Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime

• Published in: Synthetic metals Vol. 162; no. 3-4; pp. 398 - 401
• Main Authors: Yang, Qian, Hao, Yuying, Wang, Zhenguo, Li, Yunfei, Wang, Hua, Xu, Bingshe
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2012; Elsevier
• Subjects: Applied sciences; Compound structure devices; Doped charge transport layers; Double emission layers; Electronics; Exact sciences and technology; High efficiency; Long lifetime; Optoelectronic devices; Phosphorescent OLED; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Long lifetime; Doped charge transport layers; Double emission layers; High efficiency; Phosphorescent OLED; Performance evaluation; Electron transport layer; High density; Charge transport; Aluminium complex; Tin addition; Optoelectronic device; Phosphorescence; Current density; Double layers; Organic electronics; Heterojunction; High strength current; Lithium fluoride; Iridium complex; Doped materials; Durability; Indium oxide; Light emitting diode; Organic light emitting diodes; Reliability
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2011.12.027

► LiF-doped TPBi as electron transport layer. ► Electrophosphorescent organic light-emitting diodes based on double-emitting layers. ► The efficiency and operational lifetime are remarkably improved. ► The device shows better stability at high current density. We demonstrate an excellent electrophosphorescent organic light-emitting diodes (PHOLEDs) with double-emitting layers (D-EML) and LiF-doped TPBi as electron transport layer (ETL), which has the structure of ITO/NPB (30nm)/CBP:Ir(ppy)3 (20nm)/TPBi:Ir(ppy)3 (10nm)/TPBi (10nm)/TPBi:LiF (40nm)/LiF (1.2nm)/Al (150nm). A peak current efficiency of 40.5cd/A and a maximum power efficiency of 23.7lm/W have been achieved, 1.99 and 2.95 times of those of the reference device [ITO/NPB (30nm)/CBP:Ir(ppy)3 (30nm)/TPBi (10nm)/Alq3 (40nm)/LiF (1.2nm)/Al (150nm)], respectively. And the device shows better stability than reference device at high current density. Moreover, the operational lifetime is improved, nearly 35 times of that of the reference device. We attribute mainly these improvement to the carriers’ self-balancing character of D-EML OLEDs, less numbers of heterojunction interface and better electron transport property of TPBi:LiF.