Browsing by Author "Usman, Muhammad"

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Highly hydrophobic metal-organic framework for self-protecting gate dielectrics
(2020-06-28)
Inamdar, Arif I.
;
Pathak, Abhishek
;
Usman, Muhammad
;
Chiou, Kuan-Ru
;
Tsai, Pei-Hsien
A hydrophobic metal-organic framework (MOF) showing high-kappa behaviour was synthesized by the reaction of copper ions with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (HFDPA). The unique, highly hydrophobic nature of the material protects it from re-adsorbing water, even in a high humidity environment. The dielectric constant of the MOF showed an unprecedented increasing trend, reaching up to kappa approximate to 99 at 300 K and 1 kHz after the complete removal of guest and coordinated water molecules. The unusual dielectric behaviour of the compound along with its water resistant properties is the first report of such behaviour and it paves the way for the development of moisture-stable microelectronic devices.
Zr-MOF/Polyaniline Composite Films with Exceptional Seebeck Coefficient for Thermoelectric Material Applications
(2019-01-23)
Lin, Chih-Chien
;
Huang, Yi-Chia
;
Usman, Muhammad
;
Chao, Wen-Hsuan
;
Lin, Wei-Keng
Controlling the polymerization of aniline in the presence of zirconium-based metal-organic frameworks (Zr-MOFs) using polystyrene sulfonic acid as a dopant resulted in the formation of a new type of freestanding thermoelectric composite film. Polyaniline chains interpenetrate into the Zr-MOFs to enhance the crystallinity of polyaniline, resulting in an improved degree of electrical conductivity. In addition, the inherent porosity of the Zr-MOFs functions to suppress the increase in thermal conductivity, thus dramatically promoting a negative Seebeck coefficient. When 20 wt % Zr-MOF was used, a power factor of up to 664 mu W/(m K-2) was obtained, which was accompanied by a surprisingly large, negative Seebeck coefficient. The new class of MOF-based composites offers a new direction for developing new types of efficient thermoelectric materials.