Scalable X-ray scintillators with bright singlet-triplet hybrid self-trapping excitons

Abstract

Size-scalable X-ray scintillators with high transparency and robust photon yield allow for imaging large objects with greater precision and detail. Solution-processable scintillators, typically crafted from quantum dots (QDs), are promising candidates for highly efficient scintillation applications. However, the restricted size and low transparency in QD-based scintillators lead to less efficient X-ray imaging for large objects requiring high resolution. Herein, we demonstrate a meter-scale ZnO QD scintillator with a visible range transmittance exceeding 96%, featuring bright singlet-triplet hybrid self-trapping excitons (STEs). The quantum yields (QYs) of singlet excitons and triplet excitons are 44.7% and 26.3%. Benefiting from a large Stokes shift and bright triplet excitons, the scintillator has a negligible self-absorption and elevated photon yields. Additionally, the scintillator exhibits exchange invariance, demonstrating identical optical performance upon exchanging the coordinates (r) of the QDs. Featuring bright singlet-triplet hybrid STEs and high transparency, the scintillator achieves high resolution X-ray imaging of 42-line pairs per millimeter (42 lp mm⁻¹) at a meter scale. Moreover, demonstrations of 5000 cm² X-ray imaging and real-time dynamic X-ray imaging are presented. The lowest detectable dose rate for X-ray detection is as low as 37.63 ± 0.4 nGy s⁻¹. This work presents a novel sizable and transparent scintillator with bright singlet-triplet hybrid STEs, showcasing their potential in high-resolution and sizable object X-ray imaging.