The Study of N-type Doping and Stamping Transfer Processes of Electron Transport Layer for Organic Light-emitting Diodes

Fuh-Shyang JUANG  Apisit CHITTAWANIJ  Lin-Ann HONG  Yu-Sheng TSAI  Kuo-Kai HUANG  

IEICE TRANSACTIONS on Electronics   Vol.E98-C   No.2   pp.66-72
Publication Date: 2015/02/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E98.C.66
Type of Manuscript: INVITED PAPER (Special Section on Recent Progress in Organic Molecular Electronics)
OLEDs,  n-type OLEDs,  ETL,  Solution process,  Stamping process,  

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This paper presents 2-(hydroxyl) quinoline lithium (Liq) used as an n-type dopant to improve white hybrid organic light-emitting diode (WHOLEDs) performance. The Liq doped tris(8-hydroxyquinolinato) aluminum (Alq3) layer possessed enhanced electron injection, efficient hole and electron balance in the emitting layer, as one of the most essential issues for device applications. This work investigates the optimum recipe (Liq concentration and thickness) of Alq3:Liq n-type doped electron injection layer (EIL) for WHOLED devices by comparing the current density and efficiency results with conventional Alq3/LiF technique. A blocking layer or interlayer is inserted between emitting layer and EIL to avoid excitons quenched. In this work suitable material and optimum thickness for blocking layer are studied, a white small-molecular organic light-emitting diode (SM-OLEDs) based on a 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBi) stamping transfer process is investigated. The proposed stamping transfer process can avoid the complexity of the vacuum deposition process.