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

• Published in: Advanced energy materials Vol. 14; no. 36
• Main Authors: Hu, Qin‐Xue, Liu, Wei‐Di, Zhang, Li, Gao, Han, Wang, De‐Zhuang, Wu, Ting, Shi, Xiao‐Lei, Li, Meng, Liu, Qing‐Feng, Yang, Yan‐Ling, Chen, Zhi‐Gang
• Format: Journal Article
• Language: English
• Published: 26.09.2024
• Subjects: Ag2Se; flexible; insulating electron donor; thermoelectric
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202401890

Owing 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. The insulating electron donor induces carrier separation between minority carriers (holes) and main carriers (electrons) in Ag2Se. This carrier separation weakens carrier scattering of the Ag2Se‐based film and enhances the carrier mobility to a record‐high value of 1551.99 cm2 V−1 s−1. The 6 mol% PEI/Ag2Se composite film shows an improved S2σ of 22.39 µW m−1 K−2 at 300 K.