Laser Welding Enhances Dye-Sensitized Solar Cell Efficiency

A team of scientists at the Yonsei University has found that efficiency of a solar cell increases by a maximum of 65%, when the dye-sensitized solar cell (DSSC) interfaces are welded using laser.

DSSC having titanium dioxide (TiO₂) nanostructures feature good fill-factors, high open-circuit voltages, and better charge-collection potentials. However, the DSSC does not absorb all the near-IR and visible photons, As a result, it has less short-circuit photocurrent densities when compared to the traditional inorganic photovoltaics. Improving the DSSC’s short-circuit current density is vital for enhancing the optical-to-electrical effectiveness of the instruments.

Scientists from the Yonsei University’s Department of Materials Science and Engineering have showed that the inter-electrode contact resistance, which arises from the interfacial adhesion, is liable for a major portion of the DSSC’s total resistance. The scientists showed that the current flow can be enhanced by welding the DSSC interface with the use of a laser.

TiO₂ films formed on glass substrates, which are coated with transparent conducting oxide (TCO), are irradiated using a pulsed UV laser ray at a wavelength of 355 nm. This laser beam is absorbed by TiO₂. A continuous, thin TiO₂ layer is developed at the interface because of the melting of TiO₂ nanoparticles. The layer decreases the space between the two electrodes completely, and enhances the current flow by decreasing the contact resistance. The research group managed to enhance the efficiency of units by 35% to 65%.