An integrated antireflection design using nanotexture and high-refractive-index glass for organic photovoltaics

We propose a new antireflection (AR) design for organic photovoltaics (OPVs) to achieve broadband and omnidirectional enhancement of photocurrent. In the proposed design, a hybrid AR structure, which combines moth eye texturing and two-layer interference coating, is integrated with a glass substrate having a high refractive index (n). Using the optical simulation for OPV cells, we compare the performance of various AR configurations upon changing the refractive index of the glass substrate. We show that the short-circuit current density (J_{S C}) is decreased by using the high-n glass substrate without AR coating, whereas J_{S C} is significantly increased by applying the high-n glass substrate with the hybrid AR structure, suggesting an importance of the integrated design. In addition, we demonstrate that the proposed AR configuration is quite effective to attain broad angle performance and is robust against the variations in geometric features of moth eye texture. Finally, the spectral dependence of photocurrent generation is experimentally measured for the verification of the effectiveness of the integrated AR design. These results provide a practical and efficient AR technique that can further expand the potential of OPVs as energy supply devices.