A general strategy to bismuth chalcogenide films by chemical vapor transport

Abstract

Developing a low-cost, simple manufacturing process for highly efficient thermoelectric films is an intriguing topic for both chemists and materialists. In this work, a new strategy was introduced to synthesize bismuth chalcogenide films by chemical vapor transport on presynthesized Bi films, including Bi₂Se₃, Bi₂Te₃ and Bi₂Te_2.7Se_0.3. Through delicate control of the chalcogen vapor pressure, highly qualified and (00l) oriented bismuth chalcogenide films, constructed by oriented nanoplates, were obtained. The (00l) orientation of the films will facilitate the transport of the carrier for bismuth chalcogenides. Thermoelectric properties of these films were also characterized. At room temperature, the power factors reach 3 μW cm⁻¹ K⁻¹, 18.7 μW cm⁻¹ K⁻¹, 24.6 μW cm⁻¹ K⁻¹ for Bi₂Se₃, Bi₂Te₃, Bi₂Te_2.7Se_0.3 films, respectively. Besides, the average power factor of 31.2 μW cm⁻¹ K⁻¹ in the temperature range of 300–500 K for Bi₂Te_2.7Se_0.3 films indicates the present chemical vapor transport process is a promising technique for thermoelectric films.