Al-Doped Zinc Oxide Nanocomposites with Enhanced Thermoelectric Properties

Abstract

ZnO is a promising high figure-of-merit (ZT) thermoelectric material for power harvesting from heat due to its high melting point, high electrical conductivity σ, and Seebeck coefficient α, but its practical use is limited by a high lattice thermal conductivity κ(L). Here, we report Al-containing ZnO nanocomposites with up to a factor of 20 lower κ(L) than non-nanostructured ZnO, while retaining bulklike α and σ. We show that enhanced phonon scattering promoted by Al-induced grain refinement and ZnAl(2)O(4) nanoprecipitates presages ultralow κ ∼ 2 Wm( -1) K(-1) at 1000 K. The high α∼ -300 μV K(-1) and high σ ∼ 1-10(4) Ω(-1 )m(-1) result from an offsetting of the nanostructuring-induced mobility decrease by high, and nondegenerate, carrier concentrations obtained via excitation from shallow Al donor states. The resultant ZT ∼ 0.44 at 1000 K is 50% higher than that for the best non-nanostructured counterpart material at the same temperature and holds promise for engineering advanced oxide-based high-ZT thermoelectrics for applications.

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

“…Material family References Mn oxide [49][50][51][52][53][54][55][56][57][58][59][60] ZnO, SrTiO 3 33, [61][62][63][64][65][66][67][68][69][70][71][72] Co oxide 34,35,[73][74][75][76][77] other oxide 28,63,[78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96] Si-Ge …”

Metal oxides for thermoelectric power generation and beyond

“…It is a nontoxic, low-cost, and earth-abundant material which is stable at a high temperature. These properties make it a promising candidate for n-type TE materials for energy harvesting in hightemperature applications [88][89][90] ), due to the high crystal quality resulting in a large Seebeck coefficient (~478 μV/K) [91]. Figure 6 presents the temperature-dependent PF of ZnObased TE materials.…”

Electrothermal phenomena in zinc oxide nanowires and contacts

“…Recent research has examined their potential in energy applications including thermoelectric waste heat recovery [6,7], solar cells [8], and batteries [9][10][11]. Zinc oxide nanostructures have generated particular interest due to their optical and electrical properties, ease of synthesis, and non-toxicity [12][13][14]. Most ZnO nanowire devices use electrical contacts where the contact composition and transport of energy carriers are critical for performance [15].…”