| dc.description.abstract | This thesis includes two parts. The first part is about molecular design, synthesis and characterizations of model compounds. The studied model molecules can be categorized into three series. The first series of model compounds is composed of symmetric and unsymmetric three-branched structures, which uses triazolopyridine and benzothiazole as electron-withdrawing groups and a central nitrogen atom as the electron-donor. The second series of model compounds utilizes thiophene-triazolopyridine as the central core and end-capped with various electron-donating groups to
form linear type structures. The third series of model chromophores possess unsymmetric structures using functionalized fluorene, thiophene and triazolopyridine as the constructing units. Various experiments that measure linear and nonlinear optical properties were performed including linear absorption spectra, linear emission spectra, quantum yields, lifetime, multiphoton absorption spectra and power-dependence measurements. Three features based on the relationship between measured optical properties and molecular structure can be concluded：
[1] For three branched model molecules, the multiphoton absorption efficiency doesn’t show any dependence on the molecular symmetry, but the band position is slightly red-shifted for the asymmetric model compounds. As a structural unit, benzothiazole has a better enhancement on the multiphoton absorption efficiency compared to triazolopyridine.
[2] Both the addition of methoxy groups on the electron-donor sites and the insertion of carbon-carbon triple bond into the π-framework will promote molecular two-photon efficiencies of linear type model compounds. But for the enhancement of three-photon efficiency, only the later exhibits positive impact. This feature indicates that the structure requirements for the promotion of molecular two-photon and three-photon efficiencies may be different.
[3] For linear model compounds, multiphoton absorption efficiency can be promoted by extending π-conjugation length through the insertion of thiophene, fluorene and carbon-carbon double bond. In two-photon absorption, fluorene unit possesses larger positive impact within shorter wavelength region while thiophene unit can promote two-photon
efficiency at longer wavelength region. For three-photon efficiency, thiophene manifests greater overall enhancement at all wavelength compared to fluorene unit.
The second part of this thesis is the development of monomer which can be used in lithium batteries. This research project is supported by Industrial Technology Research Institute (ITRI, Taiwan). Liquid electrolyte nowadays used in lithium batteries has the risk of leakage and combustion. Our goal of this collaborating project is to replace liquid
electrolyte with solid electrolyte which has lesser safety concern but with the similar or better battery performance. Currently we has developed monomer ECMA. Proper amount of ECMA mixed with crosslinking agent THEA or GIA can reduced polarization when made into coin cell. When ECMA and THEA is made into 1Ah pouch cell, the performance of energy density, irreversibility and 0.2C discharging capacitance are matched with the performance of the cell only contains commercial liquid electrolyte 352. | en_US |