PANI coupled hierarchical Bi2S3 nanoflowers based hybrid nanocomposite for enhanced thermoelectric performance

Abstract Bismuth sulfide (Bi 2 S 3 ) is a promising material for thermoelectric applications owing to its non-toxicity and high abundance of bismuth (Bi) and sulfur (S) elements on earth. However, its low electrical conductivity drastically reduces the value of the figure of merit ( ZT ). In this work, we have synthesized three-dimensional (3D) hierarchical Bi 2 S 3 nanoflowers (NFs) by the hydrothermal route and further incorporated them with conducting polymer polyaniline (PANI) by simple chemisorption method. We have investigated the thermoelectric properties of the as-prepared Bi 2 S 3 NFs and PANI/Bi 2 S 3 nanocomposite samples and it is demonstrated that the incorporation of the PANI matrix with the 3D hierarchical Bi 2 S 3 NFs provides a conducting substrate for the easy transport of the electrons and reduces the barrier height at the interface, resulting in ∼62% increment in the electrical conductivity as compared to Bi 2 S 3 NFs. Moreover, a decrement in the thermal conductivity of the PANI/Bi 2 S 3 nanocomposite is observed as compared to pristine Bi 2 S 3 NFs due to the increased phonon scattering at the interfaces facilitated by the hierarchical morphology of the NFs. Furthermore, an increment in the electrical conductivity and simultaneous decrement in the thermal conductivity results in an overall ∼20% increment in the figure of merit ( ZT ) for PANI/Bi 2 S 3 nanocomposite as compared to pristine Bi 2 S 3 NFs. The work highlights an effective strategy of coupling 3D hierarchical metal chalcogenide with conducting polymer for optimizing their thermoelectric properties.