Decrease of back recombination rate in CdS quantum dots sensitized solar cells using reduced graphene oxide

The photovoltaic performance of CdS quantum dots sensitized solar cells (QDSSCs) using the 0.2 wt% of reduced graphene oxide and TiO2 nanoparticles (RGO + TiO2 nanocomposite) photoanode is investigated. CdS QDs are adsorbed onto RGO + TiO2 nanocomposite films by the successive ionic layer adsorption and reaction (SILAR) technique for several cycles. The current density-voltage (J-V) characteristic curves of the assembled QDSSCs are measured at AM1.5 simulated sunlight. The optimal photovoltaic performance for CdS QDSSC was achieved for six SILAR cycles. Solar cells based on the RGO + TiO2 nanocomposite photoanode achieve a 33% increase in conversion efficiency (h) compared with those based on plain TiO2 nanoparticle (NP) photoanodes. The electron back recombination rates decrease significantly for CdS QDSSCs based on RGO + TiO2 nanocomposite photoanodes. The lifetime constant (t) for CdS QDSSC based on the RGO + TiO2 nanocomposite photoanode is at least one order of magnitude larger than that based on the bare TiO(2)NPs photoanode.