Nonlinear optical absorption and ultrafast carrier dynamics in layered tin diselenide quantum dots

Abstract

Quantum dots (QDs) derived from typical two-dimensional materials present attractive unique chemical and physical properties because of the quantum-confinement effect. Herein, high-quality layered tin diselenide (SnSe2) QDs with controllable size and thickness were prepared from layered bulk SnSe2 crystals using a simple, effective, and economical mechanical and liquid exfoliation technique. The resulting SnSe2 QDs were subsequently incorporated into chemically stable transparent silica-gel glasses using a sol–gel method. The nonlinear optical (NLO) absorption of the SnSe2 QDs was systematically explored using a combination of open-aperture Z-scan and pump–probe technologies. The derived NLO parameters and ultrafast carrier dynamics of the QDs were comparable to those of reported low-dimensional materials. Interestingly, the layered SnSe2 QDs exhibited thickness/layer-dependent NLO properties and pulse duration-dependent saturable absorption and reverse saturable absorption in both dimethylformamide suspensions and solid silica-gel glasses. Such unique NLO characteristics make layered SnSe2 QDs a promising candidate for technological innovations in areas including optoelectronics and nonlinear optics.