The degradation mechanism of blue thermally activated delayed fluorescence (TADF) organic light-emitting Diodes (OLEDs) was demonstrated by distinguishing the triplet emitters into three species. To investigate the dependency of the device stability on the T 1 state characterization of TADF emitters, three new bipolar compounds named 9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (BCz-TRZ), 2-(9'-phenyl-9H,9'H-[3,3'-bicarbazol]-9-yl)dibenzo[b,d]thiophene 5,5-dioxide (BCz-DBTO), and 10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-diphenyl-9,10-dihydroacridine (DPAC-TRZ) were designed and synthesized, and investigated along with a reported blue TADF compound 9'-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9'H-9,3':6',9'-tercarbazole (3Cz-TRZ). These four CT emitters exhibit similar emission spectra with peaks at 480?490 nm in a 10-wt%-doped film of bis (2-(diphenylphosphino)phenyl)ether oxide (DPEPO). The triplet spin density of DPACTRZ is delocalized across the entire molecule, indicating the CT nature of the temperature state of DPAC-TRZ. On the basis of our degradation mechanism of blue TADF OLEDs, the devices employing BCz-TRZ should be more stable than those employing the other three emitters.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering