Sky-Blue Thermally Activated Delayed Fluorescence with Intramolecular Spatial Charge Transfer Based on a Dibenzothiophene Sulfone Emitter

Abstract

Intramolecular spatial charge transfer (ISCT) plays a critical role in determining the optical and charge transport properties of thermally activated delayed fluorescence (TADF) materials. Herein, a new donor/acceptor-type TADF compound based on rigid dibenzothiophene sulfone (DBTS) moiety, STF-DBTS, was designed and synthesized. Fluorene unit was used as a rigid linker to position the rigid acceptor and donor subunit in close vicinity with control over their spacing and molecular structure and to achieve high photoluminescence quantum yield (∼53%) and TADF property. For comparison purposes, we constructed the more flexible STF-DPS with a less rotationally constrained diphenylsulphone (DPS) acceptor instead of the rigid DBTS units, and STF-DPS showed no TADF properties and lower PLQY (16.0%). Organic light-emitting diodes (OLEDs) based on STF-DBTS achieve an external quantum efficiency (EQE) of 10.3% at 488 nm, which is a fivefold improvement in EQE with respect to STF-DPS.

Harvesting triplet excitons for near-infrared electroluminescence via thermally activated delayed fluorescence channel

“…Considering the low fluorescence efficiency governed by the energy gap law, there is a large amount of energy in NIR TADF emitters converting to thermal energy, which could also be used for photothermal therapy (Alifu et al, 2018). On the other hand, the small DE ST caused for delayed fluorescence could also generate singlet oxygen, which could be used for anticancer therapy (Yang et al, 2020b). Moreover, NIR TADF emitters could also be applied for chemical sensors due to large conjugation (He et al, 2019).…”

Chiral Spiro‐Axis Induced Blue Thermally Activated Delayed Fluorescence Material for Efficient Circularly Polarized OLEDs with Low Efficiency Roll‐Off

“…However, spiro‐type TADF molecules containing through space charge transfer (TSCT) process [13] normally suffer from obvious device efficiency roll‐off. Quite recently, great progresses have been made by Jiang and Liao's group [10b, 13a,d–f] . Via a parallel surface strategy, TSCT process is successfully enhanced and some devices exhibit EQE max over 20 % with low efficiency roll‐off [10b, 13a,e,f,i] .…”

Organosulfur Materials with High Photo- and Photo-Oxidation Stability: 10-Anthryl Sulfoxides and Sulfones and Their Photophysical Properties Dependent on the Sulfur Oxidation State

“…The electronic devices with the sulfone-based materials can be expected to have: (1) an efficient electron-injection and transport, an improved balance of holes and electrons allowing their effective recombination in emissive layers; (2) a high triplet energy for the efficient blue phosphorescent organic light-emitting diodes; (3) wide band gaps; and (4) good electrochemical and thermal stabilities [2,5,31]. To date, the sulfone-based materials have also been used as host or emitting materials in phosphorescent organic light-emitting diodes (PhOLEDs) and efficient, thermally activated delayed fluorescence (TADF) emitting materials [1][2][3][4][5][6][7][8].…”