Thermal and Transport Properties of Novel Metal Oxychalcogenides for Energy Recovery

It is estimated that up to half of global energy input is lost to thermal processes.[1] Harvesting this waste heat and converting it into consumable, electrical energy is a viable route towards cleaner energy, and is made possible through the use of thermoelectric materials and the Seebeck effect. Historically, thermoelectrics contain heavy, toxic metals such as Pb, and are unsuitable for use in everyday society. The discovery of non-toxic, earth-abundant thermoelectrics is therefore highly desirable, enabling widespread improvements in energy efficiency and potential climate change mitigation.

Recently, the layered, mixed anion system Y₂Ti₂O₅S₂ was investigated as a potential n-type thermoelectric.[2] Here, we extend this investigation to the Ln₂M₂O₅Ch₂ family (Ln = Sc, Y, La, M = Ti, Zr, Hf and Ch = S, Se, Te), where we examine the effects of simultaneous cation and anion substitution on the electronic and phononic properties. We use AMSET[3], a python package that allows the calculation of scattering rates from first principles, to simulate charge carrier mobility, lifetimes and thermal transport properties. From this, we identify promising candidates for the calculation of lattice thermal conductivity and figure of merit (ZT).

 

[1] Firth, A. et al, Appl. Energy, 2019, 235, 1314

[2] Brlec, K. et al., J. Mat. Chem. A, 2022, 10, 16813

[3] Ganose, A. M. et al, Nat. Commun., 2021, 12, 2222