Date of Award

2015

Degree Type

Thesis

Department

Chemistry and Biochemistry

First Advisor

Tricia B Carmichael

Keywords

Applied sciences, Elastomeric emissive materials, Engineered crack propagation, Strain sensors, Stretchable conductors, Stretchable electronics, Stretchable light-emitting devices

Rights

CC BY-NC-ND 4.0

Abstract

This dissertation addresses three main challenges towards the fabrication of large-area stretchable electronic devices. First, we replaced expensive photolithography techniques with low-cost methods to achieve highly stretchable gold films on elastomers. Second, we enabled the fabrication of large-area stretchable pixels through the incorporation of stretchable elastomers in the emissive layer of light-emitting devices. Third, we made progress towards theinception of air-stable large-area stretchable electronics by developing methods to deposit conductive metal films on new highly impermeable stretchablesubstrates.

Chapter 2 describes the deposition of a low-cost, microstructured glue interlayer on an elastomeric substrate to enable the fabrication of gold films with high stretchability for use as device interconnects and strain sensors. The microstructured glue interlayer is low-cost, commercially available and green and can be deposited by benchtop fabrication processes eliminating the need for expensive photolithographic patterning techniques to achieve stretchable metal geometries.

Chapter 3 expands upon the work of Chapter 2 to develop a poly(vinyl alcohol) polymer interlayer whose tunable mechanical properties affect the crack propagation in overlying metal films. When the polymer is dry, it is a brittle film that cracks under strain and causes metal films to fail electrically at low elongations. After exposure to water condensation the polymer interlayer softens and a wrinkled topography develops which enables gold films to stretch to 75% elongation before failure occurs.

Chapter 4 reports the development of an elastomeric emissive material capable of withstanding strains up to 27% before light emission is no longer observed. This is the first example of a room-temperature stretchable large-area light-emitting device.

Chapter 5 builds upon the work of Chapter 4 by incorporating graft copolymers with increased air and moisture permeability into the emissive layer. We demonstrate that the graft copolymers provide greater device stability than the elastomer reported in Chapter 3 and can sustain repeated cyclic strains without influencing the peak radiance.

Chapter 6 presents methods to enable the deposition of conductive metal films on elastomers with high impermeability to water and oxygen. This is the first step to realizing commercial stretchable electronic devices capable of ambient operation.

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