| 摘要: | 鈣鈦礦太陽能電池是近五年來發展最快，也是備受矚目的新興材料之一，在文獻回顧中，我們發現從結晶的角度可以為鈣鈦礦太陽能電池帶入新思維，此研究可區分為三個部分，第一個部分是將研磨法應用於鈣鈦礦的合成中，我們研磨了三種不同組成的鈣鈦礦:CH3NH3PbI3、(C6H5CH2NH3)2PbCl4和CH3NH3PbI2Cl，從X光繞射分析(XRD)的圖譜中可以了解到研磨出的三組鈣鈦礦結構的訊號是可以對應到單晶繞射圖或是有屬於鈣鈦礦的訊號出現，從此結果可以得知研磨法可以用來做為鈣鈦礦的新材料篩選以及新溶劑的篩選方式。第二部分則是針對CH3NH3PbI3鈣鈦礦去作探討，利用實驗室常用的25種溶劑在25oC環境下分別對甲基胺碘(CH3NH3I)和碘化鉛(PbI2)去做溶劑篩選，從溶劑的篩選結果可以得知25種溶劑中對於甲基胺碘和碘化鉛是好的溶劑(溶解度 ≥ 5 mg/mL)或是差的溶劑(溶解度 ≤ 5 mg/mL)，對於甲基胺碘來說好的溶劑有13種、差的溶劑有12種，就碘化鉛而言，好的溶劑有3種，差的溶劑有22種，在實驗中可以選擇好的溶劑當成反應溶劑，而差的溶劑可以當成反溶劑去促使再結晶，試著去長出不含溶劑的鈣鈦礦，在第二部分的實驗中我們添加了甲基胺碘與碘化鉛共同的差溶劑去作為反溶劑，添加不同的反溶劑所得到的產物，經由FT-IR、PXRD、TGA和DSC鑑定後皆為CH3NH3PbI3鈣鈦礦的二甲基甲醯胺(DMF)的溶劑化物，最後，第三部分是探討退火的程序，觀察經由不同的升溫速率對CH3NH3PbI3鈣鈦礦結晶的影響，升溫速率分為快加溫(將CH3NH3PbI3鈣鈦礦的二甲基甲醯胺的溶劑化物放入已經預熱至100oC的烘箱)跟慢加溫(將CH3NH3PbI3鈣鈦礦的二甲基甲醯胺的溶劑化物放入30oC的烘箱中慢慢加熱至100oC，升溫速度為10oC/hr)，經過OM、UV/vis和PL的檢測之後，可以發現到升溫速率是需要被注意且進一步去控制的，從第三部分的實驗可以得知緩慢升溫的過程中，可以從CH3NH3PbI3鈣鈦礦的二甲基甲醯胺的溶劑化物慢慢的移除掉二甲基甲醯胺而不使晶格破裂損壞，破裂的晶格會影響到膜的平滑程度而導致能量轉換效率降低。;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. |
