Scalable printing high-performance and self-healable Ag2Se/terpineol nanocomposite film for flexible thermoelectric device

Flexible thermoelectric (TE) generators (f-TEGs) are promising candidates to power explosively growing wearable electronics by continually converting body heat into electricity. However, intrinsic brittleness, unscalability, and high costs hinder high-performance bulk TE materials from application as f-TEGs. Herein, we report a flexible and self-healable Ag2Se/terpineol composite film on a nylon membrane prepared by first one-pot synthesis of Ag2Se powder, then screen-printing, and finally low-temperature (473 K) heat treatment. Microstructure observations reveal that the film is dense and that it consists of nano to micron Ag2Se grains with coherent- and semicoherent grain boundaries and a very small amount of terpineol at nanopores and/or grain boundaries. Because of the unique microstructure and synergistic effect of the two components, an optimal film exhibits a high power factor of 1550 μW m-1 K-2 (corresponding zT ∼ 0.8) at room temperature and good mechanical properties (flexibility, anti-tensile property, and self-healing ability). A six-leg f-TEG assembled with the film shows a power density of 16.23 W m-2 at a temperature difference of 34.1 K and excellent flexibility.