Organic molecules with dual triplet-harvesting channels enable efficient X-ray scintillation and imaging

Organic scintillators have recently gained considerable attentions in X-ray detection for their potential applications in biomedical radiograph and security inspection. However, the weak X-ray absorption and/or inefficient exciton utilization have limited the development and commercialization of organic scintillators. Currently, high-performance X-ray organic scintillators are scarce and organic scintillators with dual triplet-harvesting channels have not been explored before. Here, we develop several proof-of-concept sulfone-based organic molecules, C1-C7, using different alkoxy chains to manipulate molecular packing mode. These materials exhibit dual triplet-harvesting channels of thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) in aggregated state. Inspiringly, these molecules display distinct radioluminescence under the X-ray stimulation. Among them, C6 behaves the highest light yield of 16,558 photons MeV-1. Moreover, clear X-ray images are demonstrated in both aggregated state and single-molecule level. High spatial resolutions of 15.0 and 10.6 line pairs per millimeter (lp mm-1) are achieved for rigid and flexible scintillator screens, exceeding most reported organic and conventional inorganic scintillators. These results highlight the great potential of organic molecules with TADF and RTP nature for efficient X-ray scintillation and imaging. A series of organic scintillators are designed and synthesized to exhibit both TADF and RTP features in the aggregated state. These materials possessing dual triplet exciton-harvesting channels demonstrate clear X-ray imaging in both single-molecule level and aggregated state, accompanied by a high spatial resolution of 15.0 lp mm-1.image