Screen-printed flexible thermoelectric generator with directional heat collection design

A thermoelectric generator (TEG) was fabricated on a flexible substrate by screen printing and pressured sintering techniques for low-temperature heat harvesting applications. The screen-printed Bi-Sb-Te (p-type) and Bi-Se-Te (n-type) films that are sintered at 345 °C under a pressure of 25 MPa show the respective thermoelectric power factor of 14.3 and 8.4 μW/cm⋅K2 at room temperature. A planar TEG made of three pairs of Bi-Sb-Te and Bi-Se-Te thermoelements delivers an output power of 50 μW at a temperature difference of 54.9 °C. The flexible TEG shows no electrical degradation after 1000 cycles of bending in the longitudinal and transverse directions of the thermoelements. A directional heat collection design is proposed to maximize the heat supply area of planar TEGs. The fabricated TEG can attain a maximum output power density of 58.3 μW/cm2 under a temperature difference of 5.7 °C with a graphite heat transmission layer attached to a heat source at the temperature of 39.8 °C. It can serve as a self-sustained power source for wearable electronics and sensing devices by harvesting thermal energy from environment or human body. •A μ-watt flexible thermoelectric generator is made by screen-printing technology.•Thermoelectric power factors of printed films are enhanced by pressured sintering.•The planar TEG shows no electrical degradation after 1000 bending cycles.•A heat transmission layer is implemented to raise TEG heat collection capacity.