Preparation And Structure Of MnX₂,PbX₂ Series Organic-inorganic Perovskite-type Materials

Organic-inorganic layered perovskite-type materials integrate useful organic and inorganic characteristics on a molecular level. Organic molecules provide structural diversity, plastic mechanical properties, large polarizability, ease of processing and high fluorescence efficiency, whilst inorganic materials offer the potential for a wide range of electronic properties (enabling the design of insulators, semiconductors, and metals), magnetic and dielectric transitions, substantial mechanical hardness, and thermal stability. Special properties and functions would be got if the hybrid materials could combine desirable physical properties characteristic of both components within a single composite. The inorganic components mainly reported in this study are manganese halides (MnX₂) and lead halides (PbX₂), and an exposition of organic-inorganic hybrid materials was made on preparation and characterization of hybrid layered perovskite powder crystals which has single-layer or multilayer perovskite structure and the process in making thin-films. PbI₂ strong coordination trend was used and a new type of PbI₂ system complex was prepared and characterized.Powder crystals XRD results showed the synthesized samples have layered crystal structure, X-ray diffraction profile indicates that there is basically only diffraction peaks from (0 0 2l) series crystal face. R-NH₂·HX (except CH₃NH₂·HX) series have analogous grow trends along (0 0 2l) direction comparing with organic-inorganic layered perovskite-type, and they plays a crucial template role in the organic-inorganic layered perovskite-type growing along (0 0 2l) direction.Genuine phases of Multilayer perovskite-type structure series is a bit difficult to get by solution reaction process since too quick reaction and asymmetry of every ingredient at the moment of mixing. What we got regularly is the mixed powder crystals with different inorganic perovskite-type structure. Comparing (C₁₂H₂₅NH₃)₂CH₃NH₃Pb₂I₇ with (C₁₂H₂₅NH₃)₂KPb₂I₇ by using powder crystal XRD, we may conclude that the exchange of A' cation has slight influence on the interlayer d-space.Thin films of organic-inorganic hybrid compounds (C_nH_2n+1NH₃)₂PbI₄ (n=6, 8,10, 12) were prepared by the spin-coating method, XRD profile indicats that the films were highly oriented. The quality of thin films becomes higher with the increase of n under the same spin-coating process. UV-Vis profile indicates that exciton absorption is more related to the band gap of inorganic layer, PL also shows that valence band forms by the hybridization of Pb (6s) orbit and I (5p) orbit, while the conduction band is originated form Pb(6p) orbit. So the emission of fluorescence light is mainly because of electron transmission within inorganic layers.Pbl2 series has relatively strong coordinate tendency with certain kinds of solvents, a novel coordination compound {[(Pbl2)(DMF)2]#H2O}n was prepared by taking advantage of this characteristic.