Highly Efficient, Low‐Dose, and Ultrafast Carbazole X‐Ray Scintillators

Abstract Organic fluorescence scintillators, owing to the ultrafast response time, versatile chemical structures, low processing temperature, and low cost, are considered as one of the promising materials for medical diagnostics, radiation detection, and X‐ray astronomy. However, the low radioluminescence (RL) intensity and low sensitivity hinder their practical applications. In this work, a highly efficient organic fluorescent scintillator, 4,4′‐bis(9‐carbazolyl)biphenyl (CBP), is presented, exhibiting a high X‐ray RL intensity, narrow full width at half‐maximum of 49 nm, and ultrafast decay time of 1.15 ns. More importantly, it has a low detection limit of 25.5 nGy s −1 , which is only 1/215 dose rate compared with the commercial X‐ray diagnostics. Such an excellent scintillation performance is mainly attributed to its high photoluminescence quantum yield (PLQY = 61.92%) and good carrier transport (average hole mobility of 0.094 cm 2 V −1 s −1 ). By mixing the CBP into polydimethylsiloxane, the fabricated large area flexible film can be applied in X‐ray radiography, which exhibits a high spatial resolution of 14.3 lp mm −1 at MTF > 0.2. This work paves a way for the implementation of organic fluorescence dyes with high PLQY, high carrier mobility in efficient X‐ray scintillation and imaging.