Cornell University researchers have discovered using molecules commonly found in blue jean and ink dyes could lead to more economical and flexible solar cells.
William Dichtel, assistant professor of chemistry and chemical biology, and Eric L. Spitler, a National Science Foundation American Competitiveness in Chemistry Postdoctoral Fellow at Cornell, have used a technique that utilises organic dye molecules, called phthalocyanines, and assembles them into a structure known as a covalent organic framework (COF).
A simple acid catalyst and relatively stable molecules called protected catechols are used to assemble key organic molecules into a neatly ordered two-dimensional sheet that are stacked on top of one another to form a lattice that provides charging pathways. The reaction also allows for errors in the process to be reversed, then corrected so eventually the more perfect structures become dominant.
Organic materials have gained a great deal of research attention for their potential in creating thin, flexible and low-cost solar cells, but one of the major difficulties has been organising their component molecules reliably into ordered structures; required to maximise efficiency and performance.
What makes the phthalocyanine dye molecules so well suited to solar cell applications is they absorb almost the entire solar spectrum – a trait the researchers say is a rare property for a single organic material. Phthalocyanines are closely related in structure to chlorophyll, the substance in plants that absorbs sunlight for photosynthesis, which produces energy.
The structure by itself is not a solar cell yet, but it is an important development that will significantly broaden the range of materials that can be used in COFs.
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