Charge compensation via tetravalent doping for high-efficiency Mn2+-activated inorganic double perovskites toward high-resolution X-Ray imaging

Abstract

In recent years, lead-free halide double perovskite 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, all of which are essential for high-temporal-resolution radiation detection. Although nanostructured scintillators achieve exceptional optical uniformity, their nanocrystalline forms exhibit inherent limitations in terms of light emission intensity and overall scintillation efficiency. A critical limitation of X-ray flat-panel minidetectors is the absence of novel engineering approaches to amplify radioluminescence capabilities. Herein, we engineered a charge compensation strategy for Cs₂AgInCl₆ double perovskite NCs through co-doping tetravalent ions with Mn²⁺ emissive centers to stabilize the heterovalent substitution of In³⁺ sites with Mn²⁺. The co-doping of Zr⁴⁺ or Ce⁴⁺ enhanced Mn²⁺-activated emission and induced sequential improvements in photoluminescence lifetime and quantum yield for CAIC:Mn²⁺, CAIC:Mn²⁺,Zr⁴⁺ and CAIC:Mn²⁺,Ce⁴⁺. XPS analysis confirmed 1.46-fold (CAIC:Mn²⁺,Zr⁴⁺) and 1.59-fold (CAIC:Mn²⁺,Ce⁴⁺) increases in the effective Mn²⁺/Mn⁴⁺ doping concentration relative to CAIC:Mn²⁺. Ce⁴⁺ effectively suppressed Mn²⁺ oxidation to higher valence states, enhancing the Mn²⁺/Mn⁴⁺ ratio by 3.4 times. The CAIC:Mn²⁺,Ce⁴⁺@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.