High carrier mobility of few-layer PbX (X = S, Se, Te)

Abstract

Two-dimensional materials with a higher carrier mobility are promising materials for applications in nanoelectronics and photocatalysis. In this paper, we have explored the stabilities, structures, electronic properties, carrier mobility and optical properties of few-layer PbX (X = S, Se, Te) by first-principles calculations. Theoretical results show that the band gaps of PbX could be modulated by the thickness, changing from 1.65 eV (1.26 eV, 1.26 eV) for a monolayer to 0.98 eV (0.76 eV, 0.97 eV) for a tri-layer for PbS (PbSe, PbTe). Most importantly, the bi-layer PbS has an extremely high electron carrier mobility of 252 000 cm² V⁻¹ s⁻¹ and the hole carrier mobility of mono- or tri-layer PbTe could possess a value of 16 000 cm² V⁻¹ s⁻¹; thus, few-layer PbXs can have possible wide applications in novel electronic devices. The strong adsorptions of light of the PbX species also shows their potential implications in solar cells.