RESUMO
The long charge carrier lifetime of the hybrid organic-inorganic perovskites (HOIPs) is the key for their remarkable performance as a solar cell material. The microscopic mechanism for the long lifetime is still in debate. Here, by using a muon spin relaxation technique that probes the fluctuation of local magnetic fields, we show that the muon depolarization rate (Δ) of a prototype HOIP methylammonium lead iodide (MAPbI3) shows a sharp decrease with increasing temperature in two steps above 120 K and 190 K across the structural transition from orthorhombic to tetragonal structure at 162 K. Our analysis shows that the reduction of Δ is quantitatively in agreement with the expected behavior due to the rapid development of methyl ammonium (MA) jumping rotation around the C 3 and C 4 symmetry axes. Our results provide direct evidence for the intimate relation between the rotation of the electric dipoles of MA molecules and the charge carrier lifetime in HOIPs.
RESUMO
Ytterbium-doped cesium lead halides are quantum cutting materials with exceptionally high photoluminescence quantum yields, making them promising materials as scintillators. In this work, we report ytterbium-doped cesium lead chloride (Yb3+:CsPbCl3) with an X-ray scintillation light yield of 102,000 photons/MeV at room temperature, which is brighter than the current state-of-the-art commercial scintillators. The high light yield was achieved based on a novel method of synthesizing Yb3+:CsPbCl3 powders using water and low-temperature processing. The combination of high light yield and the simple and inexpensive manufacturing method reported in this work demonstrates the great potential of Yb3+:CsPbCl3 for scintillation applications.