Adding boron nitride or SiO2/MnO/graphene composite to a flexible thermoelectric generator to change its operation mode to temperature sensor

This work reports AgSe/SbTe-based thermoelectric (THME) devices and their use as temperature sensors. The AgSe//SbTe-THME device produced an open-circuit-voltage (V O ) of 32 mV, a power density (P D ) of 100 nW cm -2 and an absolute seebeck-coeficient of 320 μV K -1 in range of 40–100 °C. Later, the AgSe electrode was replaced with AgSe+Boron nitride (BN) electrode, creating a (AgSe+BN)//SbTe-THME device. The SbTe electrode was also replaced by SbTe+SiO 2 /MnO/Graphene electrode, and this device was named as AgSe//(SbTe+MnO)-THME. We obtained V O values (at of 40–100 °C) of 480 mV and 520 mV for the (AgSe+BN)//SbTe-THME and AgSe//(SbTe+MnO)-THME devices, respectively. Those values are 14-15 times higher with respect to the AgSe//SbTe-THME device. The highest power/Seebeck coefficient of 0.9 μW cm -2 /5.21 mV K -1 was obtained for the AgSe//(SbTe+MnO)-THME device. The devices above with BN and MnO were also evaluated as temperature sensors (TS) and the lowest response time (Res) of 12.88 s and the highest sensitivity (TCR) of 2.92 % °C -1 were obtained from the (AgSe+BN)//SbTe-TS sensor. Raman and UV-Vis techniques demonstrated that decreasing the content of defects on the electrodes increased the voltages generated by the THME devices and decreased the response times of the sensors. XPS demonstrated that the chemical stability is maintained only in the electrodes of the (AgSe+BN)//SbTe-TS devices despite the increase of temperature, therefore, they increased their sensitivity for the detection of temperature at higher temperatures. The dual devices with thermoelectric and temperature-sensor functions were fabricated on recycled plastics, which reduced considerably their cost. • A dual function device: Thermoelectric (THME) and temperature sensor was fabricated on recycled plastics • Outstanding Seebeck coeficients of 2-6.5 mV K -1 were obtained from flexible thermoelectric devices • Adding MnO to the Ag 2 Se based THME device produced the highest voltage of 521 mV • AgSe//(SbTe+MnO) cell worked as temperature sensors and had response-time of 13.19 s at 50 °C • (AgSe+BN)//SbTe THME device produced a voltage of 481 mV and response-time of=12.88 s at 90 °C