使用無毒溶劑系統以狹縫式法製備高效率鈣鈦礦太陽能電池

Abstract

高效率鈣鈦礦太陽能電池因為可以使用溶液製程，因此很有潛力成為下個世代低成本太陽能電池的主流。然而，目前最高效率25.2 %所使用的製程為不適合大面積連續量產與高材料浪費率的旋轉塗佈法。狹縫式塗佈法製程能夠達到與旋轉塗佈相同的薄膜品質與低材料浪費率。目前在文獻中以狹縫式塗佈法所製備的P-I-N鈣鈦礦太陽能電池最高效率為15.5 %，其中只有鈣鈦礦主動層是以狹縫式塗佈法所製備，載子傳輸層與界面修飾層皆還是以不利於量產的製程所製備。此外這個結果，需要在量產時會增加氣氛控制成本的手套箱製備。另外他們的製程配方中含有像是二甲基甲醯胺 (DMF)與氯苯 (CB)等不適合於工業量產的有毒溶劑。因此本研究的目標是使用無毒的溶液配方，在大氣下以狹縫式塗佈法製備高效率P-I-N鈣鈦礦太陽能電池。 我們有系統地研究以狹縫式塗佈法製備除了電極外四層的溶液配方與最佳的製程參數。透過分析每一層薄膜其光學性質、電性、表面形貌與結晶度，來最佳化溶液配方以及製程參數。本研究所使用的電池元件結構為FTO/NiOX/MAPbI3/PCBM/ TBAOH/Ag。在以狹縫式塗佈法製備NiOX電洞傳導層中，能夠達到與旋轉塗佈法接近的效率15.43 %。使用無毒溶劑配方二甲基亞碸 (DMSO)與2-甲基吡嗪 (2-MP)取代二甲基甲醯胺，在體積比7:3的條件以狹縫式塗佈法製備的鈣鈦礦薄膜，最高效率達到16.09 %。使用鄰二甲苯 (o-Xylene)取代氯苯的最高效率可以達到15.95 %。藉由TBAOH取代PEI可以避免鈣鈦礦層被破壞且最高效率可以達到13.85 %。 最後結合了我們所建立以狹縫式塗佈法製備除了電極外四層的技術，在有效面積0.09 cm2 與0.75 cm2下分別達到13.85 %及13.52%的效率，且元件沒有出現任何遲滯現象。根據文獻，我們所達到的效率在以狹縫式塗佈法製備除了電極外每一層的鈣鈦礦太陽能電池中是最高的。總結來說，我們能夠在大氣下以可量產的狹縫式塗佈法製備鈣鈦礦太陽能電池，展現了未來能夠商業化的潛力。

High power conversion efficiency (PCE)perovskite solar cell has emerged as a next generation low cost solar cell due to it can be fabricated from solution process. However, the reported high PCE of 25.2 % was using spin coating method which cannot scale up for large area continuous production process and waste material. The slot-die coating process can reach the film quality of spin coating but no material waste. The state of the art of PCE of 15.5 % was reached when the solar cell was fabricated using slot-die coated perovskite, spin coated charge transport layer and work function modified layer. Futhermore, this result was obtained from the process operated in the inert atmosphere which will add the production cost. The solution formulations contain toxic solvents such as dimethylformamide (DMF), chlorobenzene (CB) that are undesirable for industrial manufacturing. It is our goal to develop adequate solution formulations and process parameters for all four layers of P-I-N perovskite solar cell using slot-die technique operating in ambient environment. We systematically carried out all the experimental parameters for solution formulations and coating process of each layer. The results films were carefully examined for their electronic and optical properties; morphology and crystallinity in order to optimize the solution formulations and process parameters. The device has the structure of FTO/NiOX/MAPbI3/PCBM/TBAOH/Ag. The slot-die coated hole transport layer of NiOX reached similar device PCE of 15.43 % and the spin coated film. The slot-die coated perovskite film can reach a PCE of 16.09 % using the non-toxic solution formulation of dimethyl sulfoxide (DMSO) and 2-methylpyrazine (2-MP) at volume ratio of 7:3 instead of toxic DMF. The slot-die coated electron transport layer PCBM can obtain a PCE of 15.95 % using non-toxic o-xylene instead of toxic CB. By replacing work function modifier polyethylenimine (PEI) by terabutylammonium (TBAOH), a PCE of 13.85 % was reached without damaging the peovskite layer. By combining all four layer slot-die coating technique to fabricated solar cell except the electrode, the PCE of 13.85 % and 13.52 % have been reached for solar cell size of 0.09 cm2 and 0.75 cm2, respectively. The devices exhibit no hysteresis. According to the best of our knowledge, the rsults are the highest in the slot-die fabricated perovskite solar cells. In conclusion, we have demonstrated a scalable slot-die process for the fabrication of perovskite solar cell in ambient environment which has potential to be commercialized.