Polyoxometalate‐Based MOF as a Highly Sensitive and Stable X‐ray Detector for Imaging

Abstract Polyoxometalate‐based metal–organic frameworks (POMOFs) show potential application prospects in the field of X‐ray detection in recent years. However, it is still unclear how to effectively separate X‐ray‐induced charge carriers through the effective connection between polyoxometalates (POMs) and metal–organic frameworks (MOFs) due to their current infancy research status. Here, we designed and fabricated a novel POMOF BW 12 ‐Cu II ‐MOF‐based X‐ray detector for stable and sensitive X‐ray detection and imaging. The Cu─O coordination bonds between [BW 12 O 40 ] 5− and [Cu(2,2′‐bipy) 2 ] 2+ in the structure of BW 12 ‐Cu II ‐MOF are not only conducive to charge transfer between anion and cation, resulting in a high hole carrier mobility (μ h ) of 4.80 cm 2 V −1 s −1 , but also effectively reduce ion migration and dark current simultaneously, which causes a small dark current drift as low as 1.2 × 10 −18 A cm −1 V −1 s −1 . Finally, the fabricated BW 12 ‐Cu II ‐MOF wafer device shows excellent X‐ray detection performances, yielding a high sensitivity of 9832 µC Gy air −1 cm −2 with the lowest detectable dose rate of 120 nGy air s −1 at an electric field of 200 V mm −1 under 80 kV X‐ray irradiation. Furthermore, the constructed POMOF BW 12 ‐Cu II ‐MOF as a potential candidate for X‐ray detection also exhibits good X‐ray imaging capability and long‐term operational stability without any encapsulation exposed to the air for 6 months.