Design of plasmonic solar cells combining dual interface nanostructure for broadband absorption enhancement

We propose an ultra-thin film solar cell structure combining front semicircular dielectric grooves and back trapezoidal metal reflector. The back trapezoidal metal structure traps light by the excitation of plasmonic modes and the outstanding scattering effect of our optimized shape to enhance the absorption at long wavelengths. The front groove structure boosts absorption at short wavelengths by the mechanisms of Fabry-Perot resonance, scattering and the interaction with back plasmonic structure. The total absorption efficiency over the entire spectrum in 100 nm thick active layer is as high as 78.4% under normal incident light and it can also be maintained in a high level even if the incident angle varies from −60° to 60°. Broadband absorption, efficiency enhancement and insensitivity to the angle indicate the dual interface nanostructure to be a practical reference.