| Organic-inorganic hybrid materials with perovskite-like structure can combine the performance advantages of organic and inorganic components at the molecular level,show good semiconductor characteristics and thermal stability,as well as easy processing and good film-forming properties,and show broad application prospects.Especially in recent years,methylaminium lead triiodide and formamidinium lead triiodide have been successfully applied as absorbers in solar photovoltaic field,which has caused a research upsurge of Perovskite-type functional materials.In addition to being applied to solar cells,hybrid perovskites have great applications in the field of optoelectronic devices,such as field effect transistors,light-emitting diodes,lasers,and photodetectors.In this paper,four flexible organic amines,N-methylcyclohexylamine,isoamylamine,N,N-dimethylcyclohexylamine and N-methyl1,3-propanediamine,were used as templates to synthesize a series of hybrid perovskite compounds.The crystal structure,optical properties,dielectric properties,thermal properties and semiconductor properties of these hybrid perovskite compounds were systematically studied.?1?Based on N-methylcyclohexylamine,compounds with perovskite-like structure(C6H11NH2CH3)PbBr3?1?and(C6H11NH2CH3)4Pb3I10?2?were synthesized.The results of specific heat and differential scanning calorimetry?DSC?showed that:Reversible structural phase transitions occurred near 290 K and 254 K,respectively.The temperature-dependent single crystal structure analysis confirmed that the ordered-disorder transition of organic cations is the main reason inducing the phase transitions.Further,we replaced the organic amine in the compound 1 with N,N-dimethylcyclohexylamine to obtain a ferroelectric compound[C6H11NH?CH3?2]PbBr3?3?.DSC and variable temperature dielectric spectroscopy indicated that the Curie phase transition temperature?Tc?of the compound was 320 K,and the crystal space group changed from P21?T<Tc,ferroelectric phase?to P212121?T>Tc,paraelectric phase?,belonging to One of 88 ferroelectric phase transitions?Aizu symbol is 222F2?.In addition,a significant pyroelectric effect was observed near the Curie temperature,and the spontaneous polarization was about 0.9?C/cm2.?2?A variety of Ruddlesden-Popper type two-dimensional layered perovskite compound?A??2?A?n-1MnX3n+1 was synthesized by using isopentylamine as organic ligand,and two-dimensional monolayer hybrid perovskite??CH3?2CH2CH2CH2NH3?2PbI4?4?and two-dimensional bi-layer hybrid perovskite??CH3?2CH2CH2CH2NH3?2?CH3NH3?Pb2I7?5?were successfully obtained.By means of chemical method,the effective regulation of the optical bandgap,conductivity and photoelectric response of the compounds is realized,and it is found that compound 5 has better photoelectric detection performance.In addition,we also obtained Dion-Jacobson type two-dimensional layered perovskite?CH3NH2CH2CH2CH2NH3?2PbBr4?6?using N-methyl 1,3-propanediamine.The compound exhibits excellent photoelectric response and stability,and has potential applications in photoelectric detection,polarized light detection and other fields.?3?Using N-methyl 1,3-propanediamine as organic ligand and BiI6 coordination octahedron as inorganic skeleton,a lead-free compound?CH3NH2CH2CH2CH2NH3?BiI5?7?with one-dimensional chain perovskite-like structure was assembled and synthesized.At 200 K,the compound crystallized in the polar space group P21 with a wide absorption range and a band gap value of about 1.83 eV.The large-sized high-quality single crystal obtained by slow cooling shows a low trap density(3.6×1011 cm-3)and higher hole mobility(1.42 cm2 V-1 s-1).The crystal device assembled based on this compound exhibits good photoelectric response characteristics,and particularly exhibits a certain application potential in the fields of absorption and detection of high-energy X-rays. |
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