摘要
Screen printing is a low-cost solution-based process for preparing thick-film thermoelements, which bridges the technology gap between bulk and thin-film thermoelectric devices. A screen-printed thermoelectric film on a polymer substrate may exhibit moderate flexibility but normally suffer low electrical conductivity due to the presence of porosity or organic residues. In this study, we present a current-assisted sintering process to consolidate screen-printed Bi–Sb–Te (BST) films on a polyimide substrate at the temperature below 350 °C with simultaneous passage of a pulse current of 2 × 10 3 A/cm 2 in peak current density. The electrically sintered BST film shows greatly enhanced electrical conductivity, leading to a 45% higher thermoelectric power factor (20.2 μW/cm⋅K 2 ) than the thermally sintered BST film (13.9 μW/cm⋅K 2 ). The variations of crystal defect concentration, grain size and secondary precipitates in the BST films with increasing pulse current density and sintering temperature are investigated. The influences of grain boundaries and secondary precipitates on carrier scattering behavior and thermoelectric transport properties of the BST films are also discussed.