Efficiency enhancement of Cu(In,Ga)Se2 thin film solar cells by employing onmi‐directional ZnO nanostructure with MgF2 anti‐reflection‐coating layer

An omni‐directional, graded‐index, and textured ZnO nanorods (n = 1.7‐2.0) with MgF2 (n = 1.37) antireflection (AR)‐coating layer for Cu(In,Ga)Se2 solar cells grown by hydrothermal method are presented. We achieve that the graded index structure can reduce a weighted global reflectance of 5.5%, and significantly improve a current density (JSC) of Cu(In,Ga)Se2 solar cells up to 32.3 mA/cm2 which is comparable to a general MgF2 single layer AR coating. Optimized AR‐coating layer leads to decreasing Fresnel reflection by gradient refractive index between ZnO nanorods and air. According to our experiment results, ZnO nanostructure with MgF2 AR‐coating layer can be used for various photovoltaic cells to enhance the light conversion efficiency.