Impact of Laser Wavelength on the Optical and Electronic Properties of Black Diamond

Black diamond, obtained by femtosecond laser treatment of natively transparent diamond, is a promising material for solar applications. The enhancement of the interaction between the active material and the solar spectrum is obtained by a controlled texturing of the diamond surface at the nanoscale, the impact of which on the optical and electronic properties of the bulk material is strongly influenced by the laser parameters. In this work, the properties of black diamond samples obtained by using two different laser wavelengths (400 and 800 nm) are compared, showing that texturing periodicity (80 and 170 nm, respectively) is strictly related to the laser wavelength used. Conversely, a unique optimal accumulated absorbed laser fluence (2.10 kJ cm−2) demonstrated to return the best results in terms of responsivity in the solar spectrum, regardless of the wavelength used for laser treatment. Black diamond is a brand new material, obtained by laser treatment of white diamond, with outstanding optical absorption properties. However, for solar energy conversion applications, it is necessary to improve its responsivity. This work compares the optoelectronic properties of black diamonds obtained with two different laser wavelengths (400 and 800 nm), showing that 800 nm is a better choice.