Photonic crystal based photoelectrochemical cell for solar fuels

Abstract

Abstract The solar fuel production efficiency of photoelectrochemical cells based on TiO2 is primarily limited by the low optical absorption coefficient and concomitant long penetration depth of visible light compared with the minority charge carrier diffusion length. A TiO2 photoelectrode consisting of a slanted conical‐pore photonic crystal immersed in water and integrated on a reflective back‐contact is proposed to reduce the light penetration depth by more than 10 times and branch the electron and hole transports into dimensions matching their diffusion lengths. This brings the photoelectrolytic process into the high‐efficiency operating regime. The maximum achievable photocurrent density for a lightly doped TiO2 with the imaginary part of the dielectric constant 0.01 in the visible range reaches 7.65 mA cm‐2.

Keywords

• light harvesting
• photoelectrochemical cell
• photonic crystal
• solar fuel