Volume 137, Issue 8 e202420417
Forschungsartikel

Rational Molecular Design for Balanced Locally Excited and Charge- Transfer Nature for Two-Photon Absorption Phenomenon and Highly Efficient TADF-Based OLEDs

Gomathi Vinayakam Mageswari

Gomathi Vinayakam Mageswari

Center for Organic Photonics and Electronics Research (OPERA) and Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395 Japan

Contribution: Formal analysis (lead), Methodology (lead), Writing - original draft (lead)

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Prof. Youhei Chitose

Corresponding Author

Prof. Youhei Chitose

Center for Organic Photonics and Electronics Research (OPERA) and Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395 Japan

Department of Applied Chemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, Fukuoka, 819-0395 Japan

Contribution: Conceptualization (equal), Supervision (equal), Validation (supporting), Writing - review & editing (supporting)

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Prof. Youichi Tsuchiya

Prof. Youichi Tsuchiya

Center for Organic Photonics and Electronics Research (OPERA) and Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395 Japan

Contribution: Supervision (supporting)

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Prof. Ja-Hon Lin

Prof. Ja-Hon Lin

Department of Electro-Optical Engineering, Advanced Nanophotonics Technology Laboratory, National Taipei University of Technology, Taipei, 10608 Taiwan

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Prof. Chihaya Adachi

Corresponding Author

Prof. Chihaya Adachi

Center for Organic Photonics and Electronics Research (OPERA) and Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395 Japan

International Institute for Carbon Neutral Energy Research (I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395 Japan

Contribution: Supervision (lead), Writing - review & editing (equal)

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First published: 25 November 2024
Citations: 3

Abstract

The pursuit of highly efficient thermally activated delayed fluorescence (TADF) emitters with two-photon absorption (2PA) character is hampered by the concurrent achievement of a small singlet-triplet energy gap (ΔEST) and high photoluminescence quantum yield (ΦPL). Here, by introducing a terephthalonitrile unit into a sterically crowded donor-π-donor structure, inducing a hybrid electronic excitation character, we designed unique TADF emitters possessing 2PA ability. This rational molecular design was achieved through a main π-conjugated donor-acceptor-donor backbone in line with locally excited feature renders a large oscillator strength and transition dipole moment, maintaining a high 2PA cross-section value. The ancillary N-donor-acceptor-donor with charge transfer character highly balances the TADF phenomenon by minimizing ΔEST. A near-unity ΦPL value with a large radiative decay rate over an order of magnitude higher than the intersystem crossing rate and a high horizontal orientation ratio of 0.95 were simultaneously attained for TPCz2NP. The organic light-emitting diodes fabricated with this material exhibit a high maximum external quantum efficiency of 25.4 % with an elevated 2PA cross-section (σ2) value up to 143 GM at 850 nm. These findings offer a venue for designing high-performance TADF emitters with exceptional performance inclusive of 2PA properties, expanding for future functional material design.

Conflict of Interests

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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