Charge Compensation via Tetravalent Doping for High-Efficiency Mn 2+ -Activated Inorganic Double Perovskites toward High-Resolution X-Ray Imaging

Abstract

In recent years, lead-free halide double perovskites nanocrystals (NCs) have emerged as compelling scintillator candidates due to their high effective atomic number, ultrafast scintillation decay kinetics, eco-friendly composition, and bandgap tunability, which are essential for high-temporal-resolution radiation detection. While nanostructured scintillators achieve exceptional optical uniformity, their nanocrystalline forms inherently exhibit inherent limitations in light emission intensity and overall scintillation efficiency. A critical limitation in X-ray flat-panel minidetectors remains the absence of novel engineering approaches to amplify radioluminescence capabilities. Herein, we engineered a charge compensation strategy in Cs 2 AgInCl 6 double perovskite NCs through co-doping tetravalent ions with Mn 2+ emissive centers to stabilize the heterovalent substitution of In 3+ sites by Mn 2+ . The co-doping of Zr 4+ or Ce 4+ enhanced Mn 2+ -activated emission, and induced sequential improvements in photoluminescence lifetime and quantum yield for CAIC:Mn 2+ , CAIC:Mn 2+ , Zr 4+ and CAIC:Mn 2+ , Ce 4+ . XPS analysis confirmed 1.46-fold (CAIC:Mn 2+ , Zr 4+ ) and 1.59-fold (CAIC:Mn 2+ , Ce 4+ ) increases in effective Mn 2+ /Mn 4+ doping concentration relative to CAIC:Mn 2+ . The Ce 4+ effectively suppressed Mn 2+ oxidation to higher valence states, enhancing the Mn 2+ /Mn 4+ ratio by 3.4 times. The CAIC:Mn 2+ , Ce 4+ @PDMS scintillator film demonstrated a superior light yield of 16,807 photons MeV -1 , spatial resolution of 7.7 lp mm -1 , and detection limit of 619.2 nGy air s -1 .