缺陷在二維混合有機無機鹵化物鉛鈣鈦礦中的影響

Abstract

在本研究中，我們成功利用配體輔助再沉澱法 (ligand-assisted reprecipitation method, LARP 在 室 溫條件下 （（< 合成了二維 層狀 有機無機鈣鈦礦奈米片 。透過引入短碳鏈乙二胺陽離子作為橋接配體，控制了合成溫度和反溶劑比例，從而優化奈米片的生長 。使用穿透式電子顯微鏡與高解析粉末 X光繞射鑑定二維形貌與晶體結構 此鈣鈦礦半導體之層間距小於 1 nm (約 0.8 Å 與先前其他實驗室用以二胺合成之樣品更 具有強烈的量子侷限效應。其中透 螢光光譜發現低溫合成之樣品具有 (390 nm) 和 (500 nm) 兩組 螢光推測低溫樣品具有表現出出色的光學性質 ，並展 現出紫外至可見光範圍（ 320 nm）的吸收和發射特性，以及約 3.7 eV的高帶隙，源於量子和介電限制 ，及 為提高材料穩定性，我們採用聚甲基丙烯酸甲酯（ PMMA）進行了鈍化，包括共沉澱法和後修飾法。不僅提升了奈米片在氮氣和氧氣環境下的光學性能，而 且通過穿透式電子顯微鏡 、 螢光光譜、疏水性 確認了 PMMA鈍化 奈米片 表面缺陷的 形貌。此外，比較了乾燥箱與手套箱 及大氣下備樣與 氮 氣 環境下備樣 以及不同存放時間 氧氣 對樣品晶格的影響。低溫合成之 樣品 出色的光學性質期待應用於 LED應用而高溫合成之樣品。高溫合成之樣品不發光的特性 未來將聚焦於進一步的光電流研究，探索其在光電應用中的潛力。 最後發現共沉澱法具有鈍化晶體內的缺陷能力同時也能鈍化晶體表面的缺陷，而後修飾法鈍化晶體表現的能力更為出色。

In this study, we successfully synthesized two-dimensional layered organic-inorganic perovskite nanosheets at room temperature (<100°C) using the ligand-assisted reprecipitation method (LARP). By introducing short-chain ethylenediamine cations as bridging ligands, we controlled the synthesis temperature and antisolvent ratio to optimize the growth of the nanosheets. The two-dimensional morphology and crystal structure were characterized using transmission electron microscopy and high-resolution powder X-ray diffraction. The perovskite semiconductors demonstrated an interlayer spacing of less than 1 nm (approximately 0.8Å), exhibiting stronger quantum confinement effects compared to samples synthesized with diamines in other laboratories. Photoluminescence spectroscopy revealed two fluorescence groups at 390 nm and 500 nm in samples synthesized at low temperatures, indicating exceptional optical properties with absorption and emission characteristics ranging from UV to visible light (320 nm) and a high bandgap of about 3.7 eV due to quantum and dielectric confinement. To enhance material stability, we utilized polymethyl methacrylate (PMMA) for passivation using both coprecipitation and post-modification methods. This not only improved the optical performance of the nanosheets in nitrogen and oxygen environments but also confirmed the morphology of PMMA-passivated surface defects through transmission electron microscopy, fluorescence spectroscopy, and hydrophobicity tests. Additionally, we compared the effects of oxygen on the lattice of the samples prepared under atmospheric and nitrogen conditions in a dry box and glove box over different storage durations. The outstanding optical properties of the low-temperature synthesized samples hold promise for LED applications, while the non-luminescent characteristics of the high-temperature synthesized samples will focus on further photoelectric current research to explore their potential in photonic applications. Finally, it was found that the coprecipitation method could passivate both internal and surface defects of the crystals, whereas the post-modification method showed superior ability to passivate the crystal defects.