Synthesis, Optical Properties, and Ultrafast Electronic Relaxation Dynamics of Colloidal Bi_2S_3 Nanoparticles

摘要

We report first direct measurements of ultrafast electronic relaxation dynamics in Bi_2O_3 colloidal nanoparticles using femtosecond transient absorption spectroscopy and compare with PbI_2 and BiI_3, two similar layered semiconductors. The Bi_2S_3 nanoparticles are prepared using colloidal chemistry methods in aqueous environment using different stabilizing agents and in inverse micelles. The particle size and shape are determined using low and high resolution transmission electron microscopy. Using a particle-in-a-rectangular box model, the calculations of the peak positions, with support of TEM images, indicate that the particles have bilayer disk-like structures. Comparison to PbI_2 and BiI_3 showed both interesting similarities and differences. The electronic relaxation dynamics studied as a function of particle size and surfactant suggest that the surface play a dominant role in the electronic relaxation processes in these layered semiconductor systems.