CuS nano flakes and nano platelets as counter electrode for quantum dots sensitized solar cells

• The surface morphology is influenced by the seed layer and the position of the substrate.
• CuS films show intraband transition.
• Horizontal position coated unseeded CuS films show better electrocatalytic activity.
• Seed layers assisted growth is limiting the electrocatalytic activity.

A facile chemical bath deposited (CBD) CuS nanoflakes and nano platelets are used as an effective counter electrode (CE) for quantum dot sensitized solar cells (QDSSC) and the effect of seed layer assistance has been discussed. The CuS thin films used as CE exhibit intraband transitions in the longer wavelength region with direct band gap and the surface exhibits unique morphology depending upon the seed layer. The photovoltaic performance of TiO2/CdS/CdSe/ZnS cascade QDSSC with CuS as CE prepared at 60 °C shows increased electrocatalytic activity in polysulfide electrolyte with higher short- circuit current density, open circuit voltage, fill factor and a conversion efficiency of 4.02%.