Highly Efficient Electron‐Transporting/Injecting and Thermally Stable Naphthyridines for Organic Electrophosphorescent Devices. (18th October 2012)

• Record Type: Journal Article
• Authors: Xiao, Lixin; Xing, Xing; Chen, Zhijian; Qu, Bo; Lan, Hsinglin; Gong, Qihuang; Kido, Junji
• Is Part Of: Advanced functional materials. Volume 23:Number 10(2013)
• Page Start: 1323
• Page End: 1330
• Publication Date: 2012-10-18
• Subjects: Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201202194
• Languages: English
• ISSNs: 1616-301X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A series of 1, 8‐naphthyridine derivatives is synthesized and their electron‐transporting/injecting (ET/EI) properties are investigated via a multilayered electrophosphorescent organic light‐emitting device (OLED) using <italic>fac</italic>‐tris(2‐phenylpyridine)iridium [Ir(ppy)<sub>3</sub>] as a green phosphorescent emitter doped into a 4, 4′‐<italic>N</italic>, <italic>N</italic>′‐dicarbazolebiphenyl (CBP) host with 4, 4′‐bis[<italic>N</italic>‐(1‐naphthyl)‐<italic>N</italic>‐phenylamino]biphenyl (<italic>a</italic>‐NPD) as the hole‐transporting layer, and poly(arylene ether sulfone) containing tetraphenylbenzidine (TPDPES) doped with tris(4‐bromophenyl)ammonium hexachloroantimonate (TBPAH) as the hole‐injecting layer. The turn‐on voltage of the device is 2.5 V using 2, 7‐bis[3‐(2‐phenyl)‐1, 8‐naphthyridinyl]‐9, 9‐dimethylfluorene (DNPF), lower than that of 3.0 V for the device using a conventional ET material. The maximum current efficiency (CE) and power efficiency (PE) of the DNPF device are much higher than those of a conventional device. With the aid of a hole‐blocking (HB) and exciton‐blocking layer of bathocuproine (BCP), 13.2–13.7% of the maximum external quantum efficiency (EQE) and a maximum PE of 50.2–54.5 lm W<sup>−1</sup> are obtained using the naphthyridine derivatives; these values are comparable with or even higher than the 13.6% for conventional ET material. The naphthyridine derivatives show high thermal stabilities, glass‐transition temperatures much higher than that of aluminum(III) bis(2‐methyl‐8‐quinolinato)‐4‐phenylphenolate (BAlq), and decomposition temperatures of 510–518 °C, comparable to or even higher than those of Alq<sub>3</sub>.</p> </abstract>