High-performance flexible Bi₂Te₃ films based wearable thermoelectric generator for energy harvesting

The development of wearable thermoelectric generator for human energy harvesting has attracted significant interests in recent years. However, the thermoelectric properties and flexibility of inorganic thermoelectric films still need to be improved. In this study, high-performance flexible Bi₂Te₃ films with controlled microstructure are prepared on the flexible polyimide substrate by regulating the sputtering pressures, and the power factor can reach 21.7 μW cm⁻¹ K⁻². By coating poly (dimethylsiloxane) on the Bi₂Te₃ surface, the flexibility of the films is improved significantly, so that the change of resistance is kept below 5% after bending 2000 cycles at the radius of 7 mm. Then an in-plane thermoelectric generator containing 13 pairs of thermocouples is fabricated with the open circuit voltage of 48.9 mV and the output power of 693.5 nW at ΔT = 24 K. Meanwhile, the transient open circuit voltage of 12.99 mV is achieved when using the temperature difference between the ambient air and the body, indicating promising application for human energy harvesting.