Trace doping leads to texture engineering and boosts thermoelectric performance of Bi0.5Sb1.5Te3-based flexible thin films

The p -type Bi 0.5 Sb 1.5 Te 3 -based flexible thermoelectric thin films demonstrate exceptional potential for on-chip thermal regulation of next-generation wearable electronics. However, the inferior thermoelectric performance deriving from low carrier mobility, is refraining their wide applications. Taking magnetron-sputtering-prepared Bi 0.5 Sb 1.5 Te 3 -based flexible thermoelectric thin films as examples, this study demonstrates that trace Cu doping can effectively boost the formation of (00 l )-preferred texture, resulting in substantially improved thermoelectric performance. Cu doping preferentially replaces Sb atoms, forming Cu Sb point defects, decreases the surface formation energy of (00 l ) planes, and boosts the formation of (00 l )-preferred texture. The strengthened (00 l )-preferred texture leads to the high carrier mobility of ~23.54 cm 2 V −1 s −1 and excellent electrical conductivity of ~755.05 S cm −1 due to weakened carrier scattering. Consequently, a high room-temperature power factor to ~13.76 μW cm −1 K −2 is achieved. This study demonstrates a trace composition design can effectively boost the formation of (00 l )-preferred texture in Bi 0.5 Sb 1.5 Te 3 -based flexible thermoelectric thin films, contributing to high thermoelectric performance, and extend their application potentials. • Minor Cu-doping can boost the formation of ( 00 l )-preferred texture. • Strengthened texture enhances carrier transport and electrical conductivity. • The thin film with a maximum power factor of ~13.76 μW cm −1 K −2 was achieved. • A device generates a power density of ~121.65 μW cm −2 at ΔT of ~30 K.