▎ 摘　　要

The effects of the graphene doping level on the optical and electrical properties of ITO/P3HT:Graphene/Au solar cells are investigated. The spectroscopic ellipsometry (SE) analysis proves that the insertion of low graphene content in the P3HT matrix reduces the optical bandgap of the P3HT:Graphene nanocomposite and the thickness of the film. As a result the optical absorption properties of the device are enhanced in the visible range. The device elaborated with the lower graphene content displays a J(SC) = 9.93 x 10(-4) A/cm(2), a If V-OC = 0.55 V and FF = 41%, under illumination. These results are in good agreement with the SE analyzes since the device elaborated with the lower graphene content exhibits the higher optical parameters. The origin of the improved energy conversion efficiency for low graphene doping level is discussed in this work. (C) 2014 Elsevier Ltd. All rights reserved.