Optimized weighted mobility induced high thermoelectric performance of ZnO‐based multilayered thin films

Abstract

As a transparent thermoelectric oxide, gallium‐doped zinc oxide (GZO) has the potential to power wearable or portable electronics and may be used in the integrated circuits industry for chip cooling. Constructing ZnO–GZO interfaces has been proposed as an effective strategy for improving thermoelectric performance of GZO thin films. However, without the aid of band structure calculation for multilayered films, it is hard to directly elucidate the underlying mechanisms of carrier transport. Weighted mobility is an indicator that reveals the inherent electronic transport properties like carrier scattering, electronic band structure, and so on. Thus, to further investigate the effects of ZnO–GZO interfaces on electrical properties of GZO thin films, the structures containing different numbers of ZnO–GZO interfaces were designed and the correlations among numbers of ZnO–GZO interfaces, weighted mobility, and electrical properties were explored. It was found that with more ZnO–GZO interfaces, the weighted mobility increased, and the power factor values also improved as well. Consequently, an enhanced power factor value reached 439 μW m−1 K−2 at 623 K. This work demonstrated the beneficial effects of multiple interfaces on the improvements of electrical transport performance through analyzing weighted mobility, which laid a foundation for further optimization of thermoelectric performance.

Enhancing Thermoelectric Performance in P‐Type Sb2Te3‐Based Compounds Through Nb─Ag Co‐Doping with Donor‐Like Effect

“…It is well known that the PF predominantly influenced by the weighted mobility ( µ w ) of the material, which is proportional to µ( m */ m e ) 3/2 , revealing that high m * and µ are conducive to improving PF . [ 34–36 ] Figure 3b depicts the µ w as a function of Nb content, which is consistent with the variation of the PF shown in Figure 3d. Ultimately, the Sb 1.97 Nb 0.03 Te 3 sample attains the highest PF values of 29.1 µW cm −1 K −2 at 323 K and 17.5 µW cm −1 K −2 at 573 K.…”

“…It is well known that the PF predominantly influenced by the weighted mobility (μ w ) of the material, which is proportional to μ(m*/m e ) 3/2 , revealing that high m* and μ are conducive to improving PF. [34][35][36] Figure 4 shows the temperature-dependent thermal conductivity and the dimensionless ZT value of the Sb 2-x Nb x Te 3 samples. In Figure 4a, the 𝜅 tot initially decreases and then increases with Nb doping mainly due to the increase in 𝜅 e and decrease in 𝜅 L .…”

Electrical Property Enhancement in Orientation‐Modulated Perovskite La‐Doped SrTiO3 Thermoelectric Thin Films

“…Due to the high-temperature endurance, chemical stability, non-toxicity, and abundance in earth, oxides are irreplaceable as thermoelectrics. [13][14][15][16][17] In n-type thermoelectrics, there were researches on ZnO, [18][19][20][21][22][23] CdO, [24] TiO 2 , [25,26] In 2 O 3 [27][28][29] -based simple oxides, and Bi 2 O 2 Se, [30,31] Bi 2 LnO 4 Cu 2 Se 2 , [32] Sr 2 MO 2 Cu 2 Se 2 (M = Co, Ni, Zn) [33] -based layered oxides, while the simple crystal structure providing few elemental sites to be tuned, and low symmetry of layered oxides resulting in low electron effective mass, [34][35][36][37][38] limited the enhancement of their electrical properties. Strontium Titanate (SrTiO 3 ) as a cubic phase perovskite oxide possesses high symmetry and high density of states near the conduction band minimum (CBM), thus having a relatively large density of states effective mass and outperforming power factors.…”