Graphene-based functional materials for organic solar cells [Invited]

Graphene is of great interest for future applications in organic photovoltaics (OPVs) due to its high three-dimensional aspect ratio, large specific surface area, remarkable optical transmittance, extraordinary thermal response, excellent electron/hole transport properties, superior mechanical stiffness and flexibility. Graphene-based functional materials can be used as transparent window/counter electrodes, interface layers, hole/electron transport materials and can also function as buffer layers to retard charge recombination in OPVs. Future work would focus on the following aspects: (a) design and preparation of novel graphene-based functional materials with good stability, high transparency and excellent conductivity for OPVs; (b) development of the new approaches that constitute a significant advance toward the production of graphene-based transparent conductive electrodes in OPVs; (c) evaluation on the long terms stability of devices with GO based modifying layers; (d) delicate control of unique graphene nanostructures; and (e) interface engineering of the graphene in terms of modifying its work function and surface free energy.