Organic phosphors with bright triplet excitons for efficient X-ray-excited luminescence

Materials that exhibit X-ray-excited luminescence have great potential in radiation detection, security inspection, biomedical applications and X-ray astronomy^1–5. However, high-performance materials are almost exclusively limited to ceramic scintillators, which are typically prepared under high temperatures⁶. Herein we report metal-free organic phosphors based on a molecular design that supports efficient triplet exciton harvesting to enhance radioluminescence. These organic scintillators exhibit a detection limit of 33 nGy s^–1, which is 167 times lower than the standard dosage for X-ray medical examination and we demonstrate their potential application in X-ray radiography. These findings provide a fundamental design principle and new route for the creation of promising alternatives to incumbent inorganic scintillators. Furthermore, they offer new opportunities for development of flexible, stretchable X-ray detectors and imagers for non-destructive radiography testing and medical imaging.