Preparation and Luminescence Properties of Polymers Containing Dialkoxyacenes

Abstract

Derivatives of 2,3-(1,4-dialkoxyaceno)norbornadiene 1-4 underwent ring-opening metathesis polymerization (ROMP) reactions with a ruthenium carbene complex Cl 2 (PCy 3 ) 2 -RudCHPh to afford the corresponding polymers P1-P4 with narrow polydispersity. These materials exhibited luminescence both in solution and as films, whereas P3 and P4 were used successfully for the fabrication of light emitting diodes (LED). The device ITO/P4/Ca/ Al, made of a spin-coated layer of P3 or P4, displayed white light that can be turned on at 7 V with a maximum intensity of 427 cd/m 2 at 15 V. The white electroluminescence is composed of a blue emission band from the aromatic chromophore and a red component derived from solid aggregates. The performance of devices can be improved by insertion of an additional electron-transporting layer, i.e., 1,3,5-tris(2′-(1′-phenyl-1′-H-benzimidazole)benzene (TPBI). The device ITO/P4/TPBI/Mg:Ag displayed blue light with a turn-on voltage of 5 V and maximal intensity of 930 cd/m 2 at 15 V. The change of chromaticity can be ascribed to a shift of charge recombination sites in the bulk of P4 film. The phenomenon was verified by adjusting the thickness of TPBI layer, whereas a continuous variation in color was observed upon changing bias.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

“…The best EL performance was obtained from a blue-white emitting single-layer device using the sulfonated polymer 971 (Chart ), but the external EL efficiency was still miserably low (5.4 × 10 −4 %). The anthracene-susbtituted polynorbornenes 972a,b display blue-green solid-state PL (λ max = 450 and 470 nm, respectively), but single-layer LEDs produce white EL with an additional red emission band in the red assigned to aggregates . Blue-green emission was obtained from double-layer devices with an electron-transporting layer.…”

Polymers with dihydroxy/dialkoxybenzene moieties

“…Chow [19] also used the ROMP technique to polymerize some derivatives of 2,3-(1,4-dialkoxyaceno)norbornadiene employing a ruthenium carbene complex Cl 2 (PCy 3 ) 2 Ru ¼ CHPh as a catalyst to afford the corresponding polymers. These polymeric materials exhibited luminescence both in solution and in films, and were used successfully for the fabrication of light-emitting diodes (LED).…”

First Example of White Organic Electroluminescence Utilizing Perylene Ester Imides

“…This requires the doping or combination of several components . In literature, the problem of obtaining an efficient WOLEDs has been approached with different classes of materials like small organic molecules, specifically tailored polymers, blends of different luminescent polymers, and layered polymer structures, integration of the above materials with phosphorescent iridium complexes, or blending of emissive semiconducting polymers with organometallic emitters …”