First N-Borylated Emitters Displaying Highly Efficient Thermally Activated Delayed Fluorescence and High-Performance OLEDs

Abstract

Despite the fast boom of thermally activated delayed fluorescence (TADF) emitters bearing borane-based acceptor, so far, no TADF emitter with a direct B-N linkage between N-donor and boryl acceptor has been reported. The latter should simplify the molecular architecture and hence facilitate the synthetic design and versatility. We report here the preparation and characterization of a new series of N-borylated compounds with functional acridine donor unit; namely: ACBM, PACBM, and SACBM. Spectroscopic studies were performed to explore their photophysical properties that exhibited prominent solvatochromism and thermally activated delayed fluorescence. The time-dependent DFT calculation indicated the involvement of substantial intramolecular charge transfer character for which HOMO and LUMO are spatially separated. For compound SACBM, fabrication of green emitting OLED gave CIE chromaticity of (0.22, 0.59) and maximum external quantum efficiency, luminance efficiency and power efficiency of 19.1%, 60.9 cd/A, and 43.6 lm/W, respectively, demonstrating for the first time the highly efficient OLEDs using N-borylated TADF emitters.

Electron‐Rich Twistacene‐Modified Arylboron Donor–Acceptor Systems: Synthesis, Photophysics, and Electroluminescence with Hot Exciton Response

“…Therefore, this π‐system could be considered as an electron‐rich group or “electron reservoir”. If this molecule is linked with the proper acceptor, the as‐formed D‐A compounds might exhibit TADF character …”

Catalyst‐ and Template‐Free Ultrafast Visible‐Light‐Triggered Dimerization of Vinylpyridine‐Functionalized Tetraarylaminoborane: Intriguing Deep‐Blue Delayed Fluorescence

“…[8] Ac ontinuing challenge in organic optoelectronic technology research is the design and development of stable luminescent materials that can effectively harvest both singlet and triplet excitons.I nt he present decade,alot of research effort has been devoted to the development of delayed fluorescence (DF) materials,since the devices fabricated with DF materials show improved efficiency over phosphor-doped devices. [10][11][12][13][14][15][16][17] Recently,boron has found arole in the emerging field of TADF materials (representative examples are shown in Chart S1 in the Supporting Information). [9,18] By exploiting its inherent Lewis acidity, boron-containing compounds are being widely exploited in numerous fields.…”

“…[9,18] Molecules with donor-acceptor (D-A) architectures have proven particularly well suited for the construction of DF systems. [12,14] Very recently,D -A systems with BN units in the backbone have received considerable attention owing to their unique optoelectronic properties. [10][11][12][13][14][15][16][17] Recently,boron has found arole in the emerging field of TADF materials (representative examples are shown in Chart S1 in the Supporting Information).…”

“…[9,18] By exploiting its inherent Lewis acidity, boron-containing compounds are being widely exploited in numerous fields. [13][14][15][16] Fore xample,C hi et al demonstrated DF characteristics of aminoboranes by accessing the lower-energy triplet state of the BN fragment. [12,14] Very recently,D -A systems with BN units in the backbone have received considerable attention owing to their unique optoelectronic properties.…”

“…[10][11][12][13][14][15][16][17] Recently,boron has found arole in the emerging field of TADF materials (representative examples are shown in Chart S1 in the Supporting Information). [14] Our group has al ongstanding interest in the design and development of new solid-state emitters. [13][14][15][16] Fore xample,C hi et al demonstrated DF characteristics of aminoboranes by accessing the lower-energy triplet state of the BN fragment.…”