Processable variable band gap conjugated polymers for optoelectronic devices.

摘要

Solution processable variable band gap thienylene-based conjugated polymers were designed for application in various optoelectronic devices. The synthesis of wide band gap regiosymmetric thiophene-dialkoxybenzene and 3,4-ethylenedioxythienyl-dialkoxybenzene polymers was investigated, and organo-soluble isoregic poly(1,4-bis(2-thienyl)-2,5-dialkoxybenzenes) (PBT-B(OR)2) were successfully synthesized via Yamamoto coupling, with estimated number average molecular weights ranging from 3,000 to 5,000 g mol-1, and a solubility of about 7 mg mL-1 in toluene. 1,4-Bis[2-(3,3-dialkyl-(3,4-propylenedioxy)thienyl]-2,5-didodecyloxybenzene derivatives, [BProDOT-R2-B(OC12H25) 2)], were prepared by Negishi coupling of the ProDOT and didodecyloxybenzene units in ca. 40% yields. They were efficiently electropolymerized to form electroactive films exhibiting redox switching at fairly low potentials (∼ +0.1 V vs. Fc/Fc+). BProDOT-Hex2-B(OC 12H25)2 was polymerized via ferric chloride chemical oxidation with an estimated number average molecular weight of 14,600 g mol -1. A solubility of 15 mg mL-1 in chloroform was reached, which is attributed to the ProDOT hexyl substituents.; Four analogues of the narrow band-gap poly(3,4-propylenedioxythiophene-dialkyl)-cyano- p-phenylene vinylene (PProDOT-R2:CNPPV) polymer family have been synthesized via Knoevenagel condensation with number average molecular weights ranging between 9,000 and 24,000 g mol-1. Linear and branched alkoxy substituents were introduced along the polymer backbone yielding organo-soluble materials (15 mg mL-1 in chloroform) with improved film quality and variable optical properties.; Conjugated polyelectrolytes were successfully synthesized from the ferric chloride oxidative polymerization of amino-substituted ProDOTs, followed by post-polymerization quaternization of the amino substituents. These materials, well solvated in DMSO, are presently the most fluorescent red-shifted polyelectrolytes ever reported.; The optical, redox, and electronic properties of the polymers were studied by electrochemical and spectroscopic methods. Owing to their solubility properties, the polymers could be processed into homogeneous thin-films by spin-coating or spray-casting, and applied to light-emitting diodes and photovoltaic devices. Particularly when used as electron donors in tandem with the electron acceptor [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) in bulk heterojunction photovoltaic devices, PBT-B(OR)2 polymers exhibited power conversion efficiencies up to ∼0.6%. PBProDOT-Hex2-B(OC12H 25)2 cathodically switched between orange and highly transmissive gray colors, and the PProDOT-R2:CNPPV polymers switched between neutral blue/purple states and transmissive gray oxidized and reduced states, which makes them attractive for large area electrochromic displays.