A poly(urethane)-encapsulated benzo[2,3-d:6,7-d']diimidazole organic down-converter for green hybrid LEDs

Wiles, Alan A. and Bruckbauer, Jochen and Mohammed, Nabeel and Cariello, Michele and Cameron, Joseph and Findlay, Neil J. and Taylor-Shaw, Elaine and Wallis, David J. and Martin, Robert W. and Skabara, Peter J. and Cooke, Graeme (2020) A poly(urethane)-encapsulated benzo[2,3-d:6,7-d']diimidazole organic down-converter for green hybrid LEDs. Materials Chemistry Frontiers, 4 (3). pp. 1006-1012.

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    Abstract

    The development of organic down-converting materials continues to attract attention in hybrid LED technology by obviating the need for non-sustainable rare-earth elements. In this work, a benzodiimidazole-based system (TPA-BDI) has been employed as a down-converting layer in a hybrid organic-inorganic LED device. A commercially available poly(urethane)-based resin is used as the encapsulating material, providing a dilute layer of TPA-BDI that is deposited on top of the GaN-based LED. Crucially, the solution-state emissive performance is generally maintained when encapsulated at low concentrations within this resin. A maximum luminous efficacy of 87 lm W -1 was demonstrated using a 1.0 mg ml -1 concentration of TPA-BDI in the resin. The suitability of using organic down-converters to produce green light from hybrid devices was demonstrated by the excellent repeatability of the device characteristics across a series of encapsulated LEDs.