Modified Hummer’s method was adopted for the preparation of graphene oxide (GO) using graphite flakes. Graphene-oxide was incorporated in the TiO₂ paste and the films are prepared by screen printing on FTO glass (TEC8) substrates. The screen printed films were subjected to heat treatment cycle at 375°C for 5 min, 375 °C for 5 min, 450°C for 15 min and finally at 500°C for 15 minutes. The crystallinity and phase purity of the GO samples were characterised by X-ray diffraction using Cu-Kα radiation. The morphology of the GO is investigated using transmission electron microscopy and the chemical structures of GO are analysed by XPS.

Photovoltaic properties were measured by a computer-controlled digital source meter (Keithley 2400) under simulated one sun illumination at AM 1.5G (100mW/cm²) from a solar simulator (92250 A, Newport, USA). The electrochemical impedance spectroscopy (EIS) is carried out using Metrohm Autolab in the frequency range of 1MHz to 0.1Hz with amplitude of 20 mV under dark conditions. The device was assembled by coupling GO-TiO₂ films soaked in N719 dye with Surlyn as the spacer between the electrodes. The performance of the GO-TiO2 composite photoelectrodes were tested with different compact layers and different counter electrodes. The DSSC fabricated with graphene oxide as counter electrode exhibited photoconversion efficiency of 4.6% whereas, platinum based devices showed photoconversion efficiency of 4.7%. The present study suggests that graphene oxide counter electrodes can be considered as a promising alternative to platinum, with further optimisation, which clearly has advantages in terms of its abundance and low cost processing towards industrial prospects.