Copper-doped single-phase nanosheets (NSs) of rhombohedral Cu_xBi₂Se₃, x = 0, 0.05, 0.10, and 0.15 with the space group R3̅m of crystallite size in the range of 36–43 nm and an average thickness of 41 nm have been synthesized successfully in a modified polyol method using diethylene glycol (DEG) alone. Thermoelectric (TE) properties of these samples have been reported here. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman study show that Cu intercalates into the Bi₂Se₃ lattice. Notably, a large negative Seebeck coefficient with a relatively low electrical resistivity indicates their n-type semiconducting nature with low energy charge filtering in the electrical transport. A 330% enhancement in the TE figure of merit (ZT) at 300 K for x = 0.15 compared to that of x = 0 is observed due to the intercalation of Cu between quintuples and energy filtering of carriers at grain boundaries (GBs), showing a good potential of this approach. Therefore, the Cu-intercalation approach to enhance ZT has the potential to pave the way for the future development of more efficient Bi₂Se₃-based TE materials that can operate effectively near room temperature.

中文翻译：

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铜插层对多元醇法制备的 CuxBi2Se3（x = 0、0.05、0.10 和 0.15 纳米片）热电性能的影响

菱形 Cu _x Bi ₂ Se ₃的铜掺杂单相纳米片 (NSs) ，x = 0、0.05、0.10 和 0.15，空间群R 3̅ m的微晶尺寸在 36–43 nm 范围内，平均尺寸为仅使用二甘醇（DEG），通过改进的多元醇方法成功合成了厚度为 41 nm 的薄膜。此处报告了这些样品的热电 (TE) 特性。X 射线衍射 (XRD)、X 射线光电子能谱 (XPS) 和拉曼研究表明 Cu 嵌入 Bi ₂ Se _3中格子。值得注意的是，大的负塞贝克系数和相对较低的电阻率表明它们具有 n 型半导体性质，在电传输中具有低能电荷过滤。与x = 0 相比，在 300 K 时， x = 0.15时的 TE 品质因数 ( ZT )比x = 0 时提高了 330%，这是由于五元组之间插入了 Cu 以及晶界 (GB) 处载流子的能量过滤，这表明这种方法的良好潜力。因此，提高ZT的Cu插层方法有可能为未来开发更高效的Bi ₂ Se ₃基TE材料铺平道路，这些材料可以在室温附近有效运行。