Ultrafast dynamics of photoconductivity in lead sulfide nanocrystals in terahertz region

Abstract The dynamics of carrier relaxation and charge transport of photoinduced carriers in Lead Sulfide nanocrystals with quantum confinement, synthesized by chemical bath deposition method, have been simultaneously determined using time-resolved terahertz spectroscopy with sub-picosecond time resolution. We use both Drude-Smith and Drude Lorenz model to successfully reproduce the photoconductivity spectra, which manifest that localized free-carriers not bounded excitons are responsible to the THz transport in PbS nanocrystals. The pump fluence dependence of carrier dynamics reveals the process of Auger recombination through the interaction between free carriers and excitons.