Absorbance enhancement of thin film solar cells with front double dielectric and back metallic grating

• The combination of a subwavelength aperture and a double nano-structured dielectric grating with back triangle metallic grating will result in an enhancement in total optical absorption.
• 90.85% Average harvesting can be achieved by the optimized structure in the spectrum range from 300 to 1100 nm.
• The high integrated absorption and is weakly dependent on incident angle.

We present finite difference time domain (FDTD) and rigorous coupled-wave analysis (RCWA) simulations to analyze the optical absorption enhancement of thin film solar cells (TFSCs) employing front double dielectric and back plasmonic grating structures. Simulation results show that the combination of a subwavelength aperture and a double nano-structured dielectric grating with back triangle metallic grating results in an enhancement in total optical absorption. The absorption of the planar structure is enhanced thanks to an increase of the optical path length of the red and near-infrared photons, causing a proportional enhancement of the absorption in this spectral range. 90.85% Average harvesting (on TE and TM) can be achieved by the optimized structure in the spectrum range from 300 to 1100 nm. The designed SC has high integrated absorption and is weakly dependent on incident angle, which should be useful for application in film photovoltaics, photodetectors and infrared imaging.