Highly efficient flexible organic light-emitting devices utilizing F4-TCNQ/m-MTDATA multiple quantum well structures

Flexible organic light-emitting devices (FOLEDs) based on multiple quantum well (MQW) structures, which consist of alternate layers of 2,3,5,6-Tetrafluoro-7,7,8,8,-tetracyano-quinodimethane (F4-TCNQ) and 4,4',4 '' tris-(3-methylphenylphe-nylamino)tripheny-lamine (m-MTDATA) have been fabricated. The Alq3-based device with double quantum well (DQW) structure exhibits the remarkable electroluminescent (EL) performances for the brightness of 23,500 cd/m(2) at 14 V and the maximum current efficiency of 7.0 cd/A at 300.3 mA/cm(2), respectively, which are greatly improved by 114% and 56% compared with the brightness of 10,958 cd/m(2) at 14 V and the maximum current efficiency of 4.5 cd/A at 174.0 mA/cm(2) for the conventional device without MQW structures. These results demonstrate that the EL performances of FOLEDs could be greatly improved by utilizing the novel MQW structures, and the reason for this improvement has also been explained by the effect of interfacial dipole and interfacial doping between F4-TCNQ and m-MTDATA in this article. (C) 2012 Elsevier B.V. All rights reserved.