Double-sided TiO₂nano-gratings for broadband performance enhancement of organic solar cells

To achieve broadband performance enhancement of organic solar cells, a double-sided TiO2 circular nano-grating scheme has been applied to a typical cell using staircase-like layers. In fact, the top side grating results in efficient anti-reflection properties in the wavelength range of 300–655 nm owing to the gradual change of the refractive index and solving the impedance mismatch issue. Simultaneously, the bottom grating leads to light trapping in the long wavelengths (655–1100 nm) due to the excitation of guided mode resonances. The proposed structure yields a broadband, polarization insensitive, and angle-robust absorption enhancement, as well as an enhanced photocurrent of 15.97  mA/cm2.