Nanotubes could boost dye-sensitised solar cells
US researchers aim to improve dye-sensitised solar cells, using carbon nanotubes and conductive polymers to ease electron extraction.
This type of solar cell is easy to make, potentially flexible, but dogged by moderate efficiency.
Drexler University and the University of Pennsylvania have teamed up to boost efficiency by increasing cell conductivity.
“In order for a solar cell to generate an electric current, the photo-generated electrons in the photo-anode have to travel through the network of titanium dioxide nano-particles and they encounter many boundaries between particles during the transport,” said lead investigator Dr Daeyeon Lee, of the University of Pennsylvania. “Due to this random transit path for the electrons, a large fraction of them are lost in the particle network before they reach the indium tin oxide glass, thus failing to generate electric power.”
Adding carbon nanotubes, according to Lee, will provide uninterrupted pathways for the electrons.
Attempts will also be made to replace the electrolyte that carries electrons from the cathode to the anode inside the solar cell with a solid polymer.
Liquid electrolytes are convenient as they soak into the porous cell electrode to provide maximum contact.
However, they can leak and, according to Drexler, are not as conductive as some polymers.
“The solid polymer is going to reduce some of the major conversion losses in the cell by closing doors that lead to electron loss that takes place with using a runny liquid,” said Drexler researcher Dr Kenneth Lau. “Unlike the liquid, the polymer will not leak out of the cell and opens the door for making a flexible solar cell.”
Lau’s group claims to have a way to get the polymer into the sponge-like electrode.
“Simply put, rather than figuring a way to squeeze an already-solid polymer into the electrode, we have invented a method for making the polymer inside the electrode,” said Lau.
The whole cell will be extensively computer modelled
“Our ultimate goal is to design and test a highly efficient dye-sensitised solar cell array through computational optimal design, synthesis and integration,” said Dr Masoud Soroush who heads the Drexler team.