Here we report X- and gamma-ray scintillation properties from solution-processable perovskite (SPP) halide single crystals and quantum dots. We tune the properties of single crystals by replacing the cation, changing the organic ammonium cation spacer, and varying the halide anion. For quantum dots, we tune the properties by changing the halide ion composition while we also try to replace the lead with the bismuth. Finally, we summarize the advantages and disadvantages of SPP single crystals and quantum dots to pave the way the research for the new high light yield scintillators.
Due to the large exciton binding energy, two-dimensional perovskite has demonstrated the potential as high-performance while low-cost scintillator. In our experiment, first we systemically investigate the effect of Li-ion dopant in phenethylammonium lead bromide, (PEA)2PbBr4 perovskite crystals under soft X-ray radiation of 15 keV. Successful inclusion of Li at four doping concentrations was confirmed by X-ray photoelectron spectroscopy. Li doping causes no substantial change in the crystal structure judging from the X-ray diffraction pattern but induces stronger emission tail as observed in the temperature-dependent X-ray luminescence (XL). Upon higher Li concentration, the emissions become broader due to possible Li trap emission as indicated by increasing traps induced by more Li in the X-ray thermoluminescence spectra. The behavior of negative thermal quenching is found in the XL and it can yield a benefit such as the possible light yield improvement in the X-ray imaging application. After the soft X-ray characterizations, we further explore our crystals in gamma-ray detection. In the gamma-ray pulse height measurement, relatively broad peaks can be resolved with the light yield of about 10,000 photons/MeV at 662 keV. The result from alpha particle pulse height measurement also indicates that we could even utilize our crystals in alpha particle detection at 5.8 MeV. Based on this feature and Li-ion capability as dopants, our crystals promise a good performance in thermal neutron detection. Finally, we can realize a versatile radiation detector that works in broad range of energy from soft to high energy radiation.
Systematic investigation of temperature-dependence on thermal quenching of X-ray luminescence (XL) from various single perovskite crystals was carried out. In the family of methylammonium lead halide perovskites (MAPbX3, MA = methylammonium, X= Cl, Br or I), the quenching temperature of XL decreases from Cl to I. According to our analysis, such behavior is strongly affected by their corresponding decrease of thermal activation energy ▵Eq from 53 ± 3 to 6 ± 1 meV. Different concentrations of Bi3+-doped MAPbBr3 are also prepared and both four-point probe measurement and X-ray thermoluminescence (TL) confirms the successful doping. When we dope MAPbBr3 with Bi3+, Γ0/Γv increases to 78 ± 18 for crystal with Bi/Pb ratio of 1/10 in precursor solution.