First-principles study on layered thermoelectrics CaSi₂

The material CaSi 2 has been extensively studied in recent years, particularly due to its heavy group IV element layers in the Zintl phase, such as the deintercalation of Ca ions from CaSi 2 in acidic solutions. Tensile stress-induced transition from 6R-CaSi 2 to 3R-CaSi 2 during slow cooling significantly alters its structural and electronic properties, enhancing its potential for thermoelectric applications. We investigate the thermoelectric properties of CaSi 2 using density functional theory (DFT) calculations with the generalized gradient approximation (GGA) Perdew-Burke-Ernzerhof (PBE) method. Thermoelectric properties were calculated using semiclassical Boltzmann transport theory. Our results show significant Seebeck coefficient variations in monolayer CaSi 2 across different temperatures, highlighting its adaptability for thermoelectric applications. Structural modifications and thin-film fabrication enhance thermoelectric performance, making CaSi 2 a promising candidate for high-performance thermoelectric applications.