The Effect of Graphene/Ag Nanoparticles Layer on the Performances of Organic Solar Cells

Abstract

Graphene/Ag nanoparticles (GAg) were fabricated via a facile method, employing graphite oxide as a precursor of graphene (GNS), AgNO3 as a precursor of Ag nanoparticles, and sodium citrate as a reducing and stabilizing agent. We synthesized three kinds of GAg and denominated as GAg-1、GAg-2 and GAg-3. Graphene exhibits good electron conductivity, thermal conductivity, chemical stability and mechanical strength. We investigated the effect of inserting Graphene/Ag nanoparticles between hole transfer layer (HTL) of poly (ethylene dioxythiophene) (PEDOT)-polystyrene sulfonic acid (PSS) (PEDOT:PSS) and active layer (P3HT:PCBM =1:1 weight ratio) on the characteristics of polymer solar cell. The cell structure was ITO/PEDOT:PSS/GAg/P3HT:PCBM/Ca/Al. The concentration of Graphene/Ag nanoparticles solution was 2.0 mg/ml and the GAg nanoparticles layer was coated by spin-coating at 6000 rpm. We studied the effect of GAg layer addition on the photovoltaic performance. We used the UV-Vis, SPM, FE-SEM and solar simulator to measure the absorbance, roughness, surface morphology, and power conversion efficiency (PCE), respectively. From these results, we found that the short circuit current density (Jsc), fill factor (FF) and PCE of the cells with GNS or GAg were always higher than those of cell without GNS or GAg. The cell with GAg-2 had the highest short circuit current density (Jsc) of 9.14 mA/cm2, an increase of 28.4%, highest fill factor (FF) of 0.65, an increase of 32.7% and highest PCE of 3.82%, an increase of 71.3% when compared to standard device with active layer of P3HT:PCBM =1:1. These improvements were due to the high carrier mobility of graphene.