Electrochemiluminescence energy transfer in mixed iridium-based redox copolymers immobilised as nanoparticles

Energy transfer in a redox metallopolymer containing both fluorinated and non-fluorinated cyclometalated iridium (II) centres is explored. These materials are readily prepared by mixing two different iridium dimers and a backbone chain containing pendant groups (e.g. poly-vinylpyridine/poly-styrene), which can coordinate to the metal centres. Their easy synthesis together with their ability to self-assemble into polymeric nanoparticles in aqueous media render them a unique emitting material with nanoscale dimensions. We report the photophysical, electrochemical and electrochemiluminescence (ECL) properties of these polymeric nanoparticles in solution and immobilised as a thin layer. We demonstrate Dexter-type Energy Transfer (ET) and ECL-ET phenomena resulting in ECL enhancement by up to 505% compared with metallopolymers containing only one type of iridium centre. These results demonstrate the possibility of synthesising new materials with tailored and enhanced emission wavelengths by careful selection of the emitting centres for any opto-electronic and sensing-related applications. (C) 2019 Elsevier Ltd. All rights reserved.