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The role of LiF buffer layer in tris‐(8‐hydroxyquinoline) aluminum‐based organic light‐emitting devices with Mg:Ag cathode
Author(s) -
Chen B. J.,
Tan S. C.,
Sun X. W.
Publication year - 2005
Publication title -
journal of the society for information display
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 52
eISSN - 1938-3657
pISSN - 1071-0922
DOI - 10.1889/1.1927737
Subject(s) - citation , layer (electronics) , tris , computer science , physics , library science , nanotechnology , chemistry , materials science , biochemistry
— The device characteristics of organic light‐emitting devices based on tris‐(8‐hydroxyqunoline) aluminum with a thin layer of LiF inserted at the ITO and organic interface or organic and Mg:Ag cathode interface were investigated. A thin layer of LiF can enhance the electron injection when it was inserted only between the organic electron‐transporting layer and the Mg:Ag alloy cathode, but can block hole injection when inserted between the ITO anode and the organic hole‐transport layer. By inserting both a 1.0‐nm LiF layer at side of the ITO anode and a 0.5‐nm LiF layer under the Mg:Ag cathode, the device, at a current injection of 10 mA/cm 2 , exhibited the highest current efficiency of 8.2 cd/A and power efficiency of 1.93 lm/W for all the types of devices investigated in this study. Both the current efficiency and power efficiency of the device were improved by 1.2 times at a current injection of 10 mA/cm 2 , compared to the standard device without any LiF buffer layer. This is due to the increased electron injection and decreased hole injection that off‐sets the imbalance of electron and hole injection and brings it towards the balanced injection of electrons and holes, thus reducing the non‐productive hole current.