scholarly journals D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

2018 ◽  
Vol 14 ◽  
pp. 672-681 ◽  
Author(s):  
Lin Gan ◽  
Xianglong Li ◽  
Xinyi Cai ◽  
Kunkun Liu ◽  
Wei Li ◽  
...  
Keyword(s):  
Internal Conversion ◽  
Delayed Fluorescence ◽  
Structure Property ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Structure Property Relationship ◽  
Fluorescent Materials ◽  
Donor Acceptor ◽  
Splitting Energy

The design of orange-light emitting, thermally activated, delayed fluorescence (TADF) materials is necessary and important for the development and application of organic light-emitting diodes (OLEDs). Herein, two donor–acceptor–donor (D–A–D)-type orange TADF materials based on fluorenone and acridine, namely 2,7-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (27DACRFT, 1) and 3,6-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (36DACRFT, 2), were successfully synthetized and characterized. The studies on their structure–property relationship show that the different configurations have a serious effect on the photoluminescence and electroluminescence performance according to the change in singlet–triplet splitting energy (ΔE ST) and excited state geometry. This indicates that a better configuration design can reduce internal conversion and improve triplet exciton utilization of TADF materials. Importantly, OLEDs based on 2 exhibited a maximum external quantum efficiency of 8.9%, which is higher than the theoretical efficiency of the OLEDs based on conventional fluorescent materials.

Structure-Property Relationship Study of Blue Thermally Activated Delayed Fluorescence Molecules with Different donor and position substitutions: Theoretical Perspective and Molecular Design

2021 ◽  
Author(s):  
Yuzhi Song ◽  
Bihe Li ◽  
Songsong Liu ◽  
Ming Qin ◽  
Yang Gao ◽  
...  
Keyword(s):  
Molecular Design ◽  
Theoretical Perspective ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Structure Property ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Structure Property Relationship ◽  
Display Resolution

Blue-efficient thermally activated delayed fluorescence emitters are widely desired in organic light emitting diodes due to their advantages in both improving display resolution and providing better pixels. However, both the...

scholarly journals Regioisomeric Effect on the Excited-State Fate Leading to Room-Temperature Phosphorescence or Thermally Activated Delayed Fluorescence in a Dibenzophenazine-Cored Donor–Acceptor–Donor System

2021 ◽  
Author(s):  
Takumi Hosono ◽  
Nicolas Oliveira Decarli ◽  
Paola Zimmermann Crocomo ◽  
Tsuyoshi Goya ◽  
Leonardo Evaristo de Sousa ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Room Temperature Phosphorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor Acceptor ◽  
Emission Behavior

Exploring design principle for switching thermally activated dealyed fluorescecne (TADF) and room temperature phosphorescence (RTP) is a fundamentally imporant research in developing triplet-mediated photofunctional organic materials. Herein systematic studies on the regioisomeric and substituents effects in a twisted donor–acceptor–donor (D–A–D) scaffold (A = dibenzo[a,j]phenazine; D = dihydrophenazasiline) on the fate of the excited state have been performed. The study revealed that the regiosiomerism clearly affects the emission behavior of the D–A–D compounds. Distinct difference in TADF, dual TADF & RTP, and dual RTP were observed, depending on the host used. Furthermore, OLED organic light-emitting diodes (OLEDs) fabricated with the developed emitters achieved high external quantum yields for RTP-based OLEDS up to 7.4%.

The Effect of Molecular Aggregation of Thermally Activated Delayed Fluorescence Sensitizer for Hyperfluorescence in Organic Light-Emitting Diodes

2021 ◽  
Author(s):  
Eun Young Park ◽  
Ji Hyun Park ◽  
Yun-Hi Kim ◽  
Min Chul Suh
Keyword(s):  
Resonance Effect ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Synthetic Material ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Phenyl Sulfone ◽  
Donor Acceptor

The exciton behavior of a new synthetic material, 11-phenyl-11H-9,16-dioxa-11-aza-4b-boraindeno[1,2-a]naphtho[3,2,1-de] anthracene (Ph-OBNA), which displays a multi-resonance effect, and bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) with a donor–acceptor-donor structure was analyzed. First, we conducted quantum mechanical...

scholarly journals Intramolecular Through-Space Charge-Transfer Emitters Featuring Thermally Activated Delayed Fluorescence for High-Efficiency Electroluminescent Devices

2021 ◽  
Author(s):  
Yongjun song ◽  
lei he ◽  
Mingxing Tian ◽  
Renyou Yu
Keyword(s):  
Charge Transfer ◽  
Space Charge ◽  
High Efficiency ◽  
Theoretical Calculations ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor Acceptor ◽  
First Time

Through-space charge-transfer (TSCT) emitters have been extensively explored for thermally activated delayed fluorescence (TADF), but arranging various donors and acceptors into rigid cofacial conformations for various efficient TSCT TADF emitters has still remained a challenge. Here we report for the first time a “fixing acceptor” design to reach various efficient TSCT TADF emitters. By chemically fixing the acceptor (benzophenone) with a rigid spiro structure and cofacially aligning various donors with the fixed acceptor, a series of efficient TSCT TADF emitters have been developed. Single-crystal structures and theoretical calculations have verified closely-packed cofacial donor/acceptor conformations and favorable TSCT in the emitters. The emitters afford sky-blue to yellow TADF emission in doped films, with high photoluminescent efficiencies of up to 0.92 and reverse intersystem crossing rates of up to 1.0×106 s−1. Organic light-emitting diodes using the emitters afford sky-blue to yellow electroluminescence with high external quantum efficiencies of up to 20.9%. The work opens a new avenue toward a wide variety of efficient TSCT TADF emitters.

scholarly journals Efficient Red Thermally Activated Delayed Fluorescence Emitters Based on a Dibenzonitrile-Substituted Dipyrido[3,2-a:2′,3′-c]phenazine Acceptor

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2427
Author(s):  
Lin He ◽  
Xuan Zeng ◽  
Weimin Ning ◽  
Ao Ying ◽  
Yunbai Luo ◽  
...  
Keyword(s):  
Transfer Characteristic ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Donor Acceptor ◽  
Molecular Rigidity ◽  
Acceptor Moiety

How to construct efficient red-emitting thermally activated delayed fluorescence (TADF) materials is a challenging task in the field of organic light-emitting diodes (OLEDs). Herein, an electron acceptor moiety, 3,6-DCNB-DPPZ, with high rigidity and strong acceptor strength was designed by introducing two cyanobenzene groups into the 3,6-positions of a dipyrido[3,2-a:2′,3′-c]phenazine unit. A red-emitting compound, 3,6_R, has been designed and synthesized by combining the rigid acceptor unit with two triphenylamine donors. Due to high molecular rigidity and strong intramolecular charge transfer characteristic in donor–acceptor–donor skeleton, 3,6_R exhibited a red emission with a high photoluminescence quantum yield of 86% and distinct TADF nature with short delayed fluorescence lifetime of about 1 microsecond. Accordingly, the OLED using 3,6_R as the guest emitter gained a high external quantum efficiency of 12.0% in the red region with an electroluminescence peak of 619 nm and favorable Commission Internationale de l’Eclairage coordinates of (0.62, 0.38).

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