Efficient X-ray Detection of Polyoxometalates@Metal–Organic Frameworks Based on Host–Guest Electron Transfer

Abstract

Semiconductive metal−organic frameworks (MOFs) have attracted conspicuous interest in X-ray detection. The host−guest strategy has been proven to be an effective means to improve the performance of MOF-based semiconductors. However, introducing a novel guest that combines carriers' regulating ability and X-ray absorption enhancement has not been explored. Herein, two polyoxometalates (POMs) with electronrich and element-heavy are introduced into MOFs to architect host−guest structures applied for X-ray detection. Two POMs@ MOFs (1 and 2) both can convert X-ray photons to recordable electrical signals. Detector 1 shows a high photocurrent profiting from its stronger exciton dissociation dynamic, therefore exhibiting a high sensitivity of 73.98 μC Gy −1 cm −2 . With the high quality of [PW 12 O 403− ], detector 2 shows an ultrahigh X-ray absorption, resulting in high on/off ratio and low detection limit. Moreover, the electron transfer mechanism from POMs to Cu(II) is substantiated by using spectroscopy and theoretical calculations.