Spectroscopic properties of yellow and red InP/ZnSe/ZnS quantum dots

Abstract

As promising fluorescent semiconductor materials, InP quantum dots (QDs) have been widely used in various applications. However, an in-depth understanding of the fundamental optical properties of InP QDs is the premise of expanding their related applications. In this work, the spectroscopic properties of yellow and red InP/ZnSe/ZnS QDs have been compared. It is found that the yellow QDs exhibit a more serious Auger effect than the red QDs. We further elucidate that the red QDs possess a longer hot carrier cooling time as a result of weaker carrier–phonon coupling strength. In addition, the InP/ZnSe/ZnS QDs present efficient two- to four-photon absorption cross-sections from 800 to 2120 nm. Interestingly, aqueous red QDs are prepared and relevant two-photon fluorescence imaging is demonstrated. These findings constitute a comprehensive understanding of the fundamental optical properties of InP/ZnSe/ZnS QDs.