Carrier Separation Boosts Thermoelectric Performance of Flexible <i>n</i>‐Type Ag<sub>2</sub>Se‐Based Films
Qinxue Hu, Wei‐Di Liu, Li Zhang, Han Gao, De‐Zhuang Wang, Ting Wu, Xiao‐Lei Shi, Meng Li, Qingfeng Liu, Yanling Yang, Zhi‐Gang Chen
Abstract
Abstract Owing to promising room‐temperature thermoelectric properties, n ‐type Ag 2 Se has been considered as an alternative for Bi 2 Te 3 . Herein, a carrier separation strategy is realized by compositing an insulating electron donor, polyethyleneimine (PEI), with the n ‐type Ag 2 Se. Inhomogeneous distribution of PEI can attract the minority carriers (holes) in the n ‐type Ag 2 Se 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 cm 2 V −1 s −1 and an improved S 2 σ of 22.39 µW m −1 K −2 at 300 K for 6 mol% PEI/Ag 2 Se composite film. Moreover, with PEI acting as a binder, the resistance of 6 mol% PEI/Ag 2 Se 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/Ag 2 Se 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.