Investigation of electronic structure, electrical and thermal properties of PbS quantum dots for thermoelectric applications

• Published in: Materials science in semiconductor processing 2022-09, Vol.148, p.106789, Article 106789
• Main Authors: Suganya, G, Arivanandhan, M, Kalpana, G
• Format: Article
• Language: English
• Subjects: Density of states; PbS NPs; PbS QDs; Quantum espresso; Thermoelectric
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2022.106789

PbS nanoparticles (NPs) and PbS quantum dots (QDs) were prepared by co-precipitation method and simple chemical bath method, respectively and their thermoelectric properties were comparatively investigated. The structural, morphological, optical, functional groups and pore size of PbS NPs and PbS QDs were analysed by XRD, UV-DRS, FTIR and BET analysis. TEM images revealed spherical morphology of PbS QDs with size ranging from 5 to 10 nm. The band gap value of PbS QDs calculated from UV-DRS is 1.20 eV which is relatively higher compared to PbS NPs (0.73 eV). This may due to the effect of quantum confinement. From the BET analysis the specific surface area was obtained as 66.031 m2 g−1. Quantum Espresso package based on Plane Wave-based Pseudopotential (PWSCF) approach was used to calculate the energy spectrum of PbS QDs of various sizes. The calculated energy gap value between the HOMO and LUMO levels is found to vary with PbS cluster size. Thermoelectric measurements showed that pelletized sample of PbS QDs exhibit a large Seebeck coefficient, high power factor and low thermal conductivity resulted in large figure of merit. The figure of merit of pelletized sample of PbS QDs at 403 K is 0.34 which is relatively higher than that of pelletized PbS NPs (0.24) at the same temperature, making it highly suitable for thermoelectric applications. [Display omitted] •PbS NPs and PbS QDs were synthesized by co-precipitation and simple chemical bath methods respectively.•The electronic structure of PbS QDs were simulated by DFT first principal calculation.•PbS QDs show high thermoelectric figure of merit of 0.34 compared to the PbS NPs (0.24).