4th International congress on Engineering,Architecture and Design,2019, İstanbul, Turkey, 23 - 24 April 2019, pp.116-124
Graphene nanosheets have been prepared from fine graphite powders by a novel electrochemical exfoliation method. In order to electrochemically exfoliate graphene, powders were first pressed into a bulk pellet shape. This pellet was then exfoliated on stainless steel (1810 CrNi) wire cage in 0.1 M aqueous sodium sulfate (Na2SO4) electrolyte solution in an ultrasonic cleaning bath with mild sonication (45 W). Pt wires have been used as anode and cathode with a bias voltage of 10 V to facilitate the process. After the process, the electrolyte solution was then washed copiously with DI water and filtered via vacuum filtration using 0.2 µm pore sized PTFE filter to remove residual salts. As filtered product dried in an oven at 80 oC overnight to remove water. Synthesized graphenes have been characterized by FE-SEM, Raman, and FT-IR spectroscopy. Graphenes were dispersed in N,N-Dimethylformamid (DMF) via mild sonication and centrifuged at 4000 rpm to remove non-exfoliated large particles. Obtained supernatant shows a stable suspension. This suspension then used in organic solar cells (OSCs) as an additive to PEDOT:PSS to be utilized as a hole transport layer (HTL). Organic solar cells have been prepared in ITO/PEDOT:PSS-Graphene/P3HT:PCBM/Al formation using spin coating and vacuum thermal evaporation techniques. Reference devices with only PEDOT:PSS and PEDOT:PSS-DMF have also been prepared. The photovoltaic cell with prepared with graphene exhibited superior efficiency compared to PEDOT:PSS (%63) and PEDOT:PSS-DMF (%14) respectively.