Solution-mixed PANI-coated Bi2Si2Te6 nanosheet-based composite film for flexible thermoelectric energy harvesting

This paper introduces a novel approach for flexible thermoelectric energy (TE) harvesting via the synthesis and characterization of polyaniline (PANI)-coated Bi2Si2Te6 nanosheet (NS) composite films. The study focuses on enhancing the TE performance of the Bi2Si2Te6 NSs by coating their surfaces with PANI via a solution-mixing method. Specifically, the process involves exfoliation of Bi2Si2Te6 into nanosheets, followed by coating with camphorsulfonic acid (CSA)-doped PANI. An investigation of the TE power factor of the PANI-coated Bi2Si2Te6 NS is then conducted by analyzing the influence of the PANI coating times, and the results are explained in terms of the charge-carrier transport. Thus, the PANI-coated Bi2Si2Te6 NS composite films obtained using two coating cycles are shown to exhibit a maximum power factor of (∼411 μW/m·K2 at 500 K). Further, the flexibility and bending stability of the composites are revealed by an evaluation of their mechanical properties. Moreover, the as-fabricated PANI-coated Bi2Si2Te6 NS composite films exhibit outstanding durability after 1000 bending cycles. The findings contribute to the advancement of flexible inorganic/organic hybrid TE materials and their practical applications.