Abstract

• For the fabrication of MEH-PPV:PCBM solar cells, the bulk heterojunction blend solutions of MEH-PPV:PCBM (1:2 wt%) were prepared in chloroform, dichlorobenzene, toluene and xylene. A thin layer of poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) or (PEDOT:PSS) was spin-coated on pre-cleaned ITO glass plates. Then the PEDOT: PSS coated substrate was annealed at 100ºC for 15 min. Subsequently, MEH-PPV:PCBM photoactive layer was spun-coat at 1000 rpm for 60 s on the top of PEDOT:PSS layer. After annealing at 130°C for 8 min, the devices were completed by deposition of cathode aluminum through a mask by thermal evaporation at a pressure of 10-6 Torr. The I-V curves of the devices were recorded under illumination of light intensity (100 mWcm-2 ). The photovoltaic efficiency of organic solar cells were evaluated from the J-V characteristics of the device. It was measured using a computer-controlled digital source meter (Keithley 2420) with a Newport solar simulator (A.M. 1.5, 100 mWcm-2 ). Light intensity was calibrated with a National Renewable Laboratory (NREL)-calibrated monocrystalline Silicon solar cell.