X-ray scintillation in lead-free double perovskite crystals

Metal halide perovskites have shown great performance for various applications,including solar cells,light emitting diodes,and radiation detectors,but they still suffer from the toxicity of lead and instability.Here we report the use of lanthanide series as trivalent metals to obtain low toxicity and highly stable double perovskites(Cs_2NaLnCl_6,Ln=Tb or Eu)with high scintillation light yield.The crystals exhibit typical f-f transitions of lanthanide cations,while Cs_2NaTbCl_6exhibits strong green photoluminescence,and Cs_2NaEuCl_6exhibits red photoluminescence.Under X-ray radiations,the light yield of Cs_2NaTbCl_6reaches46600 photons MeV^(-1),much higher than that of the commercially used(Lu,Y)_2SiO_5:Ce^(3+)crystals(LYSO,28500 photons MeV^(-1)),and previously reported lead-based perovskites(14000 photons MeV^(-1)).As a new member of lead-free perovskites,lanthanide-based double perovskites open up a new route toward radiation detections and potential medical imaging.

Antimony doped Cs2SnCl6 with bright and stable emission

Lead halide perovskites,with high photoluminescence efficiency and narrow・band emission,are promising materials for display and lighting.However,the lead toxicity and environmental sensitivity hinder their potential applications.Herein,a new antimony・doped lead-free inorganic perovskites variant Cs2SnCl6:xSb is designed and synthesized.The perovskite variant Cs2SnCl6:xSb exhibits a broadband orange-red emission,with a photoluminescence quantum yield(PLQY)of 37%.The photoluminescence of Cs2SnCl6:xSb is caused by the ionoluminescence of Sb3+within Cs2SnCl6 matrix,which is verified by temperature dependent photoluminescence(PL)and PL decay measurements.In addition,the all inorganic structure renders Cs2SnCl6:xSb with excellent thermal and water stability.Finally,a white light-emitting diode(white-LED)is fabricated by assembling Cs2SnCl6:0.59%Sb,Cs2SnCl6:2.75%Bi and Ba2Sr2SiO4:Eu2+onto the commercial UV LED chips,and the color rendering index(CRI)reaches 81.

Inorganic antimony halide hybrids with broad yellow emissions

Lead halide perovskites exhibit unexceptionable photoelectric properties.However,these materials are unsatisfactory in terms of stability and toxicity.Herein,we report Rb7 Sb3 Cl16 as a new kind of lead free perovskite variants.This material can be easily obtained through hydrothermal reactions.The composition is determined through structure refinement,elemental analysis and X-ray photoelectron spectra.Rb7 Sb3 Cl16 exhibits a broad yellow emission at 560 nm,with a Stokes shift of 175 nm and a photoluminescence quantum yield(PLQY)around 26%.Rb7 Sb3 Cl16 also shows good thermal and water stability due to its inorganic composition.White light-emitting diodes(LEDs)are constructed by combining Rb7 Sb3 Cl16 as yellow phosphors,our previously reported Cs2 SnCl6:2.75%Bi as blue phosphors,and commercial UV LED chips as the excitation source,producing a white light with the Commission Internationale de’Eclairage(CIE)color coordinates at(0.39,0.38).

Oxide perovskite Ba_(2)AgIO_(6)wafers for X-ray detection

X-ray detection is of great significance in biomedical,nondestructive,and scientific research.Lead halide perovskites have recently emerged as one of the most promising materials for direct X-ray detection.However,the lead toxicity remains a worrisome concern for further commercial application.Great efforts have been made to search for lead-free perovskites with similar optoelectronic properties.Here,we present a lead-free oxide double perovskite material Ba2AgIO6 for X-ray detection.The lead-free,all-inorganic nature,as well as the high density of Ba2AgIO6,promises excellent prospects in X-ray applications.By employing the hydrothermal method,we successfully synthesized highly crystalline Ba2AgIO6 powder with pure phase.Furthermore,we prepared Ba2AgIO6 wafers through isostatic pressure and built X-ray detectors with Au/Ba2AgIO6 wafer/Au photoconductive structure.The as-prepared X-ray detectors showed a sensitivity of 18.9μC/(Gyair$cm2)at 5 V/mm,similar to commercialα-Se detectors showcasing their advantages for X-ray detection.