Transforming flexible devices to stretchable oxide-based electronics, photonics, and sensors

Lightweight compact electronics are currently the most popular personal electronic devices. A trend towards wearable and body compatible smart devices is clearly indicated, creating the demand for electronics to be fully flexible and stretchable to realise next generation devices.

To allow for this additional degree of freedom, strategies for fabricating these devices need to be established. The fabrication of such devices pose a challenge to materials science due to the inherent brittle nature of metals, oxides and semiconductors, the core building block for powerful electronics. This thesis explores new methods of integrating these materials into flexible and stretchable platforms.

Initially a comprehensive study into metal films on flexible substrates is carried out with insights into strategies to reduce the sensitivity towards strain. Based on these insights, multilayer resonating terahertz structures on a flexible platform are presented and analysed, showcasing the ability to distinguish polarisation efficiently.
The integration of a functional material namely zinc oxide into a flexible platform is demonstrated by realising a visible-blind UV imaging array capable of operating in various bending states.

In order to enable an additional degree of freedom, strategies to enable stretchability of functional oxides is explored. A novel method of transferring high temperature processed oxides (indium tin oxide) is presented, to overcome process temperature limitations. Secondly, a phenomena named “micro-tectonics” which allows oxides to stretch and bend is discovered and analysed.

Based on the micro-tectonic effect zinc oxide stretchable devices are demonstrated that are capable of detecting UV and gases efficiently at room temperature which outperform their rigid counterparts. Additionally high refractive index contrast devices are shown that dynamically manipulate visible light via device deformation. Multifaceted analysis provides insight into the excellent tunability of these diffractive and resonating optical devices.

The thesis offers a cross-disciplinary insight into incorporation of functional oxide thin films with flexible and stretchable materials, and the potential for a new paradigm of functional devices.