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Tuning of the Singlet–Triplet Energy Gap of Donor-Linker-Acceptor Based Thermally Activated Delayed Fluorescent Emitters

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Abstract

Thermally activated delayed fluorescent emitters based on carbazole donor, benzonitrile acceptor with the linkers biphenyl, bipyridine and naphthalene are investigated using the density functional theoretical method. The molecule in which bipyridine acts as the linker with the least ΔEST is further selected for the designing of a series of D-L-A framework TADF molecules. Remarkably, the ΔEST is decreased successively by attaching the additional cyano groups at the acceptor site which is further reduced when the electron donating methoxy groups are attached at the donor site. To know the effect of substituents on ΔEST, the acceptor moiety of the D-L-A framework is modified with -F, -Cl and -CF3 substituents. The studies showed a relatively less decrement in the value of ΔEST compared to the cyano substituted molecules. However, ΔEST significantly reduced further on attaching methoxy groups at the donor site.

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The coordinates of the optimized geometries are available on request.

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Acknowledgements

Paras acknowledges Council of Scientific and Industrial Research (CSIR), New Delhi for the fellowship. CNR is grateful to the Scientific and Engineering Research Board (SERB) for the Research Grant EMR/2016/008024. The authors acknowledge Indian Institute Technology Roorkee for the infrastructure.

Funding

CNR is grateful to the Scientific and Engineering Research Board (SERB) for the Research Grant EMR/2016/008024.

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  1. Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India, 247667

    Paras & C. N. Ramachandran

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  1. Paras
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CNR conceived the investigation. Paras performed the calculations. Both authors analyzed the results and wrote the manuscript.

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Correspondence to C. N. Ramachandran.

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Paras, Ramachandran, C.N. Tuning of the Singlet–Triplet Energy Gap of Donor-Linker-Acceptor Based Thermally Activated Delayed Fluorescent Emitters. J Fluoresc 34, 1343–1351 (2024). https://doi.org/10.1007/s10895-023-03365-2

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