Significant Improvement in Thermoelectric Performance of AgInSe₂-Based Composites through In Situ Formation of Ag₂Se

Abstract

As the development of n-type ternary chalcopyrite semiconductors in thermoelectrics (TEs) is relatively slow compared to that of their p-type counterparts, it greatly restricts the fabrication of their modules and real applications. In this work, we prepare n-type AgInSe2-based composites via mixing with their electrical property-counter Ag2Se, where each species plays a role in improving the TE performance. The results confirm that the presence of the minor Ag2Se enhances the Hall carrier concentration (n H) significantly and thereby improves the electrical property of the system. At the same time, it reduces the lattice thermal conductivity (κL) at low temperatures as the phonon scattering in the AgInSe2/Ag2Se heterointerface increases. On another note, the internal lattice distortion (ψ) in the main phase AgInSe2 strengthens as the content of Ag2Se increases, which reduces the κL significantly at high temperatures. As a consequence, the resultant ZT value reaches ∼0.9 at 846 K, about 2.7 times that of the pristine AgInSe2.

Thermoelectric Silver‐Based Chalcogenides

“…In order to utilize the intrinsic properties of Ag 2 Se, Zhong et al prepared a AgInSe 2 ‐based hybrid comprising a AgInSe 2 primary phase and a Ag 2 Se secondary phase, Ag 1+2 x InSe 2+ x ( x = 0−0.4). [ 127 ] The in situ formation of Ag 2 Se species in the AgInSe 2 matrix played the dual role of enhancing the carrier concentration/electrical properties, as well as promoting phonon scattering at the Ag 2 Se/AgInSe 2 heterointerfaces (i.e., atomic scale lattice distortion and phase interfaces), thereby reducing the lattice thermal conductivity of the hybrid. Consequently, a zT value of ≈0.9 was reached at 846 K, a 2.7 times enhancement in thermoelectric performance compared to pristine AgInSe 2 ( Figure 9 a–d ).…”

“…An inset in (c) is the total thermal conductivity. Reproduced with permission [127]. Copyright 2020, American Chemical Society.…”

Recent advances in designing thermoelectric materials

“…2 shows the maximum ZT achieved for bulk thermoelectric materials over the past six years as a function of temperature. 33–234…”

Structure and thermoelectric performance of Ag_<i>y</i>In_{3.33–<i>y</i>/3}Se₅ compounds

“…材料的载流子热导率可以通过经典的Wiedemann- [35] , AgInTe 2 [38] , AgIn 5 Se 8 [30] 和 CuInSe 2 [39] 等, 且在平行于烧结压力方向上样品的晶 格热导率均低于垂直于烧结压力方向. 如沿着平行 烧结压力方向, y = 0.384样品室温时的晶格热导率…”

“…AgInTe 2 [38] , AgIn 5 Se 8 [30] 和CuInSe 2 [39] 的晶格热导率; (c) Ag y In 3.33-y/3 Se 5 , AgInSe 2 [35] , AgIn 5 Se 8 [30] , Ag 1.03 In 5 Se 8 [30] , Ag 0.9 Cd 0.1 InSe 8 [35] ,…”