טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentKolan Dikla
SubjectDevelopment snd Characterization of Anisotropic
Shaped Nanocrystals
DepartmentDepartment of Chemistry
Supervisor Professor Lifshitz Efrat
Full Thesis textFull thesis text - English Version


Abstract

Colloidal semiconductor nanostructures are inorganic particles that are stabilized by a layer of surfactants attached to their surface. These structures provide great scientific interest and applicable potential due to the quantum size effect (QSE). The main consequence of the QSE is the size dependence of the optical properties. Nanocrystals (NCs) which belong to the IV-VI group (specifically, lead sulfide and lead selenide) open a window to many future applications. This, thanks to their unique electronic structure and their optical activity in the near infrared (NIR). These materials exhibit a large Bohr radius, making them well suited for the study of the strong-confinement limit. Furthermore, their close lattice parameters allow the growth of high quality heterostructures.

The development of anisotropic inorganic nanocrystals has become one of the most active trends in modern materials chemistry. Anisotropic nanostructures provide an interesting opportunity for investigating how shape and dimensionality play major role in controlling the optical properties. In particular, semiconductor nanorods (NRs) hold great potential for technological advantages over spherical nanocrystals in applications such as polarized light emitters and photovoltaics.

This study focuses on the development and characterization of anisotropic lead chalcogenides. The studied materials were synthesized by means of colloidal chemistry. Their characterization was carried out through several techniques such as transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive analysis of X-ray (EDX), and optical measurements. The structures presented in this study reveal high crystallinity and tunability of the band-edge offset with variation of the size and composition.