Process Optimization of P(VDF-TrFE)-BaTiO3 Nanocomposites for Storage Capacitor Applications

Handle URI:
http://hdl.handle.net/10754/136957
Title:
Process Optimization of P(VDF-TrFE)-BaTiO3 Nanocomposites for Storage Capacitor Applications
Authors:
Almadhoun, Mahmoud N.
Abstract:
Increasing demands for efficient energy storage in microelectronics has pushed the scientific community towards finding suitable materials that can effectively deliver high pulse power in miniaturized systems. Polymer-ceramic composites are considered to be one possible solution towards the fabrication of high energy density capacitors, whether as embedded capacitors or gate insulators in organic field effect transistors (OFETs). Selecting high permittivity ceramics mixed with polymers with high breakdown field strengths would be the wisest approach towards enhancing energy storage. As such, novel ferroelectric polymers such as P(VDF-TrFE-CTFE) are being developed and researched, all displaying record dielectric values (K > 50) as promising candidates for high energy density composite capacitors (> 25 J/cm3). However, much work is still needed to understand the interaction mechanisms between the phases. We aim to seek an understanding of the processing challenges, especially in terms of fabricating thin film ferroelectric polymers and their application in nanocomposite capacitors while effectively maintaining optimized performance when embedded in flexible electronics. A process for synthesizing high performance P(VDF-TrFE) thin films is developed realizing the importance of controlling several process parameters to achieve high quality devices. Electrical and physicochemical characterization demonstrate how the performance of the polymer films improves with prolonged annealing periods by allowing sufficient time for solvent evaporation, crystallization and preferential-orientation of the crystallites. The polymer P(VDF-TrFE) is then used as a host material with barium titanate (BTO) nanoparticles below 100 nm (K = 150) as a ceramic filler in nanocomposite films. Facile surface modification by hydroxylation proved to be essential in the performance of the devices in terms of leakage current. A decrease of approximately 2 orders of magnitude in current leakage is recorded in surface modified BTO displaying potential for higher breakdown strength. Besides developing a process for P(VDF-TrFE) and low leakage composites, the importance of dispersion techniques and filler loadings are also discussed. Combining higher BTO volume fractions dispersed via colloidal milling enhances the effective permittivity by ~112% and lowers energy dissipation to a maximum of 0.1 at higher frequencies (1 MHz).
Advisors:
Alshareef, Husam N.
Committee Member:
Amassian, Aram ( 0000-0002-5734-1194 ) ; Schwingenschlögl, Udo ( 0000-0003-4179-7231 )
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Materials Science and Engineering
Issue Date:
11-Jul-2011
Type:
Thesis
Appears in Collections:
Theses; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorAlshareef, Husam N.en
dc.contributor.authorAlmadhoun, Mahmoud N.en
dc.date.accessioned2011-07-26T11:06:18Z-
dc.date.available2011-07-26T11:06:18Z-
dc.date.issued2011-07-11en
dc.identifier.urihttp://hdl.handle.net/10754/136957en
dc.description.abstractIncreasing demands for efficient energy storage in microelectronics has pushed the scientific community towards finding suitable materials that can effectively deliver high pulse power in miniaturized systems. Polymer-ceramic composites are considered to be one possible solution towards the fabrication of high energy density capacitors, whether as embedded capacitors or gate insulators in organic field effect transistors (OFETs). Selecting high permittivity ceramics mixed with polymers with high breakdown field strengths would be the wisest approach towards enhancing energy storage. As such, novel ferroelectric polymers such as P(VDF-TrFE-CTFE) are being developed and researched, all displaying record dielectric values (K > 50) as promising candidates for high energy density composite capacitors (> 25 J/cm3). However, much work is still needed to understand the interaction mechanisms between the phases. We aim to seek an understanding of the processing challenges, especially in terms of fabricating thin film ferroelectric polymers and their application in nanocomposite capacitors while effectively maintaining optimized performance when embedded in flexible electronics. A process for synthesizing high performance P(VDF-TrFE) thin films is developed realizing the importance of controlling several process parameters to achieve high quality devices. Electrical and physicochemical characterization demonstrate how the performance of the polymer films improves with prolonged annealing periods by allowing sufficient time for solvent evaporation, crystallization and preferential-orientation of the crystallites. The polymer P(VDF-TrFE) is then used as a host material with barium titanate (BTO) nanoparticles below 100 nm (K = 150) as a ceramic filler in nanocomposite films. Facile surface modification by hydroxylation proved to be essential in the performance of the devices in terms of leakage current. A decrease of approximately 2 orders of magnitude in current leakage is recorded in surface modified BTO displaying potential for higher breakdown strength. Besides developing a process for P(VDF-TrFE) and low leakage composites, the importance of dispersion techniques and filler loadings are also discussed. Combining higher BTO volume fractions dispersed via colloidal milling enhances the effective permittivity by ~112% and lowers energy dissipation to a maximum of 0.1 at higher frequencies (1 MHz).en
dc.language.isoenen
dc.titleProcess Optimization of P(VDF-TrFE)-BaTiO3 Nanocomposites for Storage Capacitor Applicationsen
dc.typeThesisen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberAmassian, Aramen
dc.contributor.committeememberSchwingenschlögl, Udoen
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.nameMaster of Scienceen
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