Novel application of atomic force microscopy to the analysis of barrier film defects

Bottomley, Joseph Anthony (2012). Novel application of atomic force microscopy to the analysis of barrier film defects. University of Birmingham. Eng.D.


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As a result of numerous advantages over glass based devices, flexible displays continue to gather momentum. Many problems associated with fabrication of devices on polymers have been overcome, but the detrimental effect of water permeation through these substrates due to defects is still prevalent despite attempts to block pinholes with thin film barrier materials. A rigorous study of film defects using atomic force microscopy (AFM) plus novel application of the calcium test, with additional scanning electron microscopy and white light interferometry data has been undertaken. While pursuing this study, new methods of displaying defect data were discovered, allowing the problem to be visualised better. In addition, the results demonstrated that the major cause of device failure was point defects in the barrier films caused by airborne dust which adheres to the film surface before application of the barrier. The calcium test was applied in new ways to demonstrate the damaging influence of these film defects. To explain the results, a new model of permeation was devised through quantative analysis of the defects present on industrially produced films and confirmed using model substrates and a synthetic model, to explain the behaviour observed in the literature, but never previously explained. The conclusion was that the combination of AFM study, calcium testing and theoretical modelling gave improved understanding of the defect problems in flexible display devices. It is expected that the findings of this work will help DuPont Teijin Films to eliminate such flaws from their manufacturing process, ultimately allowing the films to be applied to commercial applications.

Type of Work: Thesis (Doctorates > Eng.D.)
Award Type: Doctorates > Eng.D.
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Chemical Engineering
Funders: None/not applicable
Subjects: Q Science > QR Microbiology
T Technology > TP Chemical technology


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