Plasmonics is the study of the interaction between electromagnetic field and free electrons in a metal, dielectric and semiconductor nanoparticle. Due to such interaction, the plasmonic particles can increase the path length of incident light. Optical path length into a solar cell is one of the most significant parameters for photon collection and conversion of them to short circuit current in the device. A major portion of light gets transmitted through the thin silicon substrate (< 30 µm) which is the main drawback of using such material in PV applications. For this reason, optically thick wafers (180–300 µm) are more suitable for solar cell fabrication. On the other hand, in case of thick silicon substrates, the carriers which are generated far away from the p–n junction, are unable to contribute to photocurrent generation due to bulk recombination process and material cost will be more compare to the thin substrate. However through this chapter authors going to established the fact that, by applying the plasmonic nanoparticles and metamaterials with optimized diameter and distribution, the path length of light in both thin and thick Si solar cells can be increased, which in turn gives better carrier generation and short circuit current.