Through billion years of evolution, Nature provided us with a myriad of materials with incredibly different colors, structures, and response to external stimuli such as thermal, mechanical or electrical. Nature could be the source of abundant and environmentally benign materials to be used in next generation electronics, paving a way towards a sustainable use of resources. At present, electrical and electronic devices use massive amounts of energy for their manufacturing. Human and environmentally benign natural materials and low-temperature fabrication processes are the first choice for a number of applications, including ubiquitous device networks in the Internet of Things.
Natural molecular materials are usually immersed in aqueous saline media such that their electrical response includes a significant ionic contribution. Depending on their molecular structures, natural materials can also feature electronic transport, on distance ranges that depend on their supramolecular aggregation and consequent p-p stacking.
Systematic investigation of structure-property relationships are needed to generate technologies based on natural materials in sustainable electronics. Because natural organic materials are complex in their chemical composition and molecular structure as well as charge transport mechanisms, comparative studies with well-defined chemically controlled analogues are imperative.
Our work focuses on eumelanin, a dark-brown subclass of redox-active melanin pigments, ubiquitous in animals and plants. Eumelanin, exhibits intriguing hydration-dependent electrical properties. It also possesses photoprotective, thermoregulative, metal ion chelating (ion binding affinity) and free radical quenching properties.
We report about how the eumelanin pigment (polymer) forms from building blocks (monomers) and how the structure of the pigment affects its electrical response, in view of the fabrication of eumelanin-based devices for energy storage (1-3). We also explore, in our studies, the biodegradability of materials and devices, in compost conditions.
(1) E. Di Mauro et al, MRS Communications 7, 141, 2017.
(2) P Kumar et al, JMCC, 4, 9516, 2016.
(3) A. Pezzella et al. 2, 212, 2014