The local surface plasmon resonance (LSPR) effects of metallic nanoparticles (such as light scattering and giant local field) in organic materials can improve the optical absorption capability of organic solar cells. This is especially important for polymer solar cells where the active layer thickness has been limited (< 150 nm) due to short electron-hole diffusion length. LSPR effects depend on the features of nanoparticle, such as shape and size. Qua cubic nanoparticle produces a stronger LSPR compared to other shapes and increased LSPR effect increases the light absorption. However, fabrication of the cubic nanoparticle is much more difficult compared to fabrication of spherical ones. This study aims to increase LSPR effects of spherical nanoparticles and we propose the SiO2@Au@SiO2 new structure for them. Our simulation results demonstrate increase in power absorption and short circuit current of similar to 103% and similar to 118%, respectively, with square array of SiO2@Au@SiO2 nanoparticles with central nanoparticle inserted in thin active layer compared to the structure without nanoparticles. Subsequently, we propose the new square array without central nanoparticle for SiO2@Au@SiO2 nanoparticles. Calculations show significant enhancement in power absorption and short circuit current of respectively similar to 136% and similar to 154%, compared to the structure without nanoparticles. These improvements are justified pursuant to enhanced light trapping inside the active layer.