Nanostructured multilayer graded-index antireflection coating for Si solar cells with broadband and omnidirectional characteristics

TLDR

The study designs, fabricates, and characterizes a broadband, omnidirectional graded‑index antireflection coating composed of nanostructured low‑index silica deposited by oblique‑angle deposition. The coating is fabricated by depositing nanostructured silica layers with refractive indices ranging from 1.05 to 1.40 via oblique‑angle deposition to form a three‑layer graded‑index structure. Polished silicon reflects about 37 % of incident light over 400–1100 nm and 0°–90° incidence, but the three‑layer graded‑index AR coating reduces reflection losses to 5.9 %, matching theoretical predictions and demonstrating applicability to photovoltaic cells of any material.

Abstract

Design, fabrication, and characterization of a broadband, omnidirectional, graded-index antireflection (AR) coating made using nanostructured low-refractive-index (n=1.05–1.40) silica deposited by oblique-angle deposition are reported. Averaged over wavelength range from 400 to 1100 nm and 0°–90° angle of incidence, polished Si reflects ∼37% of incident radiation. The reflection losses are reduced to only 5.9% by applying a three-layer graded-index AR coating to Si. Our experimental results are in excellent agreement with theoretical calculations. The AR coatings reported here can be optimized for photovoltaic cells made of any type of material.