Self‐Cleaned Photonic‐Enhanced Solar Cells with Nanostructured Parylene‐C

Abstract

AbstractPhotonic front‐coatings with self‐cleaning properties are presented as means to enhance the efficiency and outdoor performance of thin‐film solar cells, via optical enhancement while simultaneously minimizing soiling‐related losses. This is achieved by structuring parylene‐C transparent encapsulants using a low‐cost and highly‐scalable colloidal‐lithography methodology. As a result, superhydrophobic surfaces with broadband light‐trapping properties are developed. The optimized parylene coatings show remarkably high water contact angles of up to 165.6° and extremely low adhesion, allowing effective surface self‐cleaning. The controlled nano/micro‐structuring of the surface features also generates strong anti‐reflection and light scattering effects, corroborated by numeric electromagnetic modeling, which lead to pronounced photocurrent enhancement along the UV–vis–IR range. The impact of these photonic‐structured encapsulants is demonstrated on nanocrystalline silicon solar cells, that show short‐circuit current density gains of up to 23.6%, relative to planar reference cells. Furthermore, the improvement of the devices' angular response enables an enhancement of up to 35.2% in the average daily power generation.