Ultraflexible and High-Thermoelectric-Performance Sulfur-Doped Ag 2 Se Film on Nylon for Power Generators.

In this work, we developed a facile method to fabricate low-cost, flexible, and high-thermoelectric-performance n-type Ag 2 Se 1- x S x @(Ag 2 S 1- y Se y /S) composite film on a nylon membrane. The composite film was prepared by first performing wet-chemical synthesis of the S-doped Ag 2 Se powder, then vacuum-assisted filtration of the powder on a nylon membrane, and finally hot-pressing. Transmission electron microscopy (TEM) observation and energy-dispersive system (EDS) analysis of the film revealed that the film had a porous network-like microstructure, in which Ag 2 Se 1- x S x sub-micron grains formed the skeleton and are coated by a ∼15 nm thick layer of S-rich Ag 2 S 1- y Se y nanograins mixed with an S amorphous phase. The film showed a power factor of ∼954.7 μW·m -1 ·K -2 at 300 K and superior flexibility (94.4% of the original electrical conductivity was preserved after bending 2000 times around a rod with a radius of 4 mm). Moreover, a six-leg flexible thermoelectric generator was assembled with the film and produced a maximum power of 6.67 μW (corresponding power density ∼14.8 W/m 2 ) at a temperature difference of 38.7 K. This work reveals a novel approach to explore high-performance and low-cost flexible thermoelectric devices suitable for room-temperature applications.