2025/11/10 by Althaf RajaMohamed, Hyoung-Won Son, Takao Mori +1
Materials Science · Engineering · #Advanced Thermoelectric Materials and Devices #ZnO doping and properties #Nanomaterials and Printing Technologies
paper · doi:10.48505/nims.5871
Band structure engineering is an effective way to improve the Seebeck coefficient without affecting the electrical conductivity. This study Al 3s state hybridized with Zn 4s state shifts the Fermi level inside the conduction band in Al, Sn codoped ZnO exposing its metallic behavior. Sn impurity creates large density of states near Fermi level leading to high Seebeck coefficient. In this material, in addition to scattering of low-frequency phonons by interfaces and of high-frequency phonons by point defects, scattering of mid-frequency phonons by dense dislocations, localized at the grain boundaries, has been an effective strategy to reduce the lattice thermal conductivity. Dual doping creates low angle grain boundaries composed of dislocation arrays with a misorientation less than about 13.5°. These dislocation arrays along with lattice strain significantly reduce the thermal conductivity to 6.391 W m-1K-1 at room temperature in Zn0.97Al0.02Sn0.01O. All these effects lead to a high figure of merit ZT of 0.61 at 997 K. A single leg thermoelement fabricated using Zn0.97Al0.02Sn0.01O shows an open circuit voltage of 122 mV with DT at 500K.