Polypyrrole-bismuth selenide (PPY-Bi2Se3) composite-thermoelectric characterization and effect of nickel doping

Conducting polymer based thermoelectric composites have received an increasing attention due to their inexpensive process, low thermal conductivity, durability and flexibility in last few years. Compositing polymer with chalcogenides imparts enhancement of properties by suitable choice of dopant. The performance of Polypyrrole-bismuth selenide (PPYBS) and polypyrrole-nickel doped bismuth selenide (PPYBSN) composites synthesized solvothermally followed by chemical oxidative in situ polymerization technique for thermoelectric applications are compared. X-ray diffraction (XRD) pattern confirms the uniform growth of polypyrrole (PPY) matrix on Bi2Se3 nanoplates. Williamson-Hall (W-H) plots give crystallite size 26.3 and 22.9 nm for PPYBS and PPYBSN respectively. Comparative results for both the samples are further analysed employing density functional theory (DFT) to explore the underlying electronic structure and charge transfer processes in the nanocomposites which shows that after forming the composites with Bi2Se3 and nickel doped Bi2Se3density of state increases compared to pure PPY and hence conductivity increases from 1250 S/m to 1782 S/m and 2370 S/m respectively. Temperature variations of thermoelectric performance are measured in temperature range 303–373 K. Thermoelectric figure of merit (ZT) are 0.0108 and 0.0149 for PPYBS and PPYBSN respectively at room temperature.