טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentMarina Sirota
SubjectSynthesis and Optical Studies of Nanoscaled Semiconductors
DepartmentDepartment of Chemistry
Supervisor Full Professor Lifshitz Efrat


Abstract

In recent years, there has been an increase of interest in the scientific and a technological aspect of semiconductor nanocrystals (NCs). These materials exhibit unique chemical and physical properties, associated with two important characteristics:  (1) the quantum size effect (QSE) and (2) the existence of a relatively large fraction of atoms at the surface.

The extensive study of individual NCs stimulated investigations in the engineering and synthesis of ordered or disordered arrays of NCs, which show new collective effects resulting from inter-NC or matrix-NC interactions in addition to the properties of individual NCs.

Based on the above, the present study concentrated on the design, synthesis and spectroscopic characterization of both the individual NCs and the hybrid materials, consisting of ordered NCs arrays incorporated in organic matrices

The properties of the individual NCs were investigated with the lead sulfide (PbS) NCs, embedded in solid and transparent polymer media. The synthetic methodology was developed for the preparation of PbS NCs of 2-15 nm in diameter in the polymer matrix.  The influence of quantum size effect and surface quality on the static and dynamic optical properties of the PbS crystals was examined.

We have studied possible inter - NCs and matrix - NCs interaction in the organized hybrid organic-inorganic structures, which consist of PbS, CdS or Cd1-XMnXS NCs planes, divided by aliphatic or fully conjugated organic chains, and ordered in the form of 3-dimensional crystals.  The molecular-wire/NCs hybrid structures show typical characteristics of the individual NCs and additional collective properties not encountered by the individual NCs.