we suggest that a class of biological macromolecules called the melanins may be suitable replacements for the ruthenium complexes. They have strong, broad band absorption, are chemically and photochemically very stable, can be cheaply and easily synthesized, and are also bio-available and bio-compatible. We demonstrate a melanin-based regenerative solar cell, and discuss the key properties that are necessary for an effective broad band photon harvesting system. READ MORE HERE
…explore the possibilities of using bio-organic pigments with broad band light absorbing properties as the primary photon harvesting component. In this context, we will concentrate on a class of bio-macromolecules called the melanins, and will also highlight several other potential material. What will hopefully become clear during this discussion, is the need to understand the detailed photophysical and photochemical properties of these molecules, and how these properties relate to their chemical and electronic structure.It is also important to note that we will not deal in this chapter with the concept of creatingartificial photosynthetic membranes by immobilizing and assembling photofunctionalmolecules on various substrates – although this approach has the potential to create directconversion photovoltaic devices. (Broad Band Photon Harvesting Biomolecules for Photovoltaics)
In biological science melanin is known to possess a diverse set of roles and functions in a wide range of organisms. These include:
* Protection against biochemical attack: e.g. the smokeshield-like ink of the octopus, and the melanin-based protective colorings of bacteria and fungi which are capable of encapsulating and oxidizing invading organisms in a process known as melanization
* Mitigating chemical stresses associated with exposure to heavy metals and oxidizing agents.
* Acting as a natural sunscreen: shielding light-sensitive tissue from the potentially damaging effects of ultraviolet light. READMOREHERE
If melanin can convert light into heat, could it not also transform UV radiation into other biologically/metabolically useful forms of energy? This may no seem so far fetched when one considers that even gamma radiation, which is highly toxic to most forms of life, is a source of sustenance for certain types of fungi and bacteria. READMOREHERE