Identity of T* matters! improved krisc by modulating locally excited triplet state in TADF emitters

Madalasa Mondal; Ratheesh K. Vijayaraghavan

doi:10.1117/12.3017337

19 June 2024 Identity of T* matters! improved k_riscby modulating locally excited triplet state in TADF emitters

Madalasa Mondal, Ratheesh K. Vijayaraghavan

Proceedings Volume PC13013, Organic Electronics and Photonics: Fundamentals and Devices IV; PC1301309 (2024) https://doi.org/10.1117/12.3017337
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

We have presented findings on TADF emitters consisting of a strong D-A structure, exhibiting hybridized electronic excited states that encompass a primary donor-to-acceptor long-range (LR) interaction and an ancillary short-range (SR) charge-transfer characteristic. This configuration successfully balances a small ΔEST and a large f value. Our thorough theoretical and experimental analysis has uncovered that the addition of peripheral donor units to the core D-A backbone leads to the formation of multiple triplet excited states between the S1 and T1 states, exhibiting locally excited or hybridized characteristics. The close alignment of the 1CT and 3LE states accelerates the spin-flip process, resulting in a sizable radiative rate nearly equivalent to the intersystem crossing (ISC) rate. Additionally, a decent reverse ISC rate (107 s-1) is simultaneously obtained in one emitter, leading to a short (ns) delayed lifetime and effectively suppressing efficiency roll-off.

Conference Presentation

Citation Download Citation

Madalasa Mondal and Ratheesh K. Vijayaraghavan "Identity of T* matters! improved k_riscby modulating locally excited triplet state in TADF emitters", Proc. SPIE PC13013, Organic Electronics and Photonics: Fundamentals and Devices IV, PC1301309 (19 June 2024); https://doi.org/10.1117/12.3017337

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