Efficient cathode contacts through Ag-doping in multifunctional strong nucleophilic electron transport layer for high performance inverted OLEDs

• Published in: Organic electronics Vol. 89; p. 106031
• Main Authors: Yang, Hye In, Jeong, Seung Hye, Cho, Sang Min, Lampande, Raju, Lee, Kyu-Myung, Hong, Jong-Am, Choi, Ji-Woong, Kim, Beom-su, Park, Yongsup, Pode, Ramchandra, Kwon, Jang Hyuk
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2021
• Subjects: Electron-injection; Green inverted OLED; Inverted OLED; Silver doping; Stable inverted OLED; Stable inverted OLED; Electron-injection; Inverted OLED; Green inverted OLED; Silver doping
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2020.106031

This paper presents an efficient and stable green inverted organic light emitting diode (IOLED) using multifunctional and strong nucleophilic quality electron transport material (1,3-bis(2-phenyl-1,10-phenanthrolin-4-yl)benzene (m-bPPhenB)) with silver (Ag) as an n-dopant. By the energy level alignment study using in-situ ultraviolet photoelectron spectroscopy measurement, negligible electron injection barrier between indium tin oxide (ITO) and Ag-doped m-bPPhenB (Φe ≈ 0.03 eV) is observed and the electrons can be easily tunneled from ITO into Ag-doped m-bPPhenB layer. Also, Ag dopant forms coordination bonds with phenanthroline based unit, which improves electron injection from ITO. Fabricated IOLED devices using an Ag-doped m-bPPhenB have an extremely low driving voltage of 3.6 V and external quantum efficiency of 29.0%. Such good performances of IOLED are attributed to negligible electron injection barrier at the interface between ITO and Ag-doped m-bPPhenB. The Ag-doped IOLED device also shows a good air stability owing to the stable Ag n-dopant. The doping of Ag into special electron transport layer in the IOLED structure could be applicable to various displays and lighting applications. [Display omitted] •We fabricated efficient and stable green IOLEDs by using m-bPPhenB:Ag ETL.•A negligible electron injection barrier observed between ITO and m-bPPhenB:Ag.•IOLED showed low driving voltage, high EQE, and good stability.