부산대학교 도서관

One of the most anticipated candidates for lead-free halide perovskite for photovoltaic applications is Sn(II)-based halide. In this report four perovskites CH3NH3SnBr3, CH(NH2)2SnBr3, CH3NH3SnI3and CH(NH2)2SnI3were characterized by DTA, XRD, 81Br, 127I NQR and 119Sn NMR. A new synthetic approach was also proposed for the bromide analogs, in which only pure water was used as a solvent. Although, these four crystals belong to a cubic system at ambient temperature, only CH(NH2)2SnBr3showed a large lattice constant (a˜ 2ac) in which an isolated SnBr3-anion was confirmed. In order to detect 119Sn NMR, the addition of reduced agent SnF2was considerably effective to remove the high-frequency shift (Knight shift) and the broadening due to the half-metallic conductivity of the as-grown crystals.Four perovskites ASnX3(A = CH3NH3, CH(NH2)2, X = Br, I) were characterized by DTA, XRD, NQR and 119Sn NMR. All these crystals belong to a cubic system at RT, however, CH(NH2)2SnBr3cystal consists of an isolated SnBr3-anion. 119Sn NMR suggested that the addition of the reduced agent SnF2was effective to remove the half-metallic conductivity of the as-grown crystals.