Cornell University researchers are working on a way to reduce the cost and increase the efficiency of solar cells by building an organic framework using the same type of dyes that are used in blue jeans. These common organic dyes, called phthalocyanines, are very similar in structure to chlorophyll, which is the compound in plants that absorbs sunlight for photosynthesis. The Cornell researchers, lead by William Dichtel and Eric L. Spitler, have been able to assemble the dye molecules into a structure called a covalent organic frameworks or COFs. The COF is important because, while organic materials are currently being used in various solar cells, its been very difficult to “organize their component molecules reliably into ordered structures likely to maximize device performance.”
The COF uses a simple acid catalyst and stable molecules called protected catechols to create two dimensional sheets. In the Cornell design, these sheets can stack on top of each other to form a lattice that electrons can easily move through. The process is actually self correcting, which reduces cost. “The whole system is constantly forming wrong structures alongside the correct one,” Dichtel said, “but the correct structure is the most stable, so eventually, the more perfect structures end up dominating.” The phthalocyanine dye used absorbs light across almost the entire spectrum.
The COF structure itself isn’t actually the solar cell, its just the framework. But the researchers are confident that inexpensive, efficient and easy to manufacture solar cells could easily be created by filling the pores between the molecules in the lattice with other organic materials used in today’s organic solar cells.