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

Jochen Bruckbauer, Catherine Brasser, Neil J. Findlay, Paul R. Edwards, David J. Wallis, Peter J. Skabara, Robert W. Martin

Research output: Contribution to journalArticle

8 Citations (Scopus)
113 Downloads (Pure)

Abstract

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.
Original languageEnglish
Article number405103
Number of pages9
JournalJournal of Physics D: Applied Physics
Volume49
Issue number40
Early online date12 Sep 2016
DOIs
Publication statusPublished - 12 Oct 2016

Fingerprint

Organic light emitting diodes (OLED)
Light emitting diodes
light emitting diodes
Tuning
tuning
Color
color
Molecules
converters
Conversion efficiency
molecules
down-converters
Phosphors
Quenching
Agglomeration
phosphors
Fabrication
Degradation
quenching
degradation

Keywords

  • light-emitting diode
  • energy efficiencey
  • organic converter
  • colour converter
  • hybrid white LED
  • inorganic blue LED

Cite this

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title = "Colour tuning in white hybrid inorganic/organic light-emitting diodes",
abstract = "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.",
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Colour tuning in white hybrid inorganic/organic light-emitting diodes. / Bruckbauer, Jochen; Brasser, Catherine; Findlay, Neil J.; Edwards, Paul R.; Wallis, David J.; Skabara, Peter J.; Martin, Robert W.

In: Journal of Physics D: Applied Physics, Vol. 49, No. 40, 405103, 12.10.2016.

Research output: Contribution to journalArticle

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T1 - Colour tuning in white hybrid inorganic/organic light-emitting diodes

AU - Bruckbauer, Jochen

AU - Brasser, Catherine

AU - Findlay, Neil J.

AU - Edwards, Paul R.

AU - Wallis, David J.

AU - Skabara, Peter J.

AU - Martin, Robert W.

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