Effect of dopants and nanostructuring on the thermoelectric properties of ZnO materials

Abstract

Zinc oxides have attracted attention in high-temperature waste heat recovery due to their high melting points. This review aims to provide a comprehensive summary of the effects of dopant on thermoelectric properties of ZnO based bulk, thin films, nanowire as well as the effects of nanostructuring on ZnO based materials. In general, the thermoelectric performance can be enhanced by a single doping. Among single dopant elements, Al dopant seems to be effective dopant resulting in better thermoelectric properties. However, the solubility limit of the dopant in single doping limits the improvement of thermoelectric performance. Efforts in dual doping to improve the thermoelectric properties of ZnO materials have been conducted. As a result, the drastic improvement of the thermoelectric performance from Al-Ga dually doped ZnO bulk and Ga-In dually doped ZnO thin films shows strong evidence of this approach. In addition to doping effects, the thermoelectric performance can also be enhanced through structural effects such as mismatches between the film and substrate, morphology, thermal treatments or introducing nano-precipitated materials. In addition, the low-dimensional structure such as nanowire structure is promising for improving the thermoelectric properties of materials because of their strong quantum confinement effect. This leads to the increase of the Seebeck coefficient according to the Mott's relationship without lowering the electrical conductivity.

Indium Dopant Concentration Effects on Zinc Oxide Nanowires

“…ZnO based on its superior conducting properties is frequently doped with various elements from group III, IV, or V such as Ga, Al, In, Sb, Sn, and so on to enhance its electrical and optical properties further. , Doping with selective elements offer an alternate route to manipulate electrical, optical, and magnetic properties of materials in an effective way. Doping that involves intentional incorporation of atoms into host lattice or adding ions of specific elements to generate materials of desired properties is a key for building functional nanostructures and devices .…”

Progress and challenges of emerging MXene based materials for thermoelectric applications

“…ZnO is another potential candidate for thermoelectric energy conversion owing to its high abundance, low cost, nontoxicity, and thermal stability. 193 , 194 , 195 , 196 , 197 , 198 However, pristine ZnO usually supplies a low electrical conductivity because of the low carrier concentration, limiting its thermoelectric application. Compositing with 2D materials is considered to be a feasible route to increasing the carrier concentration, thus improving the electrical conductivity.…”

Thermoelectric properties of Pnma and R3m GeS and GeSe

“…A wide variety of inorganic materials have been explored as thermoelectric (TE) materials, including chalcogenides, [10][11][12][13][14] metal oxides, [15][16][17][18] clathrates, [19][20][21][22] and skutterudites. [23][24][25][26] The current industry-standard TEs are Bi 2 Te 3 (ZT max E 1 from 359-450 K) and PbTe (ZT max = 2.2 at 915 K).…”