Enhanced Thermoelectric Performance in Flexible Sulfur-Alloyed Ag<sub>2</sub>Se Thin Films
Yi Luo, Shuaihang Hou, Yijie Liu, Xiaoyu Sun, Zunqian Tang, Fangyuan Yu, Jun Mao, Qian Zhang, Feng Cao
Abstract
Flexible thermoelectric generators can directly convert thermal energy harvested from the human body into electricity. The Ag 2 Se flexible film, a promising material for wearable thermoelectric generators, normally demonstrates an inferior electrical transport property due to its weakened in-plane mobility. In this study, the in-plane electrical transport properties of flexible Ag 2 Se films were optimized by alloying with additional sulfur. This optimization is achieved by leveraging the differences in elemental electronegativity and the preferred orientation of the Ag 2 Se films. The sulfur-alloyed Ag 2 Se thin film, with a nominal ratio of 3 atom %, can reach a maximum mobility of 1150 cm –2 V –1 s –1 at 300 K. So, the optimized room-temperature power factor increases to 1935 μW m –1 K –2 . Furthermore, the Ag 2 Se film alloyed with 3 atom % sulfur exhibits excellent flexibility even after 1000 bending cycles with a radius of 5 mm, characterized by a relative resistance increment of less than 3%. In addition, the corresponding π-type flexible thermoelectric generator possesses a maximum power density of 51 W m –2 at a temperature difference of 50 K.