| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程學系 === 104 === Perovskite, has recently been notable as an organic-inorganic hybrid semiconductor material. In this work we divided in three parts. Firstly, we introduced a neat and liquid-assisted grinding method into perovskite system. Three types of perovskites: CH3NH3PbI3, (C6H5CH2NH3)2PbCl4 and CH3NH3PbI2Cl were ground. PXRD showed that the solids made by the grinding method revealed some characteristic perovskite peaks indicating that both neat and liquid-assisted grinding method could be used in perovskite and solvent screening. Even though neat grinding method works, we still used liquid-assisted grinding method to suit wet chemistry. New materials and solvents can be used to synthesize perovskite. Secondly, basic information about perovskite such as methylammonium lead iodide (CH3NH3PbI3) by using initial solvent screening were investigated. 25 kinds of solvents were used to dissolve PbI2 and CH3NH3I at 25oC to construct Form Spaces, respectively. These solvents were chosen because they were commonly used in the laboratory. Solvents were one of important factors in the synthesis of perovskite. A solvent suitable for synthesis must be selected. Form Spaces showed which were good solvents (solubility ≥ 5 mg/mL) or bad solvents (solubility ≤ 5mg/mL). Good solvents could be used as a reagent, and bad solvents could be used as an antisolvent. According to the Form Space, PbI2 had 3 good solvents and 22 bad solvents, and CH3NH3I had 13 good solvents and 12 bad solvents. We found that regardless of which antisolvents were used, the same intermediate phase was crystallized out repeatedly and determined to be CH3NH3PbI3・DMF solvate if DMF was used as the crystallization solvent as identified by FT-IR, PXRD, TGA and DSC. Pure CH3NH3PbI3 crystals could not be found directly by solution crystallization. Thirdly, the annealing process were studied by different heating rates, such as rapidly heating (place the sample directly into a preheated oven at 100oC) and gradually heating (heated from 30o to 100oC, heating rate was about: 10 oC/hr). The results from the OM images, UV-vis absorption and photoluminescence spectra showed that the heating rate had to be controlled during annealing process. If the heating rate was increased gradually, DMF could be removed without breaking the crystal lattice. The broken crystal lattice could influence on the film morphology, worsened the film morphology, and also led to poor energy conversion efficiency.
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