Quantum dots are a class of nanomaterials composed of II-VI or III-V group elements. Quantum dots have quantum size effect, and their optical properties vary with the change of particle size. The luminescence efficiency of quantum dots is also greatly improved compared with that of bulk materials. Among the numerous quantum dots, Cd-based quantum dots have been studied most deeply. However, the use of heavy metals has brought great problems to the commercial production. Among all alternative materials for Cd-based quantum dots, InP quantum dots are considered as the most promising alternative materials. The reasons are that InP quantum dots have a band gap that is similar to Cd-based quantum dots and the whole visible range can be covered with the properties of band gap tunability. However, the surface defects of InP quantum dots will seriously affect the optical properties. In order to solve this problem, semiconductor shells with large gap width are generally used to enhance the luminescence of InP quantum dots. ZnS is a commonly used coating material for InP quantum dots. As a kind of green quantum dots, InP/ZnS quantum dots have a broad application prospect.
Figure 1. An example of InP/ZnS quantum dot.
Figure 2. An example of InP/ZnS quantum dots used in cell imaging.
According to the solubility, InP/ZnS quantum dots can be divided into water-soluble InP/ZnS quantum dots and non-water-soluble InP/ZnS quantum dots.