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  Partner: UNT Libraries
 Department: Department of Materials Science and Engineering
 Decade: 2010-2019
 Degree Discipline: Material Science and Engineering
First Principle Calculations of the Structure and Electronic Properties of Pentacene Based Organic and ZnO Based Inorganic Semiconducting Materials

First Principle Calculations of the Structure and Electronic Properties of Pentacene Based Organic and ZnO Based Inorganic Semiconducting Materials

Date: May 2012
Creator: Li, Yun
Description: In this thesis, I utilize first principles density functional theory (DFT) based calculations to investigate the structure and electronic properties including charge transfer behaviors and work function of two types of materials: pentacene based organic semiconductors and ZnO transparent conducting oxides, with an aim to search for high mobility n-type organic semiconductors and fine tuning work functions of ZnO through surface modifications. Based on DFT calculations of numerous structure combinations, I proposed a pentacene and perfluoro-pentacene alternating hybrid structures as a new type of n-type semiconductor. Based on the DFT calculations and Marcus charge transfer theory analysis, the new structure has high charge mobility and can be a promising new n-type organic semiconductor material. DFT calculations have been used to systematically investigate the effect of surface organic absorbate and surface defects on the work function of ZnO. It was found that increasing surface coverage of organic groups and decreasing surface defects lead to decrease of work functions, in excellent agreement with experimental results. First principles based calculations thus can greatly contribute to the investigating and designing of new electronic materials.
Contributing Partner: UNT Libraries
Interspecimen Study of Bone to Relate Macromechanical, Nanomechanical and Compositional Changes Across the Femoral Cortex of Bone

Interspecimen Study of Bone to Relate Macromechanical, Nanomechanical and Compositional Changes Across the Femoral Cortex of Bone

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Date: May 2013
Creator: Nar, Mangesh
Description: Mechanics of bone is widely studied and researched, mainly for the study of fracture. This has been done mostly on a macro scale. In this work hierarchical nature of bone has been explored to investigate bone mechanics in more detail. Flexural test were done to classify the bones according to their strength and deflection. Raman spectroscopy analysis was done to map the mineralization, collagen crosslinking changes across the thickness of the bone. Nanoindentation was done to map indentation hardness and indentation modulus across femoral cortex of the bone. The results indicate that the composition of the bone changes across the thickness of the femoral cortex. The hypothesis is confirmed as increase in mineralization, carbonate to phosphate ratio and collagen crosslinking shows the effect as increased indentation hardness and modulus and decreased deflection.
Contributing Partner: UNT Libraries