2.5. Solar Cell Fabrication and Investigation

Photovoltaic devices with ITO/PEDOT:PSS/SilPEG:PC61BM/Al structure were prepared by spin-coating of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) (M121, Ossila) films on ITO Glass Substrates (Ossila (Sheffield, UK) 6 pixels) at 5000 rpm for 40 s (30 nm). PEDOT:PSS films were annealed at 140 °C for 10 min. The solutions of SilPEG and PC₆₁BM (Solenne, 99.5% (Groningen, The Netherlands)) in chlorobenzene (Acros Organics, 99+ (Geel, Belgium)) solutions with 2:1 ratio and a total concentration of 25 mg/mL were filtered (Syringe Filters, 0.45 μm, PTFE membrane) at temperature of 60 °C directly before application. Active layers were spin-coated at 2000 rpm for 40 s on top of the PEDOT:PSS films, with a substrate temperature of 60 °C, and then dried at 130 °C for 10 min. Al electrodes (100 nm) were deposited on top of the active layers by thermal evaporation. The area of the device was 0.045 cm². IV-curves of photovoltaic devices were measured by a PV Test Solutions Solar Simulator and a Keithley 2400 (Tektronix, Inc., Beaverton, OR, USA) in a glove box without encapsulation of devices.