Pyrene functioned diarylfluorenes as efficient solution processable light emitting molecular glass

In this paper, we described a new category of solution processable small molecule organic light emitting materials, the pyrene functioned diarylfluorenes: 2PE-PPF and DPE-PPF. They emit blue light in solution and green light in film, and show high thermal stability with the 5% weight loss temperature (Td) over 400 °C. The glass transition temperature (Tg) for 2PE-PPF and DPE-PPF is 102 °C and 147 °C, respectively. These molecules are interesting molecular glass and they have good film forming abilities. Smooth and uniform film could be obtained by spin-coating. This character enables them able to be used in solution processed OLEDs by spin-coating or jet-printing. Single layered device using 2PE-PPF as the active material shows a turn-on voltage of 3.2 V, brightness over 8000 cd/m2 and current efficiency up to 2.55 cd/A. Double layered device by inserting TPBI as the hole-blocking electron-transporting layer increases the maximum efficiency to 5.83 cd/A.