Optimum surface condition for plasmonic Ag nanoparticles in polycrystalline silicon thin film solar cells

Abstract

Excitation of surface plasmons in silver nanoparticles is a promising method for increasing the light absorption in solar cells and hence, the cell photocurrent. The optical environment is an important key factor to consider when designing plasmonic solar cells because it affects the surface plasmon characteristics. In this paper, we applied the silver nanoparticles on the rear side of polycrystalline silicon thin film solar cells and systematically investigated the optimum surface condition for maximising plasmonic enhanced light absorption in the cells. Three different environments, thermal silicon dioxide (SiO2), native SiO2, and oxide-free silicon surface were investigated. We found that the existence of the SiO2 layer between Si and nanoparticles has a major effect on Qscat and therefore, the absorption in the cells. We also found that nanoparticles on the thermal SiO2 layer showed that the peak of Qscat is located at the visible light wavelengths <700 nm, nanoparticles on the native SiO2 layer and directly on Si sample showed that their peaks of Qscat are positioned at the longer wavelengths >700 nm. The sample with nanoparticles on the native SiO2 layer showed the highest potential short circuit current density (Jsc) enhancement, 62.5%, and absolute Jsc enhancement, 32.3%. On the other hand, the sample with nanoparticles on the thermal SiO2 layer indicated 19.6% enhancement of Jsc.