Anomalous evolution of broadband optical absorption reveals dynamic solid state reorganization during eumelanin build-up in thin films.

ABSTRACT: The origin of eumelanin optical properties remains a formidable conundrum preventing a detailed understanding of the complex photo-protective role of these widespread natural pigments and the rational design of innovative bioinspired materials for optoelectronic applications. Here we report the unusual kinetic and thickness-dependent evolution of the optical properties of black eumelanin polymers generated by spontaneous aerial polymerization of 5,6-dihydroxyindole (DHI) thin films (0.1-1 μm), consistent with peculiar solid state reorganization mechanisms governing broadband absorption. The complete reversal of eumelanin UV-visible transmittance spectrum curvature on passing from 0.2 to 0.5 μm thick films, the marked increase in visible extinction coefficients with increasing film thicknes

SUBMITTER: Bonavolonta C 

PROVIDER: S-EPMC5428701 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature