Sulfone‐Embedded Heterocyclic Narrowband Emitters with Strengthened Molecular Rigidity and Suppressed High‐Frequency Vibronic Coupling

Abstract

Sulfone-embedded heterocyclics are of great interest in organic light-emitting diodes (OLEDs), however, exploring highly efficient narrowband emitters based on sulfone-embedded heterocyclics remains challenging. Herein, five emitters with different sulfur valence state and molecular rigidity, namely tP, tCPD, 2tCPD, tPD and tPT, are thoroughly analysed. With restricted twisting of flexible peripheral phenyl by strengthening molecular rigidity, molecular emission spectra can be enormously narrowed. Further, introducing the sulfone group with bending vibration in lowfrequency region that suppresses high-frequency vibration, sharp narrow full-widths at half-maximum of 28 and 25 nm are achieved for 2tCPD and tPD, respectively. Maximum external quantum efficiencies of 22.0 % and 27.1 % are successfully realized for 2tCPDand tPD-based OLED devices. These results offer a novel design strategy for constructing narrowband emitters by introducing sulfone group into a rigid molecular framework.

Realizing highly efficient deep-blue organic light-emitting diodes towards Rec.2020 chromaticity by restricting the vibration of the molecular framework

“…The results indicated that the l total of BOC-PSi is slightly smaller than that of BOC-PC (0.20 vs. 0.30 eV, vide Fig. 1d), implying that BOC-PSi possesses superior molecular skeleton rigidity to BOC-PC, 21,22 while the l total of BOC is only 0.17 eV, indicative of its excellent rigidity (Fig. S14 †).…”