Water-Stable and Sensitive X-ray Detectors by Supramolecular Interaction-Enhanced Polyoxometalates

Polyoxometalates (POMs) have shown prominence in the field of semiconductive materials in recent years. However, electronic applications based on these emerging materials are still in their early stages. Here, a sensitive and water-stable F-PEA-ZnW₁₂ X-ray detector has been designed and constructed for hard X-ray detection and imaging. Supramolecular interactions of H···O bonding, electrostatic, and anion-π interactions not only enable FPEA-ZnW₁₂ excellent water stability but also shorten the distance between [ZnW₁₂O₄₀]^6- clusters, which reduces ion migration and dark current simultaneously, resulting in the conductivity of 3.2 × 10^-11 S cm^-1. Furthermore, the heteropoly blue formed on the surface of the O-FPEA-ZnW₁₂ wafer device promotes the effective separation and extraction of X-ray-induced carriers, enhancing the sensitivity for X-ray detection. The R/O-FEPA-ZnW₁₂ wafer device yields a high sensitivity of 3.1 × 10⁴ μC Gy_air^-1 cm^-2 with the lowest detectable dose rate of 69 nGy_air s^-1 under 120 kV hard X-ray irradiation. In addition, the O-FPEA-ZnW₁₂ wafer detector exhibits the potential for X-ray detection in water with a sensitivity of 1.0 × 10⁴ μC Gy_air^-1 cm^-2. Moreover, the fabricated POM X-ray detector shows excellent X-ray imaging capability and long-term operational stability without any attenuation of 1 year exposure to air without any encapsulation.