一般式鈦礦太陽能電池(Perovskite solar cells，簡稱PSCs)當中的鈣鈦礦膜在製備時常使用非揮發性溶劑(如：DMF和DMSO)溶解鈣鈦礦前驅物，這些非揮發性溶劑需要透過反溶劑以及高溫退火等方式移除，並且製膜需在手套箱中進行，此複雜且高成本的處理方式使得PSC在商品化過程中受到限制。本研究在大氣下，以揮發性液體做為可快速蒸發的溶劑，使鈣鈦礦快速結晶而不需使用反溶劑，並讓鈣鈦礦膜的製備可在大氣下操作，不受到水氣及氧氣的影響製備出高品質的鈣鈦礦膜。為了提高元件的效率，以本實驗室自行合成之分子BT-IDT做為鈣鈦礦與電洞傳遞層之間的界面修飾，期望以BT-IDT上的CN-基團以及噻吩上的S原子之孤對電子，與鈣鈦礦層中未配位飽和的Pb2+作用，以達到鈍化鈣鈦礦的效果，然而隨著實驗的進行發現元件效率的提高並不是因為BT-IDT分子的界面修飾，而是透過延遲退火提供鈣鈦礦膜足夠的時間晶粒生長。SEM圖顯示延遲退火的鈣鈦礦膜平整緻密，以其為吸收層所組裝之元件光電轉化效率可達22.8%，比直接退火的鈣鈦礦膜所組裝之元件的20.7%增加了約10%。從XRD圖可以看到不管是直接退火或是延遲退火製備的鈣鈦礦膜都沒有PbI2的繞射峰，而有延遲退火的鈣鈦礦膜其 (110) 面的繞射峰強度比直接退火的鈣鈦礦膜強，表示鈣鈦礦膜的結晶度更好，延遲退火30分鐘所製備的鈣鈦礦膜的結晶區塊為23.4 nm，比直接退火所製備的鈣鈦礦膜的結晶區塊(為22.0 nm)大，體現在所組裝之元件的FF值 (從原本的73%增加至78%)。延遲退火的鈣鈦礦膜有較強的PL強度以及更長的激子半生期，這些數據都顯示延遲退火所製備的鈣鈦礦膜的品質較好，載子在膜上傳遞時能量損失較少，增加所組裝之元件的Voc值(從1.13 V增加至1.16 V)，因此整體元件效率增加10%。;Perovskite film in perovskite solar cells (PSCs) is generally prepared by spin-coating from its precursor solution using non-volatile solvents (such as Dimethylformamide or Dimethyl sulfoxide) to dissolve the perovskite precursor salts. These non-volatile solvents need to be removed by anti-solvent and high-temperature annealing, which need to be carried out in a glove box. This complex and high-cost processing method could be a problem for industrial development. In this study, quick crystallization of perovskite films was achieved by using volatile solvents without using an anti-solvent under ambient environment without affecting by moisture and oxygen. Therefore, high-quality perovskite films were prepared. In order to improve the efficiency of the device, BT-IDT, a molecule synthesized in our laboratory, was used as the interface (between the perovskite and the hole transport layer (HTL)) modification agent. The CN-group in BT-IDT and the lone pair electrons on S atoms of thiophene could interact with the coordination unsaturated Pb2+ in the perovskite film to achieve the passivation. However, later studies found that the improved efficiency of the device is not due to the interphase modification by BT-IDT but due to the delayed annealing of the wet film to provide sufficient time for grain growth. SEM images show a flatter and denser perovskite film. The PSCs based on perovskite film prepared by using volatile solvent and delay annealing exhibit the highest power conversion efficiency (PCE) of 22.8%, which is higher than 20.7% of cells assembled by using directly annealing perovskite film as an absorber. XRD patterns show that both perovskite films prepared by direct annealing and delayed annealing have no PbI2 diffraction peak but the (110) direction intensity of perovskite films prepared by delayed annealing is stronger than the prepared by direct annealing. The domain size of the perovskite films prepared by 30 minutes delayed annealing is 23.4 nm which is larger than that (22.0 nm) of the perovskite films prepared by direct annealing, which reflected in the FF value of the corresponding device (increased from 73% to 78%). The delayed annealed perovskite film has a stronger photoluminescence intensity and a longer exciton half-life than the film prepared by direct annealing, which indicates that the quality of the former perovskite film is better. Therefore, the Voc value of PSCs increases to 1.16 V due to the carriers travel through perovskite film with less energy loss. Overall the PSCs achieved the highest PCE of 22.8%.
