High thermoelectric performance of aluminum-doped cuprous selenide thin films with exceptional flexibility for wearable applications

Abstract

Flexible thin-film generators are a great promising energy source for wearable device applications. In this work, Al-doped Cu2Se thin film with highly (0l0) preferred orientation was achieved by magnetron co-sputtering deposition. It possessed a high ZT value of 0.76 at 275 °C, and further surface organic component coating treatment resulted in its exceptional flexibility. The Al dopant was proven to be successfully introduced into the lattice of Cu2Se samples, which can decrease carrier concentration and result in the enhancement of Seebeck coefficient. Meanwhile, a significant decline in lattice thermal conductivity was achieved after Al doping. The organic component coating can prevent the fracture of inorganic thin films after bending. The resistance difference (∆R/R0) after 1000 cycles of bending was lower than 10%, which is a great improvement compared with that in pristine thin film (over 15%). The thermoelectric device prepared by the Al-doped Cu2Se obtained a stable power density of ∼5.7 W m−2 at a temperature difference of 20 °C.