The scintillation behavior of organic molecules under X-ray irradiation was discovered on anthracene crystals as early as 1947, long before the discovery of organic electronics. In recent years, researchers have made significant progress in enhancing the radio-luminescence intensity of organic scintillators by introducing heavy atom elements and thermally activated delayed fluorescence (TADF) properties. However, the light yield (LY) of the vast majority of organic scintillators is still far lower than that of inorganic scintillators, and this gap remains a key issue that needs to be urgently addressed in this field.
In this work, researchers introduced a highly stable charge-separated (CS) state trap in the design of organic scintillators based on the donor-acceptor (D-A) doping strategy. By taking advantage of the unique thermally activated delayed phosphorescence (TADP) mechanism induced by the CS state trap, the efficient capture and energy conversion of high-energy carriers have been successfully achieved.
The radiation luminescence intensity of the organic scintillator designed and synthesized in this study is significantly superior to that of most traditional commercial inorganic scintillators, with a relative LY that can reach 65,535 photons MeV -1 . It is particularly worth noting that this organic scintillator can be observed by the naked eye to emit a super-long afterglow for 7 hours after the X-ray excitation stops. This is the first time that a super-long afterglow emission has been observed in organic small molecules under X-ray excitation.
The X-ray afterglow imaging technology developed based on the flexible scintillation film prepared from this organic scintillator can effectively observe the internal structural defects of the bottle and the fine scratches on the inner metal layer of metal-plastic composite pipes. This breakthrough technology provides a new non-destructive testing method for the identification of cultural relics and Industrial radiographic testing.
National Science Review