| 摘要: | 鈣鈦礦太陽能電池(Perovskite Solar Cells, 簡稱PSCs)常用的電洞傳遞材料(HTM)有金屬氧化物、有機小分子、及有機高分子，其中有機高分子HTM具有高耐熱性、高疏水性、易製備成連續且高品質的薄膜等特性，可以提高PSC元件的光伏表現。本研究以實驗室自行合成的高分子P15做為電洞傳遞層(HTL)。P15是疏水性材料，鈣鈦礦是親水性材料，所以將P15旋塗至鈣鈦礦時會有界面不相容的問題，導致光電轉換效率(PCE)僅有15.08%，因此在P15及鈣鈦礦之間沉積一層兩性的高分子PDTON;或著將P15與PDTON混合後作為電洞傳遞層(HTL)。與純P15作為HTL時相比，PDTON做為界面層時P15的電洞遷移率為原本的1.5倍，PDTON與P15混合做為HTL時，電洞遷移率為原本的2.5倍;對應到PL及TRPL，PDTON做為界面層或與P15混合時皆有較低的螢光強度及載子壽命(1.79 ns減少至1.24及0.92 ns)。GIWAXS中顯示PDTON做為界面層或與P15混合時，接有較高的結晶度，代表高分子薄膜的品質較好。同時PDTON親水端的氧及氮也可與鈣鈦礦膜中配位未飽和的Pb2+作用，從FTIR中觀察到PDTON與PbI2混合後，其C-N及C-O鍵往低波數位移，從XPS中觀察到鈣鈦礦膜中鉛的4f電子的binding energy有往低能量位移0.2 eV，其缺陷密度也從5.56*10^15 cm^-3降低至1.54*10^15 cm^-3。以P15做為HTL並經由PDTON做界面修飾後所組裝的元件的最高光電轉換效率達15.92%，PDTON與P15混合做為HTL所組裝的元件的最高光電轉換效率達18.82%。P15做為HTL所組裝的元件未封裝放置於相對溼度20%、溫度30℃的環境下在經過22個小時後維持原效率的47%，而PDTON與P15混合做為HTL所組裝的元件經過22小時後維持原效率的59%， PDTON做為界面層並以P15做為HTL所組裝的元件經過22小時後維持原效率的59% ;Metal oxides, organic small molecules, and organic polymers are commonly used as hole transport materials (HTMs) for perovskite solar cells (PSCs). Among them, organic polymer HTMs have high thermal stability, hydrophobicity, and a continuous thin films can be easily formed, which can enhance the photovoltaic performance of PSCs. In this study, a D-A type conjugated polymer P15, developed by our laboratory, was used as the hole transport material (HTM) for regular PSCs.P15 is a hydrophobic material, while perovskite is a hydrophilic material.When P15 is spin-coated onto perovskite, there has an interface incompatibility issue, resulting in a low power conversion efficiency (PCE) of 15.08%. To solve this problem, a dual-function polymer called PDTON is deposited between P15 and perovskite to be an interface modification layer, or a mixture of P15 and PDTON was used as the HTL. Compared to using pure P15 as the HTL, the hole mobility of P15 was increased by 1.5 times when PDTON was used as the interface layer, and it increased by 2.5 times when P15 was mixed with PDTON as the HTL. Regarding photoluminescence (PL) and time-resolved photoluminescence (TRPL), both PDTON as the interface layer and the PDTON-P15 mixture exhibited lower fluorescence intensity and carrier lifetimes (reduced from 1.79 ns to 1.24 ns and 0.92 ns). GIWAXS analysis indicated higher crystallinity for the polymer films when PDTON was used as the interface layer or mixed with P15, suggesting improved film quality. However, the oxygen and nitrogen at the hydrophilic end of PDTON can coordinate with the unsaturated Pb2+ in the perovskite film. FTIR shows that after mixing with PbI2, the C-N and C-O bonds in PDTON shift to lower wavenumbers, and XPS shows that the binding energy of the Pb2+ 4f electrons in the perovskite film shifts to lower energy by 0.2 eV. As a result the defect density of perovskite film decreases from 5.56*10^15 cm^-3 to 3.11*10^15 cm^-3. Devices assembled with P15 as the HTL, modified with PDTON as the interface layer, achieved a maximum PCE of 15.92%, while devices assembled with a PDTON-P15 mixture as the HTL reached 18.82%. When exposed to an environment with 20% relative humidity and a temperature of 30°C for 22 hours, devices with P15 as the HTL maintained 47% of original efficiency, whereas devices with a PDTON-P15 mixture as the HTL maintained 59% of original efficiency, and those with PDTON as the interface layer and P15 as the HTL also maintained 59% of original efficiency. |
