Surface nanoscale texturing by ultrashort laser pulses to enhance solar absorbance

R&D activity in solar energy conversion is continuously seeking methods for increasing interaction of materials with the solar radiation. Ultrashort laser pulses in the fs range impinging on solids demonstrated to be effective in producing surface nanotextured structures with a periodicity depending on the laser wavelength. A spatial periodicity comparable with the solar spectrum wavelength is suitable for enhanced coupling phenomena, thus inducing a drastic increase in solar absorbance (up to values >90% [1,2]). We report on fs laser texturing performed on ultra-refractory ceramics, to be used as efficient radiation selective absorbers in solar concentrating systems [3], and on CVD diamond [4], to be used as defect-engineered semiconductor for high-temperature solar cells operating with electron emission. Finally, other applications and properties of surface-modified solids with ultrashort laser pulses will be discussed.