High efficiency warm white phosphorescent organic light emitting devices based on blue light emission from a bipolar mixed-host

• Published in: Organic electronics Vol. 45; pp. 273 - 278
• Main Authors: Chen, Chen, Liu, Yun-fei, Chen, Zheng, Wang, Hao-ran, Wei, Meng-zhu, Bao, Cong, Zhang, Gang, Gao, Yong-Hui, Liu, Chun-Ling, Jiang, Wen-Long, Duan, Yu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2017
• Subjects: Bipolar mixed-host; Blue emission; Exciplex; PH-WOLEDs; Exciplex; Blue emission; Bipolar mixed-host; PH-WOLEDs
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2017.03.027

In this study, we demonstrate a high-efficiency and low turn-on voltage warm white phosphorescent organic light emitting devices (PH-WOLEDs) based on a blue mixed-host emission layer (EML) and an orange ultrathin layer. The device has a simple structure and would simplify the fabrication process and reduce fabrication costs. The concept is based on the design a high-efficiency blue mixed-host EML, using an electron-transport material, 4,6-Bis(3,5-di(pyridin-4-yl) phenyl)-2-(3-(pyridin-3-yl) phenyl) pyrimidine (B4PYMPM) to enhance the carrier balance ability of the hole-transport material 1,3-Bis(carbazol-9-yl) benzene (MCP) which operates as the mixed-host and when the MCP: B4PYMPM ratio in the mixed-film was 4:1 got better effects. Based on the blue EML, we realized WOLEDs, characterized by a peak power efficiency of 71.3 lm/W at 3.1 V and a low turn-on voltage of 2.65 V. The mixed-host blue EML exhibited a much higher performance compared to the MCP host. Stable warm white light emission with Commission International de L'Eclairage (CIE) coordinates from (0.37, 0.45) to (0.38, 0.47) for a luminance value ranging from 1000 to 10,000 cd/m2 was obtained. [Display omitted] •Firstly introduced MCP and B4PYMPM and their application in OLEDs and get peak power efficiency of 71.3 lm/W for WOLEDs.•We have successfully demonstrated efficient blue OLEDs which used MCP and B4PYMPM as the mixed-host with a maximum efficiency of 27.30 lm/W (29.24 cd/A).•Based on the blue EML, we realized WOLEDs, characterized by a peak power efficiency of 71.3 lm/W at 3.1 V and a low turn-on voltage of 2.65 V.