The development of high performance and cost-effective counter electrode (CE) is a persistent objective in order to convey the quantum dot sensitized solar cell (QDSSC) from laboratories to markets benches. In the current study, we present a simple two-step approach for fabricating a highly efficient CE for QDSSC composes from copper sulfide (CuS) nanoparticles and reduced graphene oxide (RGO) mixture. The two-step approach gave us the opportunity to synthesis pure cupric sulfide (CuS) nanoparticles; in the first step and with smaller particle size before mixing with graphene. In the second step, different ratios from CuS and RGO were prepared and tested as counter electrodes in QDSSCs. The preliminary results obtained from CdS-QDSSCs employing CuS-RGO CE demonstrate that high dependency on the content of the CuS nanoparticles into the counter …