Tunable optical properties of silicon nanowires for photovoltaic devices

Abstract

In recent times, silicon nanowires (Si-NWs) have been primarily used as an inorganic layer in producing hybrid solar cells, mainly because of their enhanced optical absorption characteristics. This study utilizes the metal-assisted chemical etching (MACE) technology to produce vertically aligned, long Si-NWs with a high aspect ratio. The role of metal nanoparticles in the MACE technique was investigated, and the structure optimization process was performed by altering the etching time. Observations indicate that the concentration of metal solution influences both the size and spacing of Si-NWs, whereas the etching time affects the length of the Si-NWs. The optical characteristics of the Si-NWs were also examined utilizing the experimental diffuse reflection spectra. In addition, a 3D finite difference time domain (FDTD) simulation was conducted to analyse and compare the absorption spectra of the created Si-NWs with the experimental findings. Systematic analysis of absorption as a function of the geometry of nanowires (NWs) indicates that as the length and the diameter increase it demonstrates notable anti-reflection properties. This can be attributed to the larger surface area of the NWs and increased roughness/disordered surface. Hence, the work concisely illustrates the essential significance of improved absorption of Si-NWs in attaining optimal efficiency in hybrid solar cell applications.