Speakers
Descrizione
Organometal halide perovskites (OHPs) with general formula ABX₃ (A = organic cation, B = metal cation, X = halide) have emerged as promising candidates for thermoelectric (TE) applications owing to their hybrid “electron-crystal/phonon-glass” behavior. In these materials, the inorganic framework enables efficient charge transport, while the organic sublattice suppresses lattice thermal conductivity through enhanced phonon scattering, offering a pathway toward high thermoelectric performance (ZT = S²σT/κ).
Among OHPs, Sn-based compounds are particularly attractive as lead-free alternatives. Materials such as MASnI₃ and FASnI₃ exhibit relatively high intrinsic electrical conductivity (~1 S cm⁻¹), primarily arising from low formation energies of Sn vacancies and halogen-related defects, which induce significant p-type self-doping. However, the instability of Sn²⁺ under ambient conditions, leading to oxidation to Sn⁴⁺, strongly affects carrier concentration and transport properties, posing a key challenge for TE optimization.
In this work, we investigate the impact of air exposure on the structural, chemical, and electronic properties of Sn-based two-dimensional OHPs. We focus on elucidating the interplay between Sn oxidation, defect-mediated self-doping, and charge carrier density, and its consequences on TE-relevant transport parameters. By correlating compositional and structural evolution with electrical response, we identify stability thresholds and quantify changes in conductivity associated with environmental degradation.
These insights provide guidelines for controlling carrier concentration via intrinsic defect engineering and extrinsic doping strategies, with the goal of optimizing the power factor while maintaining low thermal conductivity. Our findings highlight both the opportunities and limitations of Sn-based 2D OHPs for thermoelectric applications and offer design principles for improving their performance and stability.
| Giovane Ricercatore (under 40) | Yes |
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