Influence of the Disordered Behaviour of Cu atoms on the Thermoelectric Performance of Cu₄TiSe₄

Thermoelectric materials can achieve the interconversion of thermal and electrical energy, which means that wasted thermal energy (about 50% of global energy) can be recycled through the Seebeck effect.¹ The performance of thermoelectric materials is evaluated by the thermoelectric figure of merit (ZT). Over many years, a number of materials with excellent thermoelectric performance have been predicted by calculations based on density functional theory (DFT). Although the thermoelectric performance of a series of ordered materials has been explored, many materials exhibit disorder in the positions of some of the atoms, which makes it difficult to conduct a study of these materials based on DFT calculations alone. However, recent studies have shown that a combination of DFT, alloy cluster expansion (CE) and Monte Carlo (MC) simulations can effectively address this challenge.^2,3

Cu₄TiSe₄ is considered a promising candidate for thermoelectric materials due to its ultra-low thermal conductivity at room temperature, and its room-temperature structure exhibits positional disorder at two Cu sites.⁴ Although some studies^5,6 have predicted high ZT values for ordered Cu₄TiSe₄ by combining the Boltzmann transport equation and first-principles calculations, the effect of the experimentally observed disordered behaviour of Cu atoms on the thermoelectric performance of Cu₄TiSe₄ has never been fully discussed. Therefore, in this work, we combine DFT calculations, alloy CE and MC simulations to systematically investigate the effect of Cu atomic disorder on the electronic and thermal transport properties of the material, aiming to reveal the underlying mechanisms by which disorder affects ZT.

References
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