Blue fluorescent conductive poly(9,10‐di(1‐naphthalenyl)‐2‐vinylanthracene) homopolymer and its highly soluble copolymers with styrene or 9‐vinylcarbazole

Abstract

A new blue fluorescent monomer, 9,10‐di(1‐naphthalenyl)‐2‐vinylanthracene, was designed and synthesized in good yield. Its homopolymer poly(9,10‐di(1‐naphthalenyl)‐2‐vinylanthracene) (P(ADN)) and soluble conductive vinyl copolymers poly[(9,10‐di(1‐naphthalenyl)‐2‐vinylanthracene)‐co‐styrene] (P(ADN‐co‐S)) and poly[(9,10‐di(1‐naphthalenyl)‐2‐vinylanthracene)‐co‐(9‐vinylcarbazole)] (P(ADN‐co‐VK)) were synthesized using free radical solution polymerization. All the polymers showed high glass transition mid‐point temperatures (203 to 237 °C) and good thermal stabilities. The photoluminescence emission of the copolymers was similar to that of P(ADN) (with two maxima at 423 and 442 nm). The lifetimes of P(ADN‐co‐S) (6.82 to 7.91 ns) were all slightly less than that of P(ADN) (8.40 ns). The lifetime of P(ADN‐co‐VK) increased from 7.8 to 8.8 ns with an increase in VK content. The fluorescence quantum yields of P(ADN‐co‐S) showed an overall increasing tendency from 0.42 to 0.58. The quantum efficiencies of P(ADN‐co‐VK) decreased from 0.36 to 0.19 with an increase of VK fraction. With increasing S/VK content, the highest occupied molecular orbital of P(ADN‐co‐S)/P(ADN‐co‐VK) ranged from −5.58 to −5.73 eV, which was similar to that of P(ADN) (−5.71 eV). The band gaps of P(ADN‐co‐S) and P(ADN‐co‐VK) were about 2.97 eV, which were equal to that of P(ADN), and smaller than that of 2‐methyl‐9,10‐di(1‐naphthalenyl)anthracene (MADN) (3.04 eV) and poly(9‐vinylcarbazole) (3.54 eV). Preliminary electroluminescence results were obtained for a homojunction device with the configuration ITO/MoO3 (20 nm)/P(ADN)/LiF (1 nm)/Al (100 nm), which achieved only 30–50 cd m−2, due to P(ADN) having a low mobility of 4.7 × 10−8 cm2 V−1 s−1 compared to that of its model compound MADN of 6.5 × 10−4 cm2 V−1 s−1. © 2013 Society of Chemical Industry

Diarylfluorene Flexible Pendant Functionalization of Polystyrene for Efficient and Stable Deep-Blue Polymer Light-Emitting Diodes

“…35,38−41 For the deep-blue luminescent materials, the formation of these interchain-excited states results in lower luminescence efficiency, poor color purity, and unstable luminescence, 39,42−44 which are undesirable for OLEDs. 45,46 Even weak intermolecular electron coupling, dense packing of the chromophores, may significantly influence the large planar aromatic geometry, altering the color purity and the emission efficiency. In the past, we designed and prepared a steric diarylfluorene emitter MC8TPA (Scheme 1) for OLEDs.…”

“…In addition, this physical blending may result in random intermolecular aggregation of active molecules, which also induce severe electronic coupling, polaron formation, charge trapping, and exciton–exciton annihilation in the solid state. Therefore, the efficient distribution of emissive molecule units into a PS matrix via a chemical method suppresses phase separation and improves morphological stability and emission efficiency for optoelectronic applications. ,− However, the direct bonding of a large planar aromatic chromophore as a side substitute into the PS main chain also causes serious electron coupling or charge transfer between the adjacent pendant chromophore along the PS main chain, leading to excimer emission, polaron formation, and exciton–exciton annihilation (Scheme a). ,− For the deep-blue luminescent materials, the formation of these interchain-excited states results in lower luminescence efficiency, poor color purity, and unstable luminescence, ,− which are undesirable for OLEDs. , Even weak intermolecular electron coupling, dense packing of the chromophores, may significantly influence the large planar aromatic geometry, altering the color purity and the emission efficiency. In the past, we designed and prepared a steric diarylfluorene emitter MC8TPA (Scheme ) for OLEDs .…”