The Synthesis And Optoelectronic Properties Of Oxadiazole-Based Polymers

Abstract

New oxadiazole-based polymeric materials have been synthesized either as side chain copolymers with polymethacrylate or as main chain copolymers carrying solubilizing elements such as hexafluoropropylidene or meta-linked aromatic spacer units. Many of these materials exhibit blue luminescence in the solid state. The materials have been evaluated by photoluminescence and cyclic voltammetry studies, and as the electron transporting layer in a two-layer electroluminescent device with poly(p-phenylenevinylene) (PPV) as the emissive layer. The major conclusion is that these materials function by providing large heterojunction offsets at the Highest Occupied Molecular Orbital (HOMO) which block the passage of holes through the device.

Oxadiazole Metal Complex for Organic Light-Emitting Diodes

“…Two approaches have been adopted to modify oxadiazoles to improve the charge-transporting properties and minimize the problems of crystallization. One approach was to design branched molecules with multiple oxadiazole units, such as radialene, [13] starburst structures, [14,15] and dendrimers. [15,16] These materials have high glass-transition temperatures and form stable glasses, which minimize the problems of crystallization.…”

Synthesis and optical properties of new conjugated polymers composed of 1,3,4-thiadiazole and 2,5-dialkoxybenzene rings

“…The band gap energies of these polymers estimated from the extrapolated absorption edges are 2.58 -2.68 eV following the order 3 a F 3 c A3 b A 3 d and are lower than those of the 1,3,4-oxadiazole-containing compounds and conjugated polymers (more than 3.0 eV). [12,28] This means that the maximum conjugation length of polymers 3 a -d increases according to 3 a a 3 c a 3 b a 3 ( Fig. 1) show resolved vibronic structure, and bluish green-emission maxima are observed around 458 and 484 nm when excited at 416 -422 nm.…”

Elektrolumineszierende konjugierte Polymere – Polymere erstrahlen in neuem Licht

“…Da der Ladungstransport in ECHB-Materialien hauptsächlich durch Elektronensprünge erfolgt, sollte eine Erhöhung der Zahl an (in diesem Fall) Oxadiazoleinheiten zu einer Verbesserung der ladungstransportierenden Eigenschaften führen. [135] Dieses Konzept wurde erweitert auf das Design von verzweigten, hochsymmetrischen Verbindungen wie 29, [136] Starburst-Dendrimeren [137,138] und kleinen Dendrimeren wie 30. [138,139] Diese Materialien haben hohe Glasübergangstemperaturen und bilden stabile Gläser, wodurch das Problem der Kristallisation verringert wird.…”

“…Zahlreiche polyaromatische Oxadiazole mit zufriedenstellender Leistung wurden beschrieben. [70,72,77,136,140] Ihre Löslichkeit läût sich wie bei 31 durch flexible Spacer erhöhen oder durch Verwendung von Copolymerstrukturen wie bei 32 (Schema 10). Das in Trifluoressigsäure lösliche, hochverzweigte Oxadiazolpolymer 33 lieû sich in einem Schritt herstellen.…”