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Pd2Se3 Monolayer: A Promising Two-Dimensional Thermoelectric Material with Ultralow Lattice Thermal Conductivity and High Power Factor
Chemistry of Materials ( IF 7.2 ) Pub Date : 2018-07-30 00:00:00 , DOI: 10.1021/acs.chemmater.8b01914 S. Shahab Naghavi 1 , Jiangang He 2 , Yi Xia 3 , Chris Wolverton 2
Chemistry of Materials ( IF 7.2 ) Pub Date : 2018-07-30 00:00:00 , DOI: 10.1021/acs.chemmater.8b01914 S. Shahab Naghavi 1 , Jiangang He 2 , Yi Xia 3 , Chris Wolverton 2
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A high power factor and low lattice thermal conductivity are two essential ingredients of highly efficient thermoelectric materials. Although monolayers of transition-metal dichalcogenides possess high power factors, high lattice thermal conductivities significantly impede their practical applications. Our first-principles calculations show that these two ingredients are well fulfilled in the recently synthesized Pd2Se3 monolayer, whose crystal structure is composed of [Se2]2– dimers, Se2– anions, and Pd2+ cations coordinated in a square-planar manner. Our detailed analysis of third-order interatomic force constants reveals that the anharmonicity and soft phonon modes associated with covalently bonded [Se2]2– dimers lead to ultralow lattice thermal conductivities in Pd2Se3 monolayers (1.5 and 2.9 W m–1 K–1 along the a- and b-axes at 300 K, respectively), which are comparable to those of high-performance bulk thermoelectric materials such as PbTe. Moreover, the “pudding-mold” type band structure, caused by Pd2+ (d8) cations coordinated in a square-planar crystal field, leads to high power factors in Pd2Se3 monolayers. Consequently, both electron- and hole-doped thermoelectric materials with a considerably high zT can be achieved at moderate carrier concentrations, suggesting that Pd2Se3 is a promising two-dimensional thermoelectric material. Our results suggest that hierarchical chemical bonds, that is, coexistence of different types of chemical bonds, combined with a square-planar crystal field is a promising route for designing high-efficiency thermoelectric materials.
中文翻译：
Pd 2 Se 3单层：具有超低晶格导热率和高功率因数的有希望的二维热电材料
高功率因数和低晶格导热率是高效热电材料的两个基本要素。尽管过渡金属二卤化物的单层具有高功率因数，但高晶格热导率显着阻碍了其实际应用。我们的第一性原理计算表明，这两种成分在最近合成的Pd 2 Se 3单层中都得到了很好的满足，其单晶结构由[Se 2 ] 2–二聚体，Se 2–阴离子和Pd 2+组成。阳离子以平面方式协调。我们对三阶原子间力常数的详细分析表明，与共价键结合的[Se 2 ] 2–二聚体相关的非谐和软声子模式在Pd 2 Se 3单层（1.5和2.9 W m –1 K中）导致超低晶格热导率-1沿一个-和b -axes在300 K，分别地），其比得上那些高性能块体热电材料如的PbTe。此外，由Pd 2+（d 8）阳离子在方形平面晶体场中配位，导致Pd 2 Se 3单层中的高功率因数。因此，可以在中等载流子浓度下获得具有相当高的zT的电子掺杂和空穴掺杂的热电材料，这表明Pd 2 Se 3是一种很有前途的二维热电材料。我们的结果表明，分层化学键（即不同类型化学键的共存）与方形平面晶体场相结合是设计高效热电材料的有前途的途径。
更新日期：2018-07-30
中文翻译：
Pd 2 Se 3单层：具有超低晶格导热率和高功率因数的有希望的二维热电材料
高功率因数和低晶格导热率是高效热电材料的两个基本要素。尽管过渡金属二卤化物的单层具有高功率因数，但高晶格热导率显着阻碍了其实际应用。我们的第一性原理计算表明，这两种成分在最近合成的Pd 2 Se 3单层中都得到了很好的满足，其单晶结构由[Se 2 ] 2–二聚体，Se 2–阴离子和Pd 2+组成。阳离子以平面方式协调。我们对三阶原子间力常数的详细分析表明，与共价键结合的[Se 2 ] 2–二聚体相关的非谐和软声子模式在Pd 2 Se 3单层（1.5和2.9 W m –1 K中）导致超低晶格热导率-1沿一个-和b -axes在300 K，分别地），其比得上那些高性能块体热电材料如的PbTe。此外，由Pd 2+（d 8）阳离子在方形平面晶体场中配位，导致Pd 2 Se 3单层中的高功率因数。因此，可以在中等载流子浓度下获得具有相当高的zT的电子掺杂和空穴掺杂的热电材料，这表明Pd 2 Se 3是一种很有前途的二维热电材料。我们的结果表明，分层化学键（即不同类型化学键的共存）与方形平面晶体场相结合是设计高效热电材料的有前途的途径。
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