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.

Sensing Mechanism and Excited-State Dynamics of a Widely Used Intracellular Fluorescent pH Probe: pHrodo

“…The calculated RMSD between S 1 and S 0 of pHrodoH is only 0.46 Å, which is only one-third of the calculated RMSD of pHrodo (Table S1). Meanwhile, due to the distribution of small FMOs on arylpyrylium, the free rotation of arylpyrylium plays a smaller role in molecular emission and cannot lead to a fast nonradiation process like that in pHrodo . Combined with the enlarged oscillator strength, the significant improvement in FQY for pHrodoH could be expected, which agrees with the measured FQY of pHrodoH being ∼40%.…”

A Quadruple‐Borylated Multiple‐Resonance Emitter with para/meta Heteroatomic Patterns for Narrowband Orange‐Red Emission

“…Such a distribution is in line with the bonding characteristics and is favorable for narrowing the energy gap [16] . However, it also inevitably enhances the vibrational interaction between the S 0 and S 1 states as well as the vibrational relaxation in the S 1 state, which is undesirable for narrowband emission [17] . For part F2 ( para B‐π‐N pattern), a typical MR‐featured atom‐located distribution of FMOs is realized; specifically, the HOMO and LUMO alternately disperse on adjacent C atoms or corresponding N/B atoms.…”

“…[16] However, it also inevitably enhances the vibrational interaction between the S 0 and S 1 states as well as the vibrational relaxation in the S 1 state, which is undesirable for narrowband emission. [17] For part F2 (para B-π-N pattern), a typical MR-featured atomlocated distribution of FMOs is realized; specifically, the HOMO and LUMO alternately disperse on adjacent C atoms or corresponding N/B atoms. According to the literature, such nonbonding characteristics can minimize the vibronic coupling between the S 0 and S 1 states as well as vibrational relaxation in the S 1 state, allowing the realization of an extremely narrow photoluminescence (PL) band.…”

Facile Functionalization of Ambipolar, Nitrogen-Doped PAHs toward Highly Efficient TADF OLED Emitters

“…π-Conjugated polycyclic aromatic hydrocarbons (PAHs) − comprising precisely arranged heteroatoms have recently caused a growing interest due to their prospective application in organic electronics. In this context, much attention has been paid to PAH architectures bearing nitrogen atom(s) positioned at the central part (hub position) of aromatic scaffolds (N-PAHs). − The synthetic integration of an N-dopant within three rings (varying from pentagons to heptagons) is anticipated to not only produce a steric constraint that would largely influence the geometry and stability of N-doped PAHs but primarily to affect energy, localization, and spatial extent of a molecular orbital (HOMO) energy level, leading to their strong electron-rich character. , The latter features constitute the development of an innovative class of semiconducting materials that have found utility as organic field effect transistors, sensing, p-type transporting layers in perovskite solar cells, and importantly thermally activated delayed fluorescence (TADF) for organic light-emitting diodes (OLEDs). In this regard, researchers demonstrated nitrogen-embedded PAHs as eligible to cause the multiple resonance (MR) effect in which MOs are alternately distributed likewise to the chess board triggering a short-range charge-transfer (CT) TADF emission.…”