Fluorene–Triphenylamine-Based Bipolar Materials: Fluorescent Emitter and Host for Yellow Phosphorescent OLEDs

• Main Authors: Ramanaskanda Braveenth, Hasu Jung, Keunhwa Kim, Bo Mi Kim, Il-Ji Bae, Miyoung Kim, Kyu Yun Chai
• Format: Article
• Language: English
• Published: MDPI AG 2020-01-01
• Series: Applied Sciences
• Subjects: organic light-emitting diodes; fluorene; host material; triazine; pyrimidine
• Online Access: https://www.mdpi.com/2076-3417/10/2/519

In this study, two new bipolar materials were designed and synthesized: <i>N</i>¹-(9,9-diphenyl-9<i>H</i>-fluoren-2-yl)-<i>N</i>¹-(4,6-diphenylpyrimidin-2-yl)-<i>N</i>⁴,<i>N</i>⁴-diphenylbenzene-1,4-diamine (FLU-TPA/PYR) and <i>N</i>¹-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-<i>N</i>¹-(9,9-diphenyl-9<i>H</i>-fluoren-2-yl)-<i>N</i>⁴,<i>N</i>⁴ diphenylbenzene-1,4-diamine (FLU-TPA/TRZ). We fabricated two different devices, namely a yellow phosphorescent organic light-emitting diode (PhOLED) and a non-doped fluorescent OLED emitter with both FLU-TPA/PYR and FLU-TPA/TRZ. The FLU-TPA/PYR host-based yellow PhOLED device showed better maximum current, power and external quantum efficiencies at 21.70 cd/A, 13.64 lm/W and 7.75%, respectively. The observed efficiencies were better than those of the triazine-based FLU-TPA/TRZ. The non-doped fluorescent device with the triazine-based FLU-TPA/TRZ material demonstrated current, power and external quantum efficiencies of 10.30 cd/A, 6.47 lm/W and 3.57%, respectively.