Defence of doctoral thesis: Van Chinh Tran – Wood Templated Organic Electronics

In today’s digital era, electronics are now integral to most activities in our daily lives, offering swift and global communication, powerful data processing tools and advanced sensor devices. However, there are drawbacks to the exponentially growing demand for electronics, such as the depletion of fossil resources, and the complexities sur-rounding recycling electronic waste (E-waste). As we gradually step into the era of sustainability, it is necessary to explore alternative resources and develop greener electronic technologies. For this purpose, organic electronics (OE) has emerged as an interesting alter-native, owning to its potential for low-energy fabrication and use of organic materials composed of Earth-abundant elements.

The term “organic electronics’’ has been used widely to refer to electrical devices crafted from organic materials, typically semiconducting polymers. This arises from the fact that most developed OE de-vices such as solar cells, transistors, supercapacitors, and batteries are centered around such materials. Along with the development of different semiconducting polymer varieties, materials from various natural resources have also been explored for devices’ electrodes, binders, and electrolytes. Among them, materials from the forest have emerged as abundant, renewable, and valuable options. For many years, wood has been tailored and utilized as a device template, while its components including cellulose fibrils and lignin have been widely used as structural or active components in OE. Lignin has now become an important electrode and electrolyte active mate-rial in energy storage devices.

This thesis presents new approaches and findings in the utilization of woodand lignin as active components in different OE applications. The thesis centers around two primary themes, in which the first involves the development and utilization of conductive wood, containing lignin, and lignin nanoparticles (LNPs) for supercapacitors and battery applications.

The second theme focuses on developing and employing conductive wood as an active electrode in the creation of a wood electrochemical transistor.

Within the first theme, we have uncovered the potential of storing electricity in wood utilizing its redox-active component, native lignin. The discovery is reinforced by the successful employment of LNPs as active materials in an organic battery. Within the second theme I have demonstrated the world’s first wooden transistor, characterized its electronic performance and discussed the pretreatment procedure of the wood substrate that is necessary for achieving a working de-vice. This thesis is anticipated to contribute to new and valuable knowledge for encouraging the development of low-cost and sustainable OE in the future.

Keywords: Organic electronics, Wood, Lignin, supercapacitor, battery, organic electrochemical transistor (OECT).