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Heavy-atom engineering of thermally activated delayed fluorophores for high-performance X-ray imaging scintillators

Nature Photonics volume 16, pages 869–875 (2022)Cite this article

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Abstract

The architectural design and fabrication of low-cost and reliable organic X-ray imaging scintillators with high light yield, ultralow detection limits and excellent imaging resolution is becoming one of the most attractive research directions for chemists, materials scientists, physicists and engineers due to the devices’ promising scientific and applied technological implications. However, the optimal balance among X-ray absorption capability, exciton utilization efficiency and photoluminescence quantum yield of organic scintillation materials is extremely difficult to achieve because of several competitive non-radiative processes, including intersystem crossing and internal conversion. Here we introduced heavy atoms (Cl, Br and I) into thermally activated delayed fluorescence (TADF) chromophores to significantly increase their X-ray absorption cross-section and maintaining their unique TADF properties and high photoluminescence quantum yield. The X-ray imaging screens fabricated using TADF-Br chromophores exhibited highly improved X-ray sensitivity and imaging resolution compared with the TADF-H counterpart. More importantly, the high X-ray imaging resolution of >18.0 line pairs per millimetre achieved from the TADF-Br screen exceeds most reported organic and conventional inorganic scintillators. This study could help revive research on organic X-ray imaging scintillators and pave the way towards exciting applications for radiology and security screening.

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Fig. 1: Illustration of the heavy-atom engineering strategy on the enhancement of X-ray sensitivity of TADF chromophores.
Fig. 2: Characterization of optical properties of TADF films.
Fig. 3: DFT calculations and TA spectroscopy measurements.
Fig. 4: RL and X-ray imaging applications.

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Data availability

The main data supporting the findings of this study are available within this Article and its Supplementary Information. Further data are available from the corresponding author on reasonable request. Source data are provided with this paper.

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Acknowledgements

This work was supported by the King Abdullah University of Science and Technology (KAUST).

Author information

Author notes

  1. These authors contributed equally: Jian-Xin Wang, Luis Gutiérrez-Arzaluz, Xiaojia Wang.

Authors and Affiliations

  1. Advanced Membranes and Porous Materials Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia

    Jian-Xin Wang, Luis Gutiérrez-Arzaluz, Tengyue He, Mohamed Eddaoudi & Omar F. Mohammed

  2. KAUST Catalysis Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia

    Luis Gutiérrez-Arzaluz & Osman M. Bakr

  3. Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan, China

    Xiaojia Wang & Yuhai Zhang

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  1. Jian-Xin Wang
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Contributions

J.-X.W. and O.F.M. conceived the project. J.-X.W. synthesized the TADF chromophores, prepared the films for measurements and applications, performed the steady-state experiments and some time-resolved experiments, and analysed the data. L.G.A. performed the TA and TCSPC measurements as well as the DFT calculations. J.-X.W., X.W. and Y.Z. performed and analysed the scintillation measurements. T.H. synthesized the CsPbBr3 nanosheet. O.M.B and M.E. contributed to the discussion of the experimental data and provided valuable suggestions. O.F.M. supervised the project and suggested the analysis of the experimental data. J.-X.W. and O.F.M. co-wrote the manuscript.

Corresponding author

Correspondence to Omar F. Mohammed.

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Competing interests

O.M.B. is a founder of Quantum Solutions, a company that develops optoelectronic devices. The other authors declare no competing interests.

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Nature Photonics thanks Kris Iniewski and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–8, Tables 1–4 and material synthesis.

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Wang, JX., Gutiérrez-Arzaluz, L., Wang, X. et al. Heavy-atom engineering of thermally activated delayed fluorophores for high-performance X-ray imaging scintillators. Nat. Photon. 16, 869–875 (2022). https://doi.org/10.1038/s41566-022-01092-x

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