| We demonstrate efficiency improvement in polymer solar cells (PSCs) by _22% through incorporating Au nanoparticles (NPs) into solar cells. Our theoretical result shows that the absorption enhancement at the active layer is attributed to plasmon resonances with strong near-field distributions penetrated into absorption polymers. These findings can be applied to design high-efficiency metallic NPs-incorporated PSCs.. A thin layer of ultraviolet-ozone (UVO) treated gold (Au) is introduced on multi-layer graphene (MLG) to enable the MLG as an effective anode for polymer solar cells (PSCs). Further analysis shows that UVO treated Au provides favorable band alignment at the MLG/polymer interface. Moreover, the improved interfacial contact and shortened UVO durations reduce the series resistance of PSCs significantly. |