Composition-dependent optical limiting behavior of all-inorganic halide perovskite quantum dots

Nonlinear optical nanostructured materials are gaining interest as optical limiters for various applications. Here, all-inorganic halide perovskite quantum dots (PQDs, SiO2@CsPbX3 (X = Cl, Br, I) QDs) with tunable composition were prepared via ligand assisted reprecipitation, using 3-aminopropyltriethoxysilane as a ligand. The formation of the SiO2@CsPbX3 QDs was confirmed by transmission electron microscopy, X-ray diffraction, infrared spectroscopy, ultraviolet-visible absorption spectroscopy and photoluminescence spectroscopy. The compositiondependent optical limiting (OL) behavior of the SiO2@CsPbX3 QDs was observed using nanosecond and picosecond laser pulses at a wavelength of 532 nm. The SiO2@CsPbBr3 QDs exhibit favorable OL properties. Their OL threshold for the nanosecond laser pulse is 1.68 J/cm(2), which is comparable to that of carbon nanotube suspension (a benchmark optical limiter). The presence of chloride or iodide in the SiO2@CsPbX3 QDs leads to weaker OL performance. The OL behavior of the SiO2@CsPbBr3 QDs is attributed to the narrow band gap, large average size, abundant charge carriers under laser excitation and high stability. The OL mechanism was investigated using the open-aperture and closed-aperture techniques. The OL behavior of the SiO2@CsPbX3 QDs is largely attributed to the combined mechanisms of nonlinear absorption and nonlinear refraction. These results reveal the physical processes of the composition-dependent OL properties of the CsPbX3 QDs. These findings provide a means to tailor the OL response of PQDs by controlling the halide ion ratio.