Blue luminescent silicon nanocrystals prepared by ns pulsed laser ablation in water

Here the authors report on a simple and cost-effective procedure to prepare blue luminescent colloidal silicon nanocrystals (Si-ncs) in de-ionized water at room temperature and atmospheric pressure by nanosecond pulsed laser ablation. At low laser fluences well-separated and spherical Si-ncs aggregates are formed. The fluence increase leads to fragmentation of spherical aggregates and the generation of finer Si-ncs with quantum confinement size effect. After aging in de-ionized water, such irregular Si-ncs fragments get stabilized into quite regular spheres and ovals. During the aging process the increase of blue room temperature photoluminescence centered around 2.9eV is recorded.