Highly sensitive indirect X-ray detector using an ultrasonically exfoliated MoS2 monolayer in the active layer

Abstract

This study demonstrates a significant enhancement in indirect X-ray detector performance through the incorporation of 25 nm MoS₂ monolayer nanosheets into PBDB-T:ITIC organic active layers, prepared via ultrasonic exfoliation and stepwise centrifugation. HR-TEM analysis confirms that the exfoliated MoS₂ maintains a 0.27 nm lattice d-space and a 2H-phase hexagonal structure, with XRD verifying monolayer stability. The hybrid active layer, added with 3 wt% 25 nm MoS₂, achieves a vertical charge mobility of 1.515 × 10⁻⁴ cm² V⁻¹ s⁻¹ and a defect density of 1.37 × 10¹⁶ cm⁻³, resulting in a 25.2% sensitivity improvement (1.804 mA Gy⁻¹ cm⁻²) compared to pristine active layers. This enhancement is attributed to quantum confinement effects expanding the bandgap to 1.85 eV and increasing spectral overlap efficiency to 92% with scintillator emissions. π-orbital alignment between MoS₂ and PBDB-T reduces series resistance to 376 Ω cm². This research presents a novel framework for designing 2D material-based radiation detectors, with potential applications in medical imaging and wearable monitoring systems.