Charting the Lattice Thermal Conductivities of I-III-VI2 Chalcopyrite Semiconductors

Chalcopyrite-structured semiconductors have promising potential as low-cost thermoelectric materials, but their thermoelectric figures of merit must be increased for practical applications. Understanding their thermal properties is important for engineering their thermal conductivities and achieving better thermoelectric behavior. We present here a theoretical investigation of the lattice thermal conductivities of 20 chalcopyrite semiconductors with an ABX(2) composition (I-III-VI2) (A = Cu or Ag; B = Al, Ga, In, or TI; X = S, Se, or Te). To afford accurate predictions across this large family of compounds, we solve the Boltzmann transport equation with force constants derived from density functional theory calculations and machine learning-based regression algorithms, reducing by between 1 and 2 orders of magnitude the computational cost with respect to conventional approaches of the same accuracy. The results are in good agreement with available experimental data and allow us to rationalize the role of chemical composition, temperature, and nanostructuring in the thermal conductivities across this important family of semiconductors.

Automated summary

Chalcopyrite-structured semiconductors have potential as low-cost thermoelectric materials, but their thermoelectric figures of merit need improvement. In this study, the lattice thermal conductivities of 20 chalcopyrite semiconductors with an ABX(2) composition were theoretically investigated. The results, obtained using density functional theory calculations and machine learning-based regression algorithms, are in good agreement with experimental data and provide insights into the thermal conductivities of this important semiconductor family.