The effect of interlayer coupling on thermoelectricity in atomically thin CaGe₂: a first-principles study

We investigate the effect of interlayer coupling on thermoelectric properties of atomically thin CaGe 2 using first-principles calculations. By systematically varying the layer number from monolayer to trilayer, we demonstrate how interlayer coupling changes the electronic structure. This causes a transition from semiconducting to semimetallic behavior, consequently reducing thermoelectric performance. Specifically, the monolayer CaGe 2 achieves a power factor of 1.80 mWm -1 K -2 , significantly higher than multilayer structures, with an electron doping concentration of 8.53×10 19 cm -3 . These results show that interlayer coupling systematically reduces thermoelectric efficiency through band gap reduction. Our findings highlight the potential of monolayer CaGe 2 as a promising candidate for thin-film thermoelectric materials. Further experimental studies are needed to realize its practical applications.