Melanin-Based Thin Films for Sustainable Electronic Devices

Abstract

Melanin is a natural (bio-sourced) and bio compatible material, attracting attention because of its physicochemical properties. Melanin is a family of pigments and the brown-black eumelanin pigment is part of this. It can be found in skin, hair, eyes, and brain [1-2]. Considering its quinone-based and conjugated molecular structure, eumelanin is an interesting candidate for bioelectronics. Transport physics in eumelanin-based thin films and pellets need to be better understood to optimize its technological applications. The main challenge for the use of eumelanin in bioelectronics is to increase the conductivity and detailed study is required to clarify and quantify the electronic and protonic contribution to charge transport.High quality thin films of eumelanin material on substrates such as ITO (Indium Tin Oxide) and FTO (Fluorine Tin Oxide) substrates were prepared to study the electronic transport properties of the biopigment. The electrodeposition method, spray pyrolysis, and spin coating were used for the preparation of uniform thin films. The structural, optical, and morphological properties of these thin films were studied using X-ray diffraction (XRD), atomic force microscopy (AFM), field emission electron microscopy (FESEM) and transmission electron microscopy (TEM). For the metal contacts both top contacts using a through shadow masking and photolithography were used. Preliminary results on the dependence of electronic transport on temperature, relative humidity, and interelectrode distance range were collected.Reference[1] Julia Wunsche, Yingxin Deng, Prajwal Kumar, Eduardo Di Mauro, Erik Josberger, Jonathan Sayago, Alessandro Pezzella, Francesca Soavi, Fabio Cicoira, Marco Rolandi, and Clara Santato, Chem. Mater. 2015,27, 436−442.[2] Prajwal Kumar, Eduardo Di Mauro, Shiming Zhang, Alessandro Pezzella, Francesca Soavi, Clara Santato and Fabio Cicoira, J. Mater. Chem. C, 2016, 4, 9516.