Orientation-engineered Bi0.5Sb1.5Te3 films with enhanced mobility for high-performance thermoelectric and photothermoelectric energy conversion

Bi2Te3-based thermoelectric films remain leading candidates for near-room-temperature power generation and cooling, yet further enhancement of their performance is required for practical applications. Here, highly oriented Bi0.5Sb1.5Te3 films were prepared by pulsed laser deposition, and carrier mobility was enhanced from 28.4 to 193.8 cm2 V−1 s−1 through orientation engineering. Consequently, a high room-temperature power factor of 56.7 μW cm−1 K−2 was achieved, positioning these films among the state-of-the-art (Bi,Sb)2Te3-based thin films. A corresponding Bi0.5Sb1.5Te3-based thermoelectric generator delivered a power density of 220.0 W m−2 at ΔT = 60 K, exceeding or comparable to those of previously reported thermoelectric film devices. In addition, a photothermoelectric device integrating antireflection and radiative cooling layers exhibited a peak output power of 75 nW under an irradiation intensity of 1.5 kW m−2. These results demonstrate the strong potential of orientation-engineered Bi0.5Sb1.5Te3 films for efficient thermoelectric and photothermoelectric energy conversion, highlighting their applicability in next-generation green energy technologies.