The Mechanisms of Size, Shape, and Facets Control in Colloidal SnTe Nanostructures for Advanced Optoelectronics

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Low-dimensional semiconductor nanomaterials such as tin telluride (SnTe) can adopt advantages based on the quantum confinement effect, suggesting great potential for heat-electricity conversion. As a IV-VI narrow bandgap semiconductor (0.18 eV, bulk), SnTe exhibits an intrinsically high charge carrier concentration, which results in a relatively low Seebeck coefficient, but optimization of the material through doping and alloying offers great promise for thermoelectric applications of this material. As the first predicted topological crystalline insulators, SnTe has been studied to explore the physics and applications of the surface states both theoretically and experimentally. In addition, SnTe exhibits exotic electronic properties such as superconductivity and ferromagnetism that make it a promising material for the use in high-performance thermoelectric materials, phase-change materials, infrared emission and detection materials, photovoltaic devices as well as ferroelectrics for a wide range of applications. In this project, the applicant intends to explore new approaches to control the size and shape of low-dimensional SnTe nanomaterials to improve the optical anisotropy, tunable electronic effects, unique optoelectronic behavior, and enhance sensing capabilities of SnTe nanomaterials. Controlling the particle size, shape and facets is still a challenge for the colloidal synthesis of SnTe nanomaterials. In addition, control of kinetic factors and the introduction of chelating agents in the medium decide the formation of nano-systems with phase purity, narrow size distribution and shapes. More importantly, to the applicant’s knowledge, no clear and systematic trends linking SnTe to their optical or optoelectronic properties have been established. This research project will focus on the relationship between the morphology and optoelectronic properties of SnTe nanocrystals. In terms of synthesis, the physical (e.g., reaction temperature, heating time, etc.) and chemical (e.g., type of ligand, nature of the solvent, etc.) parameters that affect the morphology of SnTe nanoparticles will be studied in detail. The proposed project also focuses on the factors that ultimately affect the shape of nanoparticles (e.g., electronic structure, facet formation, etc.) and the electric transport properties of the colloidal SnTe with different nanostructures to gain a deep understanding of the connection between the different morphologies and their optic or optoelectronic properties. From the fundamental research point of view, the project will help to understand the basic connection between SnTe nanostructures with their optoelectronic properties. The results of this study will benefit the controllable synthesis of SnTe with defined structures as well as the exploration of novel optic or optoelectronic devices and topological crystalline insulators.