자료유형  

 학위논문

Control Number  

0016934569

International Standard Book Number  

9798380483049

Dewey Decimal Classification Number  

600

Main Entry-Personal Name  

Kashani, Somayeh.

Publication, Distribution, etc. (Imprint  

[S.l.] : North Carolina State University., 2023

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2023

Physical Description  

1 online resource(182 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 85-04, Section: B.

General Note  

Advisor: Ade, Harald.

Dissertation Note  

Thesis (Ph.D.)--North Carolina State University, 2023.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Summary, Etc.  

요약Advantages of organic solar cells include their low cost, solution processing, tunability, light weight, and flexibility. Despite their potential, their efficiency is lower than that of inorganic counterparts due to significant energy loss during the charge generation and transport process. The main contributions to the energy loss is essentially rooted in the high exciton binding energy and large reorganization energy exhibited by the materials.The focus of the first half of this thesis is on relating reorganization energies, exciton diffusion length and non-radiative recombination to the room temperature UV-vis absorption spectra of NF-SMA in dilute solutions (i.e., in the single molecule regime). Using multi-parameter Franck-Condon (MFC) analyses along with density-functional theory (DFT) quantum chemistry calculation, a correlation between molecular structure, reorganization energy, and conformational diversity in a group of NF-SMAs is established. The results of MFC/DFT analyses reveal that Y6 molecule exhibits the smallest intra-molecular reorganization energy among the materials studied. Linear ITIC-like molecular structures reveal larger reorganization energies and reduced conformational uniformity compared to Y6. Meanwhile structures such as IDTBR and IEICO, which have an extra π-conjugated moiety between the donor and acceptor moieties, have large excited-state reorganization energies and low degrees of conformational uniformity. The significance of these findings lies in the fact that MFC/DFT analyses of room temperature UV-vis absorption spectra are much easier to perform experimentally compared to other methods used to measure reorganization energies, making it a highly useful tool. Furthermore, the close agreement between the experimental results and density functional theory (DFT) calculations suggests that DFT can be utilized for designing molecules with low relaxation energies and single conformations in silico, with the goal of minimizing energetic disorder. In future research, the MFC/DFT technique can be applied to a wider range of materials, including polymers and new emerging SMAs, and/or can be extended to thin films to accurately estimate reorganization energy in a device structure setting.The latter part of this dissertation examines the exciton binding energy (Eb) in organic semiconductors. Following the traditional definition of exciton binding energy (Eb = Et − Eopt), exciton binding energy of different variants of the PBnDT-TAZ polymer was investigated the study investigated the exciton binding energy of various forms of the PBnDT-TAZ polymer. The primary focus was on the two commonly used techniques for measuring the transport gap, which include the combination of ultraviolet photoelectron spectroscopy and inverse photoelectron spectroscopy (UPS-IPES) and solid-state cyclic voltammetry (CV). A correlation between the molecular structure of the FTAZ variants and Eb was found in the range of 200 meV-1 eV using CV measurements. In contrast, the UPS-IPES technique resulted in a small apparent Eb, between 0 and 600 meV, that does not exhibit an obvious structural correlation. To validate these results, external quantum efficiency (EQE) and electro-absorption spectroscopy (EAS) measurements were also utilized. The observed discrepancy was explained based on the time and spatial dependency of Eb, as well as the limitations of each method to accurately estimate the transport gap and exciton binding energy. Consequently, the reliability of estimating Eb using both CV and UPS-IPES is limited, making the utility of each approach context-dependent. Furthermore, the relationship between molecular structure and Eb observed in the CV results may be influenced by solvent and electrolyte effects, suggesting that high dielectric environments could potentially decrease Eb. This topic could be explored in future research.

Subject Added Entry-Topical Term  

Mechanical properties.

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Polymers.

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Electrolytes.

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Electrodes.

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Oxidation.

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Semiconductors.

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Carbon.

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Solvents.

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Electric fields.

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Hydrogen.

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Sulfur.

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Selenium.

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Polymer films.

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Optical properties.

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Energy.

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Spectrum allocation.

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Molecular structure.

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Materials selection.

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Geometry.

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Interfaces.

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Nitrogen.

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Electrical engineering.

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Electromagnetics.

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Mechanics.

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Optics.

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Physics.

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Polymer chemistry.

Added Entry-Corporate Name  

North Carolina State University.

Host Item Entry  

Dissertations Abstracts International. 85-04B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

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Control Number  

joongbu:639852