Current State‐of‐the‐Art in the Interface/Surface Modification of Thermoelectric Materials

Abstract

Thermoelectric (TE) materials are prominent candidates for energy converting applications due to their excellent performance and reliability. Extensive efforts for improving their efficiency in single‐/multi‐phase composites comprising nano/micro‐scale second phases are being made. The artificial decoration of second phases into the thermoelectric matrix in multi‐phase composites, which is distinguished from the second‐phase precipitation occurring during the thermally equilibrated synthesis of TE materials, can effectively enhance their performance. Theoretically, the interfacial manipulation of phase boundaries can be extended to a wide range of materials. High interface densities decrease thermal conductivity when nano/micro‐scale grain boundaries are obtained and certain electronic structure modifications may increase the power factor of TE materials. Based on the distribution of second phases on the interface boundaries, the strategies can be divided into discontinuous and continuous interfacial modifications. The discontinuous interfacial modifications section in this review discusses five parts chosen according to their dispersion forms, including metals, oxides, semiconductors, carbonic compounds, and MXenes. Alternatively, gas‐ and solution‐phase process techniques are adopted for realizing continuous surface changes, like the core–shell structure. This review offers a detailed analysis of the current state‐of‐the‐art in the field, while identifying possibilities and obstacles for improving the performance of TE materials.

Enhanced Thermoelectric Performance of GeTe-Based Composites Incorporated with Fe Nanoparticles

“…The interface modification method, such as incorporating metallic nanoinclusions into the TE matrix, is commonly utilized to enhance PF and reduce κ L . Nonmagnetic metallic inclusions (Cu, , Ag, Au, and Bi) with different work functions (4.22–5.10 eV) in Bi 2 Te 3 , or FeSb 2 system can usually form a potential barrier or promote the electronic transport to effectively adjust the thermoelectric properties.…”

“…24 Constructing suitable nanostructures to optimize the electronic and thermal transport properties simultaneously is widely used in the GeTe-based system, such as superlattices, 25,26 stacking faults, 27 dislocation arrays, 28 in situ nanoprecipitates, 9,29 and ex situ nanophases. 30−32 The interface modification method, 33 such as incorporating metallic nanoinclusions into the TE matrix, is commonly utilized to enhance PF and reduce κ L . Nonmagnetic metallic inclusions (Cu, 34,35 Ag, 36 Au, 35 and Bi 37 ) with different work functions (4.22−5.10 eV) in Bi 2 Te 3 35,37 or FeSb 2 34 system can usually form a potential barrier or promote the electronic transport to effectively adjust the thermoelectric properties.…”

Improving the thermoelectric performance of ZrNi(In,Sb)-based double half-Heusler compounds

“…5 Thus, good TE materials require high power factors (PF = S 2 ρ −1 ) as well as low total thermal conductivity to realize high zT . 6 However, optimizing the zT is challenging due to the intercorrelation of the transport parameters ( S , ρ , and κ ele ), such as via the carrier concentration. 7 To realize effective decoupling, tremendous efforts are devoted, which can generally be categorized into two approaches.…”

Effect of Powder ALD Interface Modification on the Thermoelectric Performance of Bismuth

“…[26] This goal is achieved by deflecting the electron bands at the interfaces between the second phase and the bulk matrix, allowing electrons with high energy to pass while scattering the low-energy electrons. [27] Selective scattering increases the value of S. Additionally, it should be noted that the method of incorporating or coating the second phase differs significantly from nanoprecipitation during the synthesis process in traditional systems, such as PbTe [28,29] and AgSbTe 2 , [30,31] so that the composition of the second phase and its distribution are more controlled and uniform compared to precipitation.…”