Improving the Performance of Printable Carbon Electrodes by Femtosecond Laser Treatment

Low-cost carbon-conductive films were screen-printed on a Plexiglas(R)substrate, and then, after a standard annealing procedure, subjected to femtosecond (fs) laser treatments at different values of total accumulated laser fluence phi(A). Four-point probe measurements showed that, if phi(A)> 0.3 kJ/cm(2), the sheet resistance of laser-treated films can be reduced down to about 15 omega/sq, which is a value more than 20% lower than that measured on as-annealed untreated films. Furthermore, as pointed out by a comprehensive Raman spectroscopy analysis, it was found that sheet resistance decreases linearly with phi(A), due to a progressively higher degree of crystallinity and stacking order of the graphitic phase. Results therefore highlight that fs-laser treatment can be profitably used as an additional process for improving the performance of printable carbon electrodes, which have been recently proposed as a valid alternative to metal electrodes for stable and up-scalable perovskite solar cells.