Non-uniform Al2O3 back reflector for performance enhancement of thin rear passivated silicon solar cells

Abstract Low material usage, physical flexibility, portability, and lightweight applications are some of the major advantages that have claimed serious research attention towards ultrathin crystalline silicon wafer-based solar cells. This work seeks to address a major challenge for such cells namely poor light absorption in thin absorbers. A novel inclined back reflector layer (BRL) of aluminium oxide for both planar and textured surfaced silicon devices with a thickness of 20 µm is investigated, combined with the passivation properties of the metal oxide film. A study of symmetric, asymmetric, and textured conformal BRL revealed an optical gain of ~32% for the optimized BRL as compared to the structure without BRL. The combined effect of passivation and back reflection of the proposed BRL improved the power conversion efficiency by 60%. The optical and efficiency gain of 17% was observed for the structures with inclined BRL, as compared to that of a planar BRL. A remarkable omnidirectional response was also observed for textured BRL structures.