Synthesis of InP Quantum Dots and Their Application

Abstract

For more than two decades, research interest has been focused on groups II–VI of quantum dots (QDs) because of their potential applications in lasers, light-emitting diodes, and biological imaging. Given the highly intrinsic toxicity of cadmium, the biological applications of Cd-QDs have been limited. The European Union prohibits the use of Cd-QDs in electronic devices by 2017 (Anc et al. in ECS J Solid State Sci and Technol 2:R3071, 2013 [1]. This problem is addressed by developing Cd-free QDs. Groups III–V QDs exhibit narrow full width at half maximum compared with other Cd-free QDs, such as CuInS₂, and are suitable for backlight units. With increasing number of related publications, the main attraction to these semiconductors focuses on the robustness of the covalent bond in groups III–V semiconductor materials rather than the ionic bond in groups II–VI semiconductors. Moreover, the covalent bond can enhance the stability of Cd-free QDs. Indium phosphide (InP) core easily facilitates non-radiative decay because of the surface environment. Thus, other semiconductors with larger bandgap should be preferred over InP to prevent solvent quenching. The recombination of hole and electrons decreases with increasing shell thickness, and the photoluminescence intensity consequently increases. Many synthesis strategies are available for InP QDs, including one-pot, hydrothermal, and continuous heating-up methods. In this chapter, we introduce these three techniques, and an example is given for each method to achieve further understanding.