SEMINARIUM INSTYTUTOWE

Dnia: 13.05.2026 roku (środa)
o godzinie 13:00 w auli Instytutu Fizyki Molekularnej Polskiej Akademii Nauk w Poznaniu

referat pt.:

Copper-based materials for thermoelectric applications

wygłosi

dr Peter Murmu

Earth Sciences New Zealand (formerly GNS Science)

Thermoelectric materials directly convert heat into electricity for thermal energy harvesting and waste heat recovery. Key intrinsic properties such as electrical conductivity (σ), Seebeck coefficient (α), and thermal conductivity (κ) must be carefully optimized to achieve a delicate balance among these adversely interrelated parameters. Crystal defects play a crucial role in governing electronic and thermal transport in thermoelectric materials. Defect engineering enables atomic-scale modification of lattice structures to enhance power factors (α²σ) while reducing thermal conductivity [1]. Copper-based thermoelectric materials (TEMs) exhibit diverse defect-related transport phenomena, providing opportunities to design highly efficient TEMs. In particular, copper iodide (CuI) possesses attractive features such as a wide bandgap (E_g ~ 3.1 eV), intrinsic p-type conductivity, and low-temperature fabrication. However, acceptor states originating from copper vacancies (V_Cu) are pinned near the Fermi energy due to the formation of compensating defects [2], making further optimization challenging. Ion beam modification techniques have been shown to address this limitation by tailoring lattice defects and promoting beneficial defect complexes [3]. 

We investigated defects and their complexes in ion-beam-sputtered CuI thin films [4–6]. Low-energy (E < 100 keV) ion implantation was performed using various dopants, including metals (Sn, Sb), chalcogens (S, Se, Te), and noble gases (He, Ne, Ar, Kr, Xe), with fluences ranging from 1 × 10¹⁴ to 1 × 10¹⁷ ions/cm². Ion implantation causes the abundant production of Frenkel pairs, which were found to suppress compensating donors in CuI. Supported by density functional theory (DFT) and TRIM Monte Carlo simulation results show that ion implantation stabilizes acceptor states [3,4]. The increased power factor is due to a decoupling of the Seebeck coefficient and electrical conductivity identified through a changing scattering mechanism. The talk will provide a detailed explanation of ion-beam-induced defects and defect complexes, with a focus on optimizing the power factor to design more efficient Cu-based thermoelectric materials.

References:

[1]   Wu, C., et al., ACS nano, 18 (2024) 31660-31712.

[2]   Liu, A., et al., Adv. Sci., 8 (2021) 2100546.

[3]   Kennedy, J., et al., J. R. Soc. N. Z., 51 (2021) 574-591.

[4]   Murmu, P.P., et al., ACS Appl. Energy Mater., 3 (2020) 10037-10044.

[5]   Murmu, P.P., et al., Mater. Today Energy, 44 (2024) 101639.

[6]   Markwitz, M., et al., Appl. Phys. Lett. 125 (2024) 213901.