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.