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Graphene possesses excellent mechanical strength and chemical inertness with high intrinsic carrier mobility and superior flexibility making them exceptional candidates for optoelectronic applications. Graphene quantum dots (GQDs) derived from graphene domains have been widely explored to study their photoluminescence properties which can be tuned by size. GQDs are biocompatible, low cytotoxic, strongly luminescent and disperse well in polar and non-polar solvents showing bright promise for the integration into devices for bioimaging, light emitting and photovoltaic applications. In the present study, graphene quantum dots were synthesized by an electrochemical cyclic voltammetry technique using reduced graphene oxide (rGO). GQDs have been incorporated into binder free TiO2 paste and studied as a photoelectrode material fabricated on ITO/PEN substrates for flexible dye sensitized solar cells (DSSCs). DSSC based on GQDs-TiO2 exhibited open circuit output potential difference (Voc) of 0.73 V, and short circuit current density (Jsc) of 11.54 mA cm-2 with an increment in power conversion efficiency by 5.48 %, when compared with those with DSSC build with just a TiO2 photoanode (open-circuit output potential difference (Voc) of 0.68 V and short circuit density (Jsc) of 10.67 mA cm-2). The results have been understood in terms of increased charge extraction and reduced recombination losses upon GQDs incorporation.

Binder free TiO2 paste is prepared using tert-butyl alcohol in dilute acidic conditions at room temperature for flexible polymer dye sensitized solar cells (DSSC). The present paper reports the detailed studies carried out to elucidate the importance of stirring times during the paste preparation on the final device performance. The maximum conversion efficiency of 4.2 % was obtained for flexible DSSCs fabricated on ITO/PEN substrates using TiO2 paste prepared from an optimum stirring time of 8 hours. The effect of optimum stirring times on the device characteristics has been understood in terms of the detailed morphology and surface area measurements.

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