Issue 43, 2022

Efficient deep red/near-infrared thermally activated delayed fluorescence emitters via molecular reconstruction: theoretical insights

Abstract

Thermally activated delayed fluorescence (TADF) molecules with deep-red (DR) and near-infrared (NIR) luminescence show great potential in biomedical sensing/imaging and telecommunications. However, developing efficient DR- and NIR-TADF molecules remains a powerful challenge, and new design strategies are highly desired. Based on 2,3-bis(4-(diphenylamino)phenyl)quinoxaline-5,8-dicarbonitrile (CNQ-TPA), two novel TADF molecules CNQ-b-TPA and CNQ-f-TPA are theoretically constructed through the design strategy of molecular bonding and molecular fusion. The photophysical properties and luminescence mechanisms of the three molecules in toluene and the crystal state are revealed with first-principles calculations and the thermal vibration correlation function (TVCF) method. Compared with CNQ-TPA, CNQ-b-TPA and CNQ-f-TPA can achieve an effective red-shift of intrinsic emission and efficient DR and NIR emission. Remarkably, molecular bonding and molecular fusion not only greatly increase the oscillator strength, but also effectively reduce the energy gap between the first singlet excited state (S1) and the first triplet excited state (T1), resulting in their high radiative and reverse intersystem crossing rate. Moreover, the charge transport properties are studied based on kinetic Monte Carlo simulations. Molecular bonding to balance charge transport is found, enabling ambipolar transport properties. Our work provides a feasible solution to overcome the design limitations of previous DR- and NIR-TADF materials and predicts good candidates for both DR- and NIR-TADF emitters.

Graphical abstract: Efficient deep red/near-infrared thermally activated delayed fluorescence emitters via molecular reconstruction: theoretical insights

Supplementary files

Article information

Article type
Paper
Submitted
11 Aug 2022
Accepted
13 Oct 2022
First published
13 Oct 2022

Phys. Chem. Chem. Phys., 2022,24, 26764-26775

Efficient deep red/near-infrared thermally activated delayed fluorescence emitters via molecular reconstruction: theoretical insights

K. Zhang, L. Cai, J. Fan, Y. Song, L. Lin and C. Wang, Phys. Chem. Chem. Phys., 2022, 24, 26764 DOI: 10.1039/D2CP03697E

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