Liquid Exfoliation of Two-Dimensional PbI₂ Nanosheets for Ultrafast Photonics

Two-dimensional (2D) materials are showing promise in next-generation optoelectronic devices. To this end, large-scale production of defect-free 2D nanosheets is vital. Herein, we demonstrate scalable exfoliation and preparation of high-quality 2D PbI₂ nanosheets in cyclopentanone. The resulting dispersions can retain good stability over 30 days and can also sustain freezing treatment. The exfoliation kinetics was observed to fit an apparent pseudo-first-order process. Furthermore, the PbI₂ nanosheets exhibit excellent saturable absorption properties both at femtosecond and nanosecond pulse excitations in the visible region, thus showing potential application in the field of ultrafast saturable absorbers.