Experimental and numerical results concerning the influence of silver nanoparticles on the optical absorption of organic devices are presented. The metallic nanoparticles (NPs) are placed inside an interpenetrated poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) layer using a physical vapor deposition technique. An absorption enhancement by comparison to devices without NPs is shown. An increase of the absorption by annealing is also observed. Moreover, calculations are performed via a numerical analysis based on a Finite Difference Time Domain (FDTD) method. We demonstrate that the light absorption can mainly occur inside the active layer instead of inside the metallic NPs.