High Transverse Thermoelectric Performance and Interfacial Stability of Co/Bi_0.5Sb_1.5Te₃ Artificially Tilted Multilayer Thermoelectric Devices

Abstract

Artificially tilted multilayer thermoelectric devices (ATMTDs) have attracted extensive attention because of their numerous advantages, such as high integration, great structural freedom, and large transverse Seebeck coefficients. ATMTDs are composed of numerous alternating stackings of two types of materials with large differences in electrical and thermal transport. Therefore, it is of great interest to find ATMTDs with both high transverse thermoelectric performance and good interfacial stability to develop their practical application. In this work, cobalt (Co) and Bi 0.5 Sb 1.5 Te 3 (BST) are chosen to prepare Co/BST ATMTDs. The interfacial structure and composition of Co/BST are characterized, and its interfacial stability and transverse thermoelectric performance are evaluated. The results show that the thickness of the Co/BST interfacial reaction layer is about 4 μm. Annealing at 473 K for 32 h does not increase the thickness, which indicates better interfacial stability than Ni/BST. After structure optimization, Co/BST ATMTD has ZT zx = 0.41, which is second only to YbAl 3 /BST ATMTDs. Meanwhile, the transverse Seebeck coefficient reaches −120.38 μV/K. The outstanding interfacial stability and transverse thermoelectric performance promise excellent thermal response and refrigeration performance with Co/BST ATMTDs.

Hybrid Transverse Magneto‐Thermoelectric Cooling in Artificially Tilted Multilayers

“…In this structure, anisotropic conduction of electrons and holes results in the finite off-diagonal terms of the thermoelectric transport tensor, making the multilayer into a transverse thermoelectric converter. [18][19][20][21][22][23][24][25][26][27] In other words, transverse thermoelectric conversion in the artificially tilted multilayer originates from the anisotropic structure itself, and is driven by the longitudinal Seebeck/Peltier effect. This process occurs to the maximum degree when one of the constituent materials is a p-type thermoelectric material and the other is an n-type material but occurs even with the same carrier type when the magnitude of the Seebeck/Peltier coefficient is different from each other.…”

“…Transverse thermoelectric generation using such multilayers has been studied for many years, and the transverse thermopower and figure of merit can be designed by selecting appropriate constituent materials and optimizing the tilt angle and device geometry. [18][19][20][21][22][23][24][25][26][27] Transverse thermoelectric conversion has been demonstrated in not only macroscale bulk materials but also nanoscale superlattices with tilted structures, which are often referred to as (p × n)-type multilayers, [34,35] although we focus only on bulk stacks in this study. However, the contributions of the magneto-thermoelectric effects in artificially tilted multilayers have not been investigated.…”

“…The transverse thermopower due to structure-induced ODPE, 𝜎 xx , and 𝜅 zz can be calculated analytically using equations in the literature. [18][19][20][21][22][23][24][25][26][27] The contributions of MPE and the electrical and thermal magnetoresistances can be introduced as the field dependence of the transport coefficients in the equations for determining the ODPEdriven transverse thermopower, 𝜎 xx , and 𝜅 zz . However, in our artificially tilted multilayers, S T includes not only the structureinduced ODPE and MPE contributions but also the OEE contribution.…”

“…[3] The former phenomena include the ordinary and anomalous Nernst/Ettingshausen effects [4][5][6][7][8][9][10][11][12] and goniopolarity, [13] while the latter includes the spin Seebeck/Peltier effect [14][15][16] and Seebeck/Peltier-driven transverse thermoelectric conversion in magnetic/thermoelectric hybrid materials [17] and in artificially tilted multilayers. [18][19][20][21][22][23][24][25][26][27] As typified by the Nernst/Ettingshausen effects, most transverse thermoelectric effects appear in conductors under external magnetic fields or in magnetic materials with spontaneous magnetization, and these effects have been actively investigated in Figure 1. LIT measurements of thermoelectric effects in an artificially tilted multilayer.…”

Enhancement of Thermoelectric Properties of p-Type Bi0.4Sb1.6Te3 Incorporated by BaFe12O19 Magnetic Nanoparticles

“…Unfortunately, their relatively low ZT values have limited their extensive use. Recent studies have focused on optimization strategies that have been adopted to improve the thermoelectric performance, including carrier filtering engineering, band engineering, high-entropy engineering, , and phonon scattering engineering in applications, such as hierarchical microstructures, lattice anharmonicity, and magnetic particles scattering. ,− …”