Carrier Separation Boosts Thermoelectric Performance of Flexible n‐Type Ag2Se‐Based Films

Abstract

AbstractOwing to promising room‐temperature thermoelectric properties, n‐type Ag2Se has been considered as an alternative for Bi2Te3. Herein, a carrier separation strategy is realized by compositing an insulating electron donor, polyethyleneimine (PEI), with the n‐type Ag2Se. Inhomogeneous distribution of PEI can attract the minority carriers (holes) in the n‐type Ag2Se matrix, while the separated minority carriers can avoid significant scattering of the main carriers based on coulomb repulsion, leading to record‐high carrier mobility of 1551.99 cm2 V−1 s−1 and an improved S2σ of 22.39 µW m−1 K−2 at 300 K for 6 mol% PEI/Ag2Se composite film. Moreover, with PEI acting as a binder, the resistance of 6 mol% PEI/Ag2Se composite film only increases by 6.5% after bending 1000 cycles at the radius of 6 mm, showing high stability. The assembled flexible device based on 6 mol% PEI/Ag2Se composite films exhibits an excellent power density of 73.93 W m−2 at a temperature difference of 50 K, showing potential applications in powering generation for wearable electronics.