Charge Transport and Photovoltaic Properties of Conjugated Polymer PTB7:PC71BM Based Solar Cells

We investigate the charge transport in organic solar cells based on PTB7:PC71BM by measuring the J (V) characteristics at different temperatures (140–325 K). In dark, two models dominate the transport. The Ohmic law overcomes for the low applied low voltages, and for high voltages the trapped charge limited current governs the transport with an average total concentration of trap around 5.62 × 1015 cm−3. At higher voltages there is evidence of an electrode-to-bulk limited transition, with conductivity dominated by the Poole–Frenkel effect. The photovoltaic conversion properties of the junction were also studied by carrying out the J–V measurements at room temperature under illumination of 100 mW/cm2 and a power conversion efficiency of 6.49% has been achieved. the other cell parameters, the short-circuit current density JSC, the open circuit voltage VOC and de fill factor FF, were found to be 12.87 mA/cm2, 0.77 V and 0.65 respectively. These values were compared with other organic solar cells found in literature.