In recent years and in alternative to silicon and other inorganic semiconductors, a comprehensive study has been performed on organic semiconductor materials, based on conjugated polymers and conjugated small organic molecules.
Chief characteristic of all these compounds, mainly made of carbon and hydrogen, is the conjugation: the carbon hybridization allows the formation of molecular orbitals, where electrons are delocalized and shared in the entire molecule. These electrons, linked more weakly than others, determine the molecule properties.
In solid state, this type of compound can bring to semiconductor materials specific properties which, defined during the basic molecular engineering design, may vary according to the chemical composition of the molecule and according to its order degree .
By using the right chemical synthesis, it is possible to produce molecules and semiconducting materials with predetermined characteristics - such as colour or electric conductivity – that can be selected according to the target application.
Given the similarities with existing natural molecules, such as chlorophyll, carotene and/or haemoglobin, small conjugated molecules, worthy for electronic applications such as organic semiconductor materials, can be obtained through biotransformation. This is possible by modifying some selected microorganisms so that they can produce, from scrap available biomass, the required molecules without competing with food chain scrap, such as vegetable scraps or whey.