Yi-Lin WuChien-Yu ChenYi-Hsiang HuangYin-Jui LuCheng-Hsu ChouCHUNG-CHIH WU2018-09-102018-09-102014-08http://scholars.lib.ntu.edu.tw/handle/123456789/388689https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942374453&doi=10.1364%2fAO.53.0000E1&partnerID=40&md5=32b24d2204df151814069af4a7d73510In this work, we conducted studies of tandem organic light-emitting devices (OLEDs) based on the connecting structure consisting of n-doped electron-transport layer (n-ETL)/1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN)/hole-transport layer. We investigated effects of different n-ETL materials and different HATCN thicknesses on characteristics of tandem OLEDs. Results show that the tandem OLEDs with n-BPhen and a 20 nm layer of HATCN in the connecting structure exhibited the best performance. With these, highly efficient and bright green phosphorescent two-emitting-unit tandem OLEDs, with drive voltages significantly lower than twice that of the single-unit benchmark device and current efficiencies higher than twice that of the single-unit benchmark device, were demonstrated. © 2014 Optical Society of America.Current density; Doping (additives); Electron transport properties; Light emission; Current efficiency; Drive voltage; Electron transport layers; N-doped; Organic light-emitting devices; Structure-based; Organic light emitting diodes (OLED)journal article10.1364/AO.53.0000E12-s2.0-84942374453WOS:000340824800004