Single-layer graphene sheets as counter electrodes for fiber-shaped polymer solar cells

Abstract

A single-layer graphene sheet represents the thinnest transparent conductive electrode for planar photovoltaic devices on both rigid and flexible substrates. Here, we demonstrate fiber-shaped polymer solar cells wrapped by a Au nanoparticle-adsorbed graphene single-layer sheet as a counter electrode, and show cell efficiencies up to 2.53% under standard illumination, which can be improved to 4.36% when tested on a diffusive reflector. This is a relatively high efficiency reported for fiber solar cells using solid-state polymers as active layers. The graphene layer not only serves as a transparent flexible electrode for the fiber solar cells, but also provides good encapsulation on the polymer layers, resulting in excellent flexibility and device stability in both inertial gas and ambient atmosphere, with less than 5% efficiency degradation in air after 8 days. Single-layer graphene is a potential electrode material for constructing efficient and stable polymer fiber solar cells.