Room-Temperature Welding of Silver Telluride Nanowires for High-Performance Thermoelectric Film

Flexible thermoelectric materials that can harvest waste heat energy have attracted great attention because of the rapid progress of flexible electronics. Ag2Te nanowires (Ag2Te NWs) are considered as promising thermoelectric materials to fabricate flexible thermoelectric film and device because of their high Seebeck coefficient, but poor contact between the Ag2Te NWs results in low electrical conductivity. Generally, hot or cold pressing can increase the electrical conductivity between the Ag2Te NWs. However, these process tend to destroy the initial morphology of the Ag2Te NWs and/or cause only physical contact between the Ag2Te NWs. Herein, we report an approach to the room-temperature welding of Ag2Te NWs to enhance their contacts by facile combination of vacuum filtration and drop-coating methods. The obtained Ag2Te NWs film exhibits excellent Seebeck coefficient of -99.48 μV/K and high electrical conductivity of 15 335.05 S/m at room temperature, which gives the power factor of 151.76 μW m-1 K-2. Surprisingly, an optimal Seebeck coefficient of -154.96 μV/K and electrical conductivity of 14 982.42 S/m can be obtained at 420 K, giving a power factor of 359.76 μW m-1 K-2. Moreover, the electrical resistance of the Ag2Te NWs film was only 1.3 times of the initial electrical resistance after 1000 bending cycles, indicating good flexibility of the film. A finger-touch test is conducted by using the Ag2Te NWs film as thermoelectric power generator, which achieves a stable output voltage of about 0.52 mV, suggesting its great potential applications in self-powered flexible electronic devices.