High-Performance Ag-Se-Based n-Type Printed Thermoelectric Materials for High Power Density Folded Generators

High-performance Ag-Se-based n-type printed thermoelectric (TE) materials suitable for room-temperature applications have been developed through a new and facile synthesis approach. A high magnitude of the Seebeck coefficient up to 220 mu V K-1 and a TE power factor larger than 500 mu W m(-1) K-2 for an n-type printed film are achieved. A high figure-of-merit ZT similar to 0.6 for a printed material has been found in the film with a low in-plane thermal conductivity kappa(F) of similar to 0.30 W m(-1) K-1. Using this material for n-type legs, a flexible folded TE generator (flexTEG) of 13 thermocouples has been fabricated. The open-circuit voltage of the flexTEG for temperature differences of Delta T = 30 and 110 K is found to be 71.1 and 181.4 mV, respectively. Consequently, very high maximum output power densities p(max) of 6.6 and 321 mu W cm(-2) are estimated for the temperature difference of Delta T = 30 K and Delta T = 110 K, respectively. The flexTEG has been demonstrated by wearing it on the lower wrist, which resulted in an output voltage of similar to 72.2 mV for Delta T approximate to 30 K. Our results pave the way for widespread use in wearable devices.