MXene-Enabled Flash Sintering Toward Scalable Flexible Thermoelectric Development

Abstract

Flexible thermoelectric generators (f-TEGs) are a promising technology for harvesting low-grade waste heat to provide supplemental electrical power for flexible electronics. However, the large-scale market adoption of f-TEGs remains limited by the lack of manufacturing approaches that can simultaneously enable low thermal budget processing, mechanical flexibility, and high thermoelectric performance (ZT). Conventional sintering approaches utilize prolonged bulk-thermal exposures, thereby limiting design freedom and form factor flexibility. Moreover, the interdependence of electrical conductivity, Seebeck coefficient, and thermal conductivity in thermoelectric materials limits integration of conductive pathways that aid in selective energy delivery. Here, we report a scalable, energy-efficient fabrication strategy that combines flash sintering with MXene (Ti3C2) incorporation to produce high-density, thick (>200 µm) p-type Bi0.5Sb1.5Te3 (BST) thermoelectric films. Homogeneous MXene incorporation functions as a conductive nanoadditive, enabling efficient pulsed-light xenon energy delivery and uniform densification across thick films within milliseconds under ambient conditions. Subsequent topical MXene deposition introduces high-aspect-ratio BST/MXene heterointerfaces, enabling energy-barrier scattering that decouples electrical conductivity and Seebeck coefficient. The optimized BST−MXene flash-sintered films exhibit a power factor of 2100 µW/mK2 and a room-temperature ZT of 0.52, a ∼126% improvement over pristine BST films. Leveraging the flash-sintering MXene additive manufacturing process, a five-leg flexible thermoelectric generator is fabricated, delivering a maximum power output of 171.7 µW and a power density of 2.45 mW/cm2 at a temperature difference of 30 K with stability under bending tests. MXene-assisted flash sintering enables rapid, scalable fabrication of high-performance flexible thermoelectric devices.