Design Strategy of Decorating Phenylcarbazole with a Donor and Acceptor for Blue‐Shifted Emission in Thermally Activated Delayed Fluorescent Emitters

Abstract

As eries of blue thermally activated delayedf luorescent( TADF)e mitters of 1''-(4,6-diphenyl-1,3,5-triazin-2-yl)-9,9''-diphenyl-9H,9''H-3,3':9',4''-tercarbazole (TrzCz1) and 3',6'-di-tert-butyl-1-(4,6-diphenyl-1,3,5-triazin-2-yl)-9-phenyl-9H-4,9'-bicarbazole (TrzCz2) were synthesized through am olecular design approach to decorate phenylcarbazole with a donor and an acceptor. The 1-and 4-positions of the phenylcarbazole core were modified with adiphenyltriazine acceptor and abicarbazole or tert-butylcarbazole donor,respectively,t hrough as ynthetic strategyt oi ntroduce Br at the 1-position and Fa tt he 4-position. The TrzCz1 and TrzCz2 emitters showed maximum photoluminescence emission bands at l = 443 and 433 nm, which were blueshifted relative to those of the corresponding TADF emittersw ith the same donora nd acceptor,r espectively.I nt he device application, the TrzCz1 emitter showedamaximum externalquantum efficiency of 22.4 %, with ac olor coordinate of (0.16, 0.21), and the TrzCz2 emitter showedamaximum externalquantum efficiency of 9.9 %, with ac olor coordinateo f( 0.14, 0.09). This work proved that the design strategy of decorating phenylcarbazole with ad onor and an acceptori se ffective at blueshifting the emission of TADF emitters.

Solution-processed colored electrodes for ITO-free blue phosphorescent organic light-emitting diodes

“…Both the reference ITO-and doped-PEDOT:PSS-based devices exhibited EL peaks below 470 nm whereas the EL spectrum of the PhOLED with a pristine polymer anode slightly shifted to a lower-energy region compared to the two aforementioned devices. The corresponding EL peak wavelengths of the three PhOLEDs were 469, 468, and 470, which match the color coordinates of (0.16, 0.21), (0.16, 0.16), and (0.16, 0.23), respectively [29,30,41].…”

“…Achieving a stable and deep-blue light in the current OLEDs, especially those based on phosphorescent emitters, is quite challenging due to the rare stability of the blue emitters [26][27][28][29][30]. Nevertheless, blue color is important for the realization of full-color display and lighting technologies [30].…”

Structural Design of Blue‐to‐Red Thermally‐Activated Delayed Fluorescence Molecules by Adjusting the Strength between Donor and Acceptor

“…(Figure 3). [39] The molecular configuration is distorted because of the bulky structure of 9-phenylcarbazole, thereby the molecule conjugation is destroyed. Moreover, the acceptor strength also can be decreased by sharing electrons.…”

C1-, C2-, and C3-Modified Carbazole Derivatives as Promising Host Materials for Phosphorescent Organic Light-Emitting Diodes

“…Inspired by the previously described discussions and with our continuous interest in exploring the novel functionalization methods of carbazole, , we developed two new bipolar host materials named 13CzCzCN and 13CzCNCzCN by modifying the carbazole building block at the C1 and C3 positions with a carbazole/cyanocarbazole donor and that at the C2 position with a cyano acceptor. Both of the compounds showed a high triplet energy of >2.72 eV and excellent thermal stability ( T 5d > 390 °C and T g > 207 °C).…”