White organic light-emitting diodes with an ultra-thin premixed emitting layer

THIN SOLID FILMS

卷:542

Article

Jeon, T.¹  Geffroy, B.^1,2  Tondelier, D.¹  Bonnassieux, Y.¹  Forget, S.^3,5  Chenais, S.^3,5  Ishow, E.⁴ 

[1] Ecole Polytech, CNRS, UMR 7647, LPICM, F-91128 Palaiseau, France

[2] CEA Saclay, DSM IRAMIS SPCSI LCSI, F-91191 Gif Sur Yvette, France

[3] Univ Paris 13, Phys Lasers Lab, F-93430 Villetaneuse, France

[4] ENS Cachan, CNRS, UMR 8531, PPSM, F-94235 Cachan, France

[5] LPL, CNRS, UMR 7538, F-93430 Villetaneuse, France

关键词: White organic light emitting diodes;    Mixed emitting layer;    Exciton diffusion;    Resonant energy transfer;    Starbust triphenylamine;   

DOI  :  10.1016/j.tsf.2013.06.054

来源: Elsevier

【 摘 要 】

We described an approach to achieve fine color control of fluorescent White Organic Light-Emitting Diodes (OLED), based on an Ultra-thin Premixed emitting Layer (UPL). The UPL consists of a mixture of two dyes (red-emitting 4-di(4'-tert-butylbiphenyl-4-yl)amino-4'-dicyanovinylbenzene or fvin and green-emitting 4-di(4'-tert-butylbiphenyl-4-yl)aminobenzaldehyde or fcho) premixed in a single evaporation cell: since these two molecules have comparable structures and similar melting temperatures, a blend can be evaporated, giving rise to thin films of identical and reproducible composition compared to those of the pre-mixture. The principle of fine color tuning is demonstrated by evaporating a 1-nm-thick layer of this blend within the hole-transport layer (4,4'-bis[N-(1-naphtyl)-N-phenylamino]biphenyl (alpha-NPB)) of a standard fluorescent OLED structure. Upon playing on the position of the UPL inside the hole-transport layer, as well as on the premix composition, two independent parameters are available to finely control the emitted color. Combined with blue emission from the heterojunction, white light with Commission Internationale de l'Eclairage 1931 color coordinates (0.34, 034) was obtained, with excellent color stability with the injected current. The spectrum reveals that the fcho material does not emit light due to efficient energy transfer to the red-emitting fvin compound but plays the role of a host matrix for fvin, allowing for a very precise adjustment of the red dopant amount in the device. (C) 2013 Elsevier B.V. All rights reserved.

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