Hydrothermal synthesis of reduced graphene oxide‐anatase titania nanocomposites for dual application in organic solar cells

Lately, there has been increased interest in the design of graphene-based hybrid nanomaterials and their application to modify properties of organic solar cells (OSCs). Herein, we demonstrate an efficient route for the successful hydrothermal synthesis of reduced graphene oxide-anatase titania (RGOT) nanocomposites. Five nanocomposites with different titania concentrations, that is, RGOT-50, RGOT-75, RGOT-86, RGOT-90, and RGOT-92, were prepared. The nanocomposite RGOT-92 with the overall best properties was used to modify both the photoactive layer (P3HT:PCBM:RGOT) and hole transport layer (PEDOT:PSS:RGOT) of an OSC so as to assist in solar energy absorption by way of enhancing optical absorption and creating an efficient charge transport channel. The nanocomposites prepared consist of highly crystalline, spherical, and uniformly shaped TiO2 nanoparticles, with an average particle size of approximately 3.0 nm, deposited on the basal plane of reduced graphene oxide. Also, the nanocomposites show much reduced bandgap energies and low rates of electron-hole recombination. The incorporation of RGOT in the active layer effectively improved photon absorption, leading to high photoexciton generation. In addition, effective exciton dissociation was energetically favoured in the RGOT-modified hole transport layer (HTL), which concurs with the observed enhanced conductivity of the medium. Thus, the integration of RGOT in the active layer and HTL remarkably resulted in a high short-circuit current density (Jsc), low sheet resistance (Rs), and, consequently, improved photovoltaic performance. An enhanced photocurrent was noted, as high as 13 mA cm−2, from the OSCs by inlaying RGOT in the photoactive layer. An increased power conversion efficiency of up to 64% was achieved by the incorporation of RGOT in the photoactive layer. Thus, the utilized hydrothermal synthesis route provided nanocomposites with enhanced photoelectronic properties, with promising applications in nanoelectronic devices.