Enhanced thermoelectric performance of sustainable earth-abundant two-dimensional Galena (PbS)

Earth’s abundant lead sulfide (PbS) is gaining increasing attention for its thermoelectric properties, particularly in converting heat into electricity at room to mid-temperatures. While several studies have reported enhancements in the thermoelectric figure of merit, commonly referred to as the figure of merit, ZT, for bulk PbS through alloying, its high lattice thermal conductivity significantly limits overall performance. In this study, we present the synthesis and thermoelectric characterization of liquid phase exfoliated 2D PbS, highlighting its improved figure of merit across a range of temperatures. Our measurements indicate a Seebeck coefficient of − 275 µV/K and a high electrical conductivity of 2.7 KS/m, yielding an enhanced figure of merit, ZT, of approximately 0.8 at 550 K. Furthermore, density functional theory (DFT) calculations validate the thermoelectric mechanisms in both bulk and 2D PbS, revealing weak electron–phonon coupling in the 2D form, which contributes to its superior thermoelectric performance. Therefore, 2D PbS holds promise for applications in portable and wearable electronics.