Improvement of Efficiency in CdS Quantum Dots Sensitized Solar Cells

CdS quantum dots were coated on $TiO_2$ layer by successive ionic layer adsorption and reaction method. An efficient photovoltaic energy conversion and significant quantum-size effect were observed. The magnitude of the short-circuit photocurrent density $J_{SC}$ was found to be approximately 6.01 $mA//cm^2$ for graphene oxide-incorporated $CdS//TiO_2$ solar cell, while the $J_{SC}$ of only CdS-sensitized solar cells was lower than 4.40 $mA//cm^2$. The efficiency of the $CdS//TiO_2$ solar cell with a graphene oxide layer containing CdS QDs was 60% higher than that of the $CdS//TiO_2$ solar cell. The cell efficiency was remarkably improved with the graphene oxide-incorporation. The carrier recombination of the QDs sensitized solar cells based on CdS-coated $TiO_2$ was significantly suppressed due to photogenerated charge carrier transports resulting from the presence of graphene oxide.