Solar Absorber Surfaces Treated by Femtosecond Laser

Using a femtosecond laser surface structuring technique, we produce technologically important solar absorbers (black aluminum, titanium, tungsten, copper, and stainless steel) with absorptance of about 85-95% over a broad wavelength range from ultraviolet to infrared. Scanning electron microscopy shows that the enhanced absorption of the black metals is caused by a rich variety of nano- and microscale surface structures. The black metals produced in this study may find applications in solar energy absorbers, photovoltaic thermal collectors, and heat transfer devices. The suggested technique is environmentally friendly.