Colour tuning in white hybrid inorganic/organic light-emitting diodes

Bruckbauer, J., Brasser, C., Findlay, N. J. , Edwards, P. R., Wallis, D. J., Skabara, P. J. and Martin, R. W. (2016) Colour tuning in white hybrid inorganic/organic light-emitting diodes. Journal of Physics D: Applied Physics, 49(40), 405103. (doi: 10.1088/0022-3727/49/40/405103)

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White hybrid inorganic/organic light-emitting diodes (LEDs) were fabricated by combining a novel organic colour converter with a blue inorganic LED. An organic small molecule was specifically synthesised to act as down-converter. The characteristics of the white colour were controlled by changing the concentration of the organic molecule based on the BODIPY unit, which was embedded in a transparent matrix, and volume of the molecule and encapsulant mixture. The concentration has a critical effect on the conversion efficiency, i.e. how much of the absorbed blue light is converted into yellow light. With increasing concentration the conversion efficiency decreases. This quenching effect is due to aggregation of the organic molecule at higher concentrations. Increasing the deposited amount of the converter does not increase the yellow emission despite more blue light being absorbed. Degradation of the organic converter was also observed during a period of 15 months from LED fabrication. Angular-dependent measurements revealed slight deviation from a Lambertian profile for the blue and yellow emission peaks leading to a small change in 'whiteness' with emission angle. Warm white and cool white light with correlated colour temperatures of 2770 K and 7680 K, respectively, were achieved using different concentrations of the converter molecule. Although further work is needed to improve the lifetime and poor colour rendering, these hybrid LEDs show promising results as an alternative approach for generating white LEDs compared with phosphor-based white LEDs.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Skabara, Professor Peter and Findlay, Dr Neil
Authors: Bruckbauer, J., Brasser, C., Findlay, N. J., Edwards, P. R., Wallis, D. J., Skabara, P. J., and Martin, R. W.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of Physics D: Applied Physics
Publisher:IOP Publishing
ISSN (Online):1361-6463
Published Online:12 September 2016
Copyright Holders:Copyright © 2016 IOP Publishing Ltd
First Published:First published in Journal of Physics D: Applied Physics 49(40):405103
Publisher Policy:Reproduced under a Creative Commons License

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