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Highly Efficient Warm White Organic Light‐Emitting Diodes by Triplet Exciton Conversion
Author(s) -
Chang YiLu,
Song Yin,
Wang Zhibin,
Helander Michael G.,
Qiu Jacky,
Chai Lily,
Liu Zhiwei,
Scholes Gregory D.,
Lu Zhenghong
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201201858
Subject(s) - phosphor , incandescent light bulb , color rendering index , optoelectronics , oled , materials science , diode , quantum efficiency , light emitting diode , exciton , rendering (computer graphics) , solid state lighting , efficient energy use , optics , nanotechnology , computer science , physics , electrical engineering , computer graphics (images) , layer (electronics) , quantum mechanics , engineering
White organic light‐emitting diodes (WOLEDs) are currently under intensive research and development worldwide as a new generation light source to replace problematic incandescent bulbs and fluorescent tubes. One of the major challenges facing WOLEDs has been to achieve high energy efficiency and high color rendering index simultaneously to make the technology competitive against other alternative technologies such as inorganic LEDs. Here, an all‐phosphor, four‐color WOLEDs is presented, employing a novel device design principle utilizing molecular energy transfer or, specifically, triplet exciton conversion within common organic layers in a cascaded emissive zone configuration to achieve exceptional performance: an 24.5% external quantum efficiency (EQE) at 1000 cd/m 2 with a color rendering index (CRI) of 81, and an EQE at 5000 cd/m 2 of 20.4% with a CRI of 85, using standard phosphors. The EQEs achieved are the highest reported to date among WOLEDs of single or multiple emitters possessing such high CRI, which represents a significant step towards the realization of WOLEDs in solid‐state lighting.