Fabrication and Optimization of Brush-Printed n-type Bi2Te3 Thick Films for Thermoelectric Cooling Devices

Abstract

A simple, efficient and rapid brush-printing method has been developed for preparation of n-type Bi2Te2.7Se0.3 films approximately 100–150 μm thick. X-ray diffraction, scanning electron microscopy, electron probe microanalysis, and four-point probe measurements were used to characterize the crystal structure, composition, microstructure, and electrical properties of the films. The results showed that all the n-type Bi2Te2.7Se0.3 thick films were composed of single-phase Bi2Te2.7Se0.3; the grains in the films were randomly distributed in the low-temperature-annealed samples and predominantly oriented along the (00l) plane in samples annealed at temperatures >673 K. σ and the absolute value of α first increased substantially with increasing the annealing temperature in the range 573–673 K then decreased when the annealing temperature was increased further. The dependence of σ and α on annealing temperature may be reasonably explained on the basis of the change in the microstructure induced by annealing. The performance of a prototype cooling device containing n-type Bi2Te2.7Se0.3 thick films was evaluated for temperature differences produced by use of different DC currents.