Scalable and sustainable manufacturing of twin boundary-enhanced flexible Bi0.4Sb1.6Te3 films with high thermoelectric performance

Abstract

Flexible thermoelectrics (TEs) have been used in self-powered electronics and heat harvesters due to their matchable heat flux values across curved/non-flat interfaces, aiming to achieve a balance between thermoelectricity, flexibility, and scalability. In this work, we constructed Bi_0.4Sb_1.6Te₃ thin films with a high density of annealing twin boundaries to simultaneously modulate the carrier concentration, Seebeck coefficient, mobility, and local strain propagation. Specifically, the thin films achieved an ultrahigh power factor reaching 45 μW cm⁻¹ K⁻² and demonstrated modest electrical conductivity variations (<10%) after 1,000 bending cycles at room temperature. Furthermore, we presented a large-area, cost-effective thin film of up to 100 cm² and a flexible generator with an impressive maximum power density of 69 W m⁻² at a temperature difference of 56.8 K. This flexible TE could not only serve as a framework for comprehending the structure-property correlation in inorganic TE thin films but also provide feasibility for wearable electronics and sustainable heat harvesting.