Abstract In this study, we, for the first time, introduce p-type two-dimensional (2D) WSe2 nanoinclusions in n-type Pb/I co-doped SnSe matrix to form WSe2/SnSe p-n junctions. These p-n junctions act as energy barriers and effective phonon scattering sources, leading to a high figure-of-merit (ZT) of ∼1.35 at ∼790 K in n-type polycrystalline SnSe. First-principles density functional theory calculation results indicates that I-doping shifts Fermi level up into conduction bands of SnSe, making the system n-type behavior, while both Pb and I dopants act as point-defect-based short-wavelength phonon scattering centers. The introduced p-type 2D WSe2 nanoinclusions induce high-density WSe2/SnSe interfaces that act as p-n junctions, which block the electron carriers and rationally tune the carrier density, contributing to a high absolute Seebeck coefficient of ∼470.7 μV K−1 and a high power factor of ∼5.9 μW cm−1 K−2. Meanwhile, the dense phase boundaries and considerable lattice strains by the introduced 2D WSe2 nanoinclusions significantly strengthen the mid- and long-wavelength phonon scattering, giving rise to a much low thermal conductivity of 0.35 W m−1 K−1 and in turn a high ZT of ∼1.35. This study provides a new strategy to achieve high thermoelectric performance in n-type polycrystalline SnSe.

中文翻译：

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二维 WSe2/SnSe pn 结确保 n 型 Pb/I 共掺杂多晶 SnSe 中的超高热电性能

摘要 在本研究中，我们首次在 n 型 Pb/I 共掺杂 SnSe 基体中引入 p 型二维 (2D) WSe2 纳米夹杂物，以形成 WSe2/SnSe pn 结。这些 pn 结充当能量势垒和有效的声子散射源，导致在 n 型多晶 SnSe 中在 ~790 K 下具有 ~1.35 的高品质因数 (ZT)。第一性原理密度泛函理论计算结果表明，I 掺杂将费米能级向上移动到 SnSe 的导带，使系统具有 n 型行为，而 Pb 和 I 掺杂剂均充当基于点缺陷的短波声子散射中心. 引入的 p 型 2D WSe2 纳米夹杂物诱导高密度 WSe2/SnSe 界面，充当 pn 结，阻挡电子载流子并合理调整载流子密度，有助于实现 ~470.7 μV K-1 的高绝对塞贝克系数和 ~5.9 μW cm-1 K-2 的高功率因数。同时，引入的 2D WSe2 纳米夹杂物形成的致密相界和相当大的晶格应变显着增强了中波长和长波长声子散射，从而产生了 0.35 W m-1 K-1 的低热导率，进而产生了高ZT 约为 1.35。该研究为在 n 型多晶 SnSe 中实现高热电性能提供了一种新策略。