Room-temperature multiple phosphorescence from functionalized corannulenes : temperature sensing and afterglow organic light-emitting diode

Abstract

Corannulene-derived materials have been extensively explored in energy storage and solar cells, but, however, are rarely documented as emitters in light-emitting sensors and organic light-emitting diodes (OLEDs), due to low exciton utilization. Here, we report a family of multi-donor and acceptor (multi-D-A) motifs, TCzPhCor, TDMACPhCor, and TPXZPhCor, using corannulene as the acceptor and carbazole (Cz), 9,10-dihydro-9,10-dimethylacridine (DMAC), and phenoxazine (PXZ) as the donor, respectively. By decorating corannulene with different donors, multiple phosphorescence is realized. Theoretical and photophysical investigations reveal that TCzPhCor shows room-temperature phosphorescence (RTP) from the lowest-lying T1; however, for TDMACPhCor, dual RTP originating from a higher-lying T1 (T1H) and a lower-lying T1 (T1L) can be observed, while for TPXZPhCor, T1H-dominated RTP occurs resulting from a stabilized high-energy T1 geometry. Benefiting from the high-temperature sensitivity of TPXZPhCor, high color-resolution temperature sensing is achieved. Besides, due to degenerate S1 and T1H states of TPXZPhCor, the first corannulene-based solution-processed afterglow organic light-emitting diodes (OLEDs) is investigated. The afterglow OLED with TPXZPhCor shows a maximum external quantum efficiency (EQEmax) and a luminance (Lmax) of 3.3% and 5167 cd m-2, respectively, which is one of the most efficient afterglow RTP OLEDs reported to date.