Thermoelectric Properties of Flexible Bi–Sb–Mn Films and Output Power of the Generator

Abstract

In this work, the Bi–Sb films with different Mn-doping contents were prepared on polyimide (PI) substrates by high vacuum magnetron sputtering. The carrier transport process, thermoelectric properties, flexibility of the deposited Bi–Sb–Mn films, and output power of the thermoelectric generator were studied. Results showed that the carrier concentration increased and carrier mobility and energy gap decreased with increasing doping Mn content in deposited Bi–Sb–Mn films. The electrical conductivity, Seebeck coefficient, and power factor all first increased and then decreased with increasing doping Mn content. The deposited Bi–Sb–Mn film with 1.0 at % Mn doping content possessed a maximum electrical conductivity of 5.30 × 10⁴ S m^–1, a Seebeck coefficient of −105.86 μV·K^–1, and a power factor of 624.22 μW m^–1 K^–2. The loss of electrical conductivity increased with increasing bending angles and bending times, and the loss greatly decreased with Mn doping in Bi–Sb films. The bending flexibility of Bi–Sb films can be further improved by doping more Mn. The maximum output power density (PD_max) of the thermoelectric generator for the deposited Bi₈₂–Sb₁₇–Mn film with 1.0 at % Mn doping content was 1.64 and 3.22 W·m^–2 at ΔT = 30 and 45 K, respectively. The standardized maximum power density (PD_max·L/ΔT²) of the thermoelectric generator for the Bi₈₂–Sb₁₇–Mn (1.0 at % Mn) film reached 72.89 μW·m^–1·K^–2, which was approximately 2.44 times higher than that of the undoped Bi₈₄–Sb₁₆ film.