Enhancing Thermoelectric Performance and Flexibility of Sb ₂ Te ₃ Thin Films through MAPbI ₃ ‐Induced Crystallographic Orientation Modulations and Interfacial Doping

Abstract Wearable thermoelectric (TE) devices have garnered significant attention, but achieving both high TE performance and flexibility in Sb 2 Te 3 ‐based systems remains a challenge. In this study, methylammonium lead iodide (MAPbI 3 ) is incorporated to simultaneously enhance the TE performance and mechanical flexibility of Sb 2 Te 3 thin films. The integration of MAPbI 3 introduces micro strain, modulating the crystal orientation by suppressing the (015) plane and enhancing the (00 l ) plane, leading to improved carrier mobility and electrical conductivity. Additionally, MAPbI 3 ‐induced interfacial doping reduces carrier concentration and increases the Seebeck coefficient. The introduced lattice defects, such as large‐angle grain boundaries, strengthen phonon scattering, significantly reducing thermal conductivity and yielding a high zT of 0.47 at 250 °C. The films demonstrate exceptional flexibility, as evidenced by a decrease in the resistance change ratio ( ΔR / R 0 ) from 54.6% to 8.7% upon MAPbI 3 incorporation, attributed to its lower Young's modulus. The fabricated device achieves a maximum output power of 33.5 nW under a temperature gradient of 10 K, consistent with finite element simulations, highlighting its promising potential for wearable electronics.