Radiochromic semiconductive MOFs with high sensitivity and fast photochromic responses for dual-mode X-ray direct detection

Abstract

X-ray direct detectors, which may directly convert X-rays into electrical signals through semiconductors, are highly desirable for early cancer screening and other applications. Prevailing commercial amorphous Se detectors still suffer from low phase instability and low sensitivity, while the emerging perovskite detectors are subjected to low chemical instability despite high sensitivity and low detection limits. This work reports a viologen-templated Dy(III)-based metal–organic framework (MOF) with radiochromic semiconductive properties and high framework thermal (up to approximately 280 °C) and radiation stability. Its single-crystal detector has an exceptional sensitivity (6385 μC Gy⁻¹ cm⁻² at 271 V cm⁻¹) to tungsten anode X-rays compared to amorphous Se (20 μC Gy⁻¹ cm⁻² at −10 000 V cm⁻¹), single-crystal MAPbI₃ perovskite (968.9 μC Gy⁻¹ cm⁻² at −10 V cm⁻¹), and other single-crystal or pellet MOF-based direct detectors (20–3500 μC Gy⁻¹ cm⁻²). Moreover, it exhibits a rapid photochromic response within 10 seconds upon X-ray irradiation and can naturally fade for easy reuse. This property offers the convenience of quickly capturing object information through visual inspection and serves as an alternative means of direct detection outside of traditional electrical imaging methods.