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 materials suitable for room temperature applications have been developed through a new and facile synthesis approach. A high magnitude of Seebeck coefficient up to 220 muVK(-1) and a thermoelectric power factor larger than 500 muWm(-1)K(-2) for an n-type printed film is achieved. A high figure-of-merit ZT 0.6 for a printed material has been found in the film with a low in-plane thermal conductivity, kappaF of 0.30 Wm(-1)K(-1). Using this material for n-type legs, a flexible-folded thermoelectric generator (flexTEG) of 13 thermocouples has been fabricated. The open-circuit voltage of the flexTEG for temperature differences of T=30 K and 110 K are found to be 71.1 and 181.4 mV respectively. Consequently, very high maximum output power densities pmax of 6.6 microWcm(-2) and 321 microWcm(-2) is estimated for temperature difference of =30 K and =110 K respectively. The flexTEG has been demonstrated by wearing it on the lower wrist, which resulted in an output voltage of 72.2 mV for T30 K. Our results pave the way for a widespread use in wearable devices.