Modeling and Characterization of Antireflection Coatings with Embedded Silver Nanoparticles for Silicon Solar Cells

Plasmonics applied to solar cells is a widely investigated research field. Its main purpose is to include plasmonic structures in the cell design, in order to increase light trapping in the cell and, consequently, its energy conversion efficiency. Light scattering by plasmonic structures has been extensively studied by depositing metal nanoparticles on both sides of the cell, in order to enhance the transmission into the cell and/or the path length of the transmitted radiation. The effects due to the nanoparticles were studied also in the presence of dielectric layers covering the cell and working as anti-reflective coatings (ARC), although a complete discussion on the possible optimization of this setup is lacking. In this work, we provide a joint computational and experimental investigation of the optical properties of silver nanoparticles embedded in a SiO (2) ARC located on top of a crystalline silicon wafer. The effect of the particle size, particle position within the ARC layer, and surface coverage on the light transmitted to the silicon crystal are simulated by a finite-difference time-domain (FDTD) in-house software. On the experimental side, a composite anti-reflective structure, made of a silica layer with embedded silver nanoparticles, is deposited on top of silicon wafers. Samples differing in the size and position of the embedded metal particles are produced. For each configuration, the total reflectance is optically measured by means of a photo spectrometer coupled to an integrating sphere. We provide direct comparison of experimental and simulation results, along with an exhaustive discussion about the transmission efficiency of the investigated systems. We also discuss how our analysis might be extended to different configurations and cell design.