Efficient organic X-ray scintillators achieved by hybridized local and charge-transfer emitters with through-space heavy atom-π interactions

The design and fabrication of organic X-ray imaging scintillators with large Stokes shift, narrow-band, fast, and efficient radioluminescence becomes an attractive research direction in many fields, such as medical diagnostics, scientific instruments and high-energy physics. However, the trade-off between these diverse scintillation properties is an enormous challenge facing almost all scintillators. To overcome this limitation, in this work, we developed a strategy based on through-space heavy atom-π interactions to improve the performance of organic scintillators by introducing alkyl bromides into hybridized local and charge transfer (HLCT) emitters. Specifically, the HLCT state's locally excited characters result in a short radiative lifetime (3.74 ns) and a narrow radioluminescence bandwidth (56 nm). The HLCT state's charge-transfer features yield a large Stokes shift (> 100 nm). Meanwhile, through-space bromine-π interactions enhance the photoluminescence quantum yield to 100%. Notably, a high X-ray imaging resolution (> 40.0 lp mm−1) was achieved, making the highest spatial resolution for organic scintillators reported to date. This work provides a method to design scintillators with excellent comprehensive performances and paves the way towards promising applications for high-resolution X-ray imaging.