有機鈣鈦礦/鐵鈀合金-異質雙層薄膜系統之熱穩定度、光學及磁性分析

Abstract

近期研究在有機鈣鈦礦材料上的能量轉換率、能隙的可調性及界面的載流能力有令人矚目的成果。有鑒於有機鈣鈦礦材料的特性，我們開始於物理氣相沉積製備的鐵鈀合金上利用旋塗法將MAPbBr3鈣鈦礦成長於頂層，形成有機鈣鈦礦/鐵鈀合金-異質雙層薄膜。而樣品的表面形貌藉由原子力顯微鏡(AFM)觀察到MAPbBr3鈣鈦礦以柱狀奈米結構且不均勻分布的方式成長於鐵鈀合金上方。 本實驗在於觀察樣品的磁性與光學在不同退火溫度下(100~170 ℃)的轉變。首先使用磁光柯爾顯微鏡發現矯頑場與磁光柯爾訊噪比隨著溫度有所改變。其中磁光柯爾訊噪比在100~120℃之間的變化量最為明顯。再來透過光致螢光(PL)的數據分析得到在100~120℃之間的光訊號強度下降較其他溫度區間明顯(約3倍) ，以上現象源自於在這期間MAPbBr3鈣鈦礦界面擴散至鐵鈀合金層。

Recent studies have shown promising results with regards to the power conversion efficiency, band-gap tunability, and interfacial charge carrier ability of organic lead halide perovskites. In light of these fundamental abilities, we fabricate a heterostructure thin film consisting of both magnetic and optical capabilities. The MAPbBr3 (perovskite) was spin-coated on top of the FePd alloy layer (deposited via PVD onto a SiO2 substrate). The atomic force microscopy (AFM) analysis reveals discrete pillar-like nanostructures of the perovskite material that occurs non-uniformly across the FePd under layer. When post-annealed to high temperatures (100-170˚C), the resultant magnetic hysteresis loops show the coercivity enlargement of FePd, with the interfacial diffusion of perovskite into FePd between 100 ˚C and 120˚C post-annealing. Our observations also show the interface instability of MAPbBr3/FePd and that the enhanced Kerr noise/signal ratio asserts the inter-diffusion of the perovskite into the FePd under layer upon high temperature annealing of 100-170˚C. The PL characterization data signifies a subsequent decomposition of the perovskite material during these post-annealing temperatures (100-170˚C), where the wavelength peak intensity decreased by multiples of 3 between 100 ˚C and 120˚C post-annealing.