Development Of Photoelectric Materials With Organic-inorganic Hybrid Perovskite Structure

Photoelectric materials with organic-inorganic hybrid perovskite structure are novel molecular-scale composites through organic and inorganic compounds' self-assembling.The layered perovskite framework comprised of metal halide octahedra provides a distinct set of advantages including good electrical mobility, mechanical and thermal stability,while organic component offers a number of useful properties including structural diversity and ease of processing et al.Its self-assembling quantum well structures of semiconducting inorganic sheets alternating with organic layers result in a larger exciton binding energy and unique electronic,optical and magnetic properties.Recently,it has received considerable attention due to its promising application prospect.Based on the basic hybrid perovskite structure,this dissertation concentrated on structural engineering of photoelectric materials with organic-inorganic hybrid perovskite structure and then engineering the physical characteristics.Series of organic compounds including linear alkyl amines,N-(1-naphthyl)ethylenediamine, 3-(2-Aminoethyl)indole and carbazole-linked amine were integrated with various metal halide to form the hybrid perovskite structure materials.We studied the influence of organic and inorganic components on the structure,thermal,optical,and electronic properties of the hybrid materials.We also studied unusual structural and electronic attributes between organic-inorganic components.Three series of photoelectric materials with organic-inorganic hybrid perovskite structure had been prepared.First,hybrid materials based on linear alkyl amines had been prepared by reacting linear alkyl amines with metal halide.Powder X-ray diffraction measurements indicated hybrid materials based on linear alkyl amines all had formed <100>-oriented two-dimensional layered perovskite structure with MX₄²-layers of comer-sharing metal halide octahedra alternating with organic cation bilayers(for monofunctionalcations)or monolayers(for bifunctional cations).By altering the carbon chain length,substitutional group on carbon chain,monoamine cations or biamine cations,metal cation and halide anion,we could adjust the interlayer distance,linear alkyl amines' conformation and the interaction between linear alkyl amines and metal halide octahedra.Secondly,the more interesting hybrid materials were obtained when N-(1-naphthyl)ethylenediamine was integrated with various metal halide,in which (C₁₂H₁₅N₂·HCl)₂PbCl₄,(C₁₂H₁₅N₂·HCl)₂CuCl₄ and(C₁₂H₁₅N₂·HCl)₂SnCl₄ formed <100>-oriented two-dimensional layered perovskite structure,while(C₁₂H₁₆N₂)₂PbI₆ and(C₁₂H₁₆N₂)₂PbBr₆ formed <111>-oriented zero-dimensional layered perovskite structure.It is the first time that the <111>-oriented zero-dimensional layered perovskite structure with chromophore-containing amine was prepared.MX₄²- layers of isolated metal halide octahedra alternated with organic cation bilayers comprised of N-(1-naphthyl)ethylenediamine in <111>-oriented zero-dimensional layered perovskite structure.The organic molecules adopted a head to tail arrangement and the naphthyl units were interleaved and parallel to each other.Three isolated PbX₆⁴-octahedra had been linked by one organic molecule via hydrogen-bond.The face-to-faceÏ€-Ï€stacking interaction between the adjacent naphthalene rings which aid the major N-H...X hydrogen bond stabilized 0-D perovskite structure.Thirdly,the most complicated <111>-oriented zero-dimensional layered perovskite structure hybrid material(C₂₀H₂₆N₄·HI)₂PbI₆ was gained when 3-(2-Aminoethyl)indole was integrated with PbI₂.In the concentrated HI solution,one double bond of indole ring broke and two 3-(2-Aminoethyl)indole molecule came into being one complicated molecule.The new complicated molecule immerged into PbI₂ and formed(C₂₀H₂₆N₄·HI)₂PbI₆.There were iodic ion that were not coordination with Pb²⁺in(C₂₀H₂₆N₄·HI)₂PbI₆.All of the conjugated tings were not parallel and the organic cation adopted a herringbone arrangement.Organic cation bilayers were connected by edge-to-face(tilted-T)aromatic interactions and the hydrogen-bond between the organic cation and iodic ion which stabilized 0-D perovskite structure.The effect of the carbon chain length,substitutional group on carbon chain, monoamine or biamine cations,chromophore,metal cation and halide anion on the thermal properties of the hybrid materials had been studied by thermogravimetric analysis and differential scanning calorimeter measurements.It was shown that the hybrid materials had a good thermal stability with the decomposition temperature higher than 180℃.Hybrid materials based on linear alkyl Amines had from one to three solid-state phase transition and one melting transitions.Hybrid materials based on chromophore-containing amines decomposed step-by-step(first loss of the isolated HX,then loss of the organic component,and finally the evaporation of PbX₂)and had one melting transitions but no solid-state phase transition.The effect of organic component,inorganic component and structure on the optical properties of hybrid materials had been studied by UV-Vis absorption, photoluminescence spectra and the band structures calculated.It was shown that hybrid materials based on linear alkyl amines self assembled a typeâ… quantum well structure resulting in larger exciton binding energy and exhibited the strong absorption and emission in room temperature.Hybrid materials based on chromophore-containing amines self assembled a typeâ… orâ…¡quantum well structure. It exhibited an exciton peak arising from the metal halide sheets along with absorption from the chromophore moiety.Photoluminescence spectra and the calculated band structures indicated that(C₁₂H₁₅N₂·HCl)₂PbCl₄ and(C₁₈NH₂₀-NH₃)₂PbCl₄ self assembled a typeâ… quantum well structure and exhibited the fluorescence stronger than that of the chromophore,which clearly represented an energy transfer between the shifted inorganic excitonic band and the organic chromophore.While (C₁₂H₁₆N₂)₂PbBr₆,(C₁₂H₁₆N₂)₂PbI₆,(C₂₀H₂₆N₄·HI)₂PbI₆ and(C₁₈NH₂₀-NH₃)₂PbCl₂I₂, self assembled a typeâ…¡quantum well structure where the lowest energy state for electrons and holes may be such that electrons experience a driving force toward the organic component,while holes are driven toward the inorganic component.Charge separation between the organic and inorganic components inhibits overlap of the electron and hole wave functions and may therefore decrease the probability of the carriers recombining radiatively.The hall electrical resistivity and surface photovoltaic measurements indicated that the hybrid materials were p semiconductors.Hybrid materials based on chromophore-containing amines had three peaks in surface photovoltaic spectra and photoconductivity properties.