Reduced graphene oxide and perylene derivative nanohybrid as multifunctional interlayer for organic solar cells

Abstract

In this work, reduced graphene oxide:3,4,9,10-perylenetetracarboxylic dianhydride nanohybrid was prepared by a modified Hummers method which resulted in effective functionalization of graphene sheets. In this procedure, the perylene molecules were included at the reaction medium of graphene oxide, where the acid promotes hydrolysis of the anhydride, forming carboxylic acids; these groups react with hydroxyl groups of graphene oxide, generating ester bonds between graphene oxide and perylene, followed by a reduction through thermal annealing in air. The resulting interfacial nanohybrid film combines optical and electrical features of both materials, being a promising functional interlayer in organic-inorganic based devices. Herein, the thin film was tested in organic solar cells; the photovoltaic response pointed out that the dipole character of the nanohybrid enhances the fill factor and open circuit voltage parameters, when compared with the solar cell without buffer layer or having a polymeric hole transporting layer. After that, the optimized solar cells displayed open circuit voltage of 0.76 V, short circuit current density of 11.61 mA/cm2, fill factor of 53 % and power conversion efficiency of 4.70 % under AM1.5 illumination, where the nanohybrid film may act as a complementary absorbing layer and as hole injection layer, pointing out the potential use of this compound to improve the photovoltaic response in solar cells.