Efficient multilayer electroluminescence devices with poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) as the emissive layer

Abstract

The use of a new highly luminescent conjugated polymer as an emissive layer in single and multilayer electroluminescence devices is reported. Poly(m-phenylenevinylene-co-2,5 -dioctyloxy-p-phenylenevinylene) [PmPV-co-DOctOPV] was prepared via a Wittig synthesis reaction. The resulting polymer has a high photoluminescence quantum efficiency in the solid state with an emission spectrum peaked at 506 nm (2.45 eV) in the green. Electroluminescence devices were fabricated with an ITO anode and a MgAg cathode. Three different structures were studied: (i) single layer devices containing only PmPV-co-DOctOPV; (ii) double layer devices with PmPV-co-DOctOPV and an evaporated film of 1,3-bis(4-tert-butylphenyl-1,3,4-oxadiazoyl) phenylene [OXD-7] as an electron transport layer; (iii) triple layer devices containing PmPV-co-DOctOPV, OXD-7 and in addition a polyvinylcarbazole hole transport layer. Electroluminescence external quantum efficiencies for these devices were found to be up to 0.08%, 0.55%, and 1%, respectively, corresponding to luminous efficiencies of ≈0.5, ≈3, and ≈6 lm/W and power efficiencies of 8.5×10−5, 5.9×10−4, and 6.0×10−4 W/W.

Controlling the optical properties of a conjugated co-polymer through variation of backbone isomerism and the introduction of carbon nanotubes

“…Previously, it was shown that the change in backbone configuration blue shifts the absorption and luminescence as expected [13][14]. It may also be expected that the geometry of the backbone reduce the distances over which phonons can propagate.…”

Alternating and direct current characterization and photoinduced absorption studies of modified conjugated polymer thin films

“…A blue shift of the absorption and PL maxima compared to the corresponding all paraphenylenevinylene copolymer has been observed. 11 The PmPV used in this work was synthesized by the Organic Materials Synthesis section of Materials Ireland Polymer Research Center in Trinity College Dublin. 12 Two different synthesis reactions have been used with three solvents to give six different synthesis pathways for the polymer.…”

Solution processed naphthalene diimide derivative as electron transport layers for enhanced brightness and efficient polymer light emitting diodes

“…Since PLEDs require injection of both electrons and holes into the active material, balancing charge flow is essential to increase device efficiency. [2] The majority of electroluminescent polymers used as active materials have higher hole mobilities than electron mobilities, in addition to an incompatibility between their low LUMO levels and the high work function metallic cathodes used. [3,4] Thus significant interest towards increasing charge flow balance has focused on improving electron injection at the cathode/polymer interface.…”