Open-shell TADF: Quartet-derived luminescence with dark radicals
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arXiv
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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
| Published: |
2024
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| _version_ | 1866913884172976128 |
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| author | Gorgon, Sebastian Murto, Petri Congrave, Daniel G. Matasovic, Lujo Bond, Andrew D. Myers, William K. Bronstein, Hugo Friend, Richard H. |
| author_facet | Gorgon, Sebastian Murto, Petri Congrave, Daniel G. Matasovic, Lujo Bond, Andrew D. Myers, William K. Bronstein, Hugo Friend, Richard H. |
| contents | High-spin states in organic molecules offer promising tuneability for quantum technologies. Photogenerated quartet excitons are an extensively studied platform, but their applications are limited by the absence of optical read-out via luminescence. Here we demonstrate a new class of synthetically accessible molecules with quartet-derived luminescence, formed by appending a non-luminescent TEMPO radical to Thermally Activated Delayed Fluorescence (TADF) chromophores previously used in OLEDs. The low singlet-triplet energy gap of the chromophore opens a luminescence channel from radical-triplet coupled states. We establish a set of design rules by tuning the energetics in a series of compounds based on a naphthalimide (NAI) core. We observe generation of quartet states and measure the strength of radical-triplet exchange (0.7 GHz). In DMAC-TEMPO, up to 72% of detected photons emerge after reverse intersystem crossing from the quartet state repopulates the state with singlet character. This design strategy does not rely on a luminescent radical to provide an emission pathway from the high-spin state. The large library of TADF chromophores promises a greater pallet of achievable emission colours. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_18112 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Open-shell TADF: Quartet-derived luminescence with dark radicals Gorgon, Sebastian Murto, Petri Congrave, Daniel G. Matasovic, Lujo Bond, Andrew D. Myers, William K. Bronstein, Hugo Friend, Richard H. Materials Science Chemical Physics Optics High-spin states in organic molecules offer promising tuneability for quantum technologies. Photogenerated quartet excitons are an extensively studied platform, but their applications are limited by the absence of optical read-out via luminescence. Here we demonstrate a new class of synthetically accessible molecules with quartet-derived luminescence, formed by appending a non-luminescent TEMPO radical to Thermally Activated Delayed Fluorescence (TADF) chromophores previously used in OLEDs. The low singlet-triplet energy gap of the chromophore opens a luminescence channel from radical-triplet coupled states. We establish a set of design rules by tuning the energetics in a series of compounds based on a naphthalimide (NAI) core. We observe generation of quartet states and measure the strength of radical-triplet exchange (0.7 GHz). In DMAC-TEMPO, up to 72% of detected photons emerge after reverse intersystem crossing from the quartet state repopulates the state with singlet character. This design strategy does not rely on a luminescent radical to provide an emission pathway from the high-spin state. The large library of TADF chromophores promises a greater pallet of achievable emission colours. |
| title | Open-shell TADF: Quartet-derived luminescence with dark radicals |
| topic | Materials Science Chemical Physics Optics |
| url | https://arxiv.org/abs/2411.18112 |