one-pot nickel-mediated Yamamoto-type
coupling reaction
of <i>m</i>-dibromobenzene, five congeners of [<i>n</i>]Âcyclo-<i>meta</i>-phenylenes were synthesized and fully
characterized. The [<i>n</i>]Âcyclo-<i>meta</i>-phenylenes possessed a commonly shared arylene unit and intermolecular
contacts but varied in packing structures in the crystalline solid
state. Columnar assembly of larger congeners yielded nanoporous crystals
with carbonaceous walls to capture minor protic or aliphatic solvent
molecules. The concise and scalable synthesis allowed exploration
of the macrocyclic hydrocarbons as bipolar charge carrier transport
materials in organic light-emitting diode devices
Modular Synthesis of Aromatic Hydrocarbon Macrocycles for Simplified, Single-Layer Organic Light-Emitting Devices
A method
for the modular synthesis of aromatic hydrocarbon macrocycles
has been developed for base materials in single-layer organic light-emitting
devices. The method with Ir-catalyzed direct C–H borylation
and Suzuki–Miyaura coupling was concise and scalable, which
allowed for a gram-scale preparation of aromatic hydrocarbon macrocycles
that have bulky substituents at the periphery. The new arylated hydrocarbon
macrocycles enabled a quantitative electro-optical conversion in organic
light-emitting devices with a phosphorescent emitter, which is, notably,
in a single-layer architecture consisting of two regions of doped
and undoped materials. The highest external quantum efficiencies reached
24.8%, surpassing those of previous hydrocarbon base materials