Quantum confinement-induced enhanced nonlinearity and carrier lifetime modulation in two-dimensional tin sulfide

Two-dimensional tin sulfide (SnS), as a black phosphorus-analogue binary semiconductor, has received considerable attention in photonics and optoelectronics. Herein, the third-order nonlinearity susceptibility Im chi(3) is enhanced from -(6.88 +/- 0.10) x 10(-14) esu to -(1590 +/- 0.27) x 10(-14) esu by the size-related quantum confinement in layered SnS nanosheets. Due to the energy level alignment, a phonon-bottleneck effect is observed, which leads to a prolonged carrier lifetime. These results provide a platform for actively tuning the linear and nonlinear optics, and pave the way for designing SnS-based tunable and anisotropic optoelectronic devices.