Thermoelectric performance of Cu3InSnSe5 and MnSe pseudo-binary solid solution

Cu₃InSnSe₅ is a newly discovered copper-based diamond-like thermoelectric semiconductor, whose thermoelectric performance can be further enhanced by the MnSe alloying herein. We observed the formation of MnSe₂ precipitates that effectively scattered low-frequency phonons, which significantly reduced the lattice thermal conductivity at mid-to-low temperatures. While a high amount of MnSe alloying led to the formation of MnSe₂ precipitates which enhanced the phonons scattering, a smaller MnSe content improved the power factor in a certain as well. Ultimately, our research achieved a peak ZT of 1.00 and an average ZT of 0.50 over the 300–773 K temperature range by 10 mol.% MnSe alloyed Cu₃InSnSe₅ pseudo-binary solid solution, demonstrating the potential of MnSe alloying for optimizing the thermoelectric performance of copper-based diamond-like semiconductor materials.