Charge carrier transport in poly(p-phenylene vinylene):methanofullerene photovoltaic blends

The charge carrier transport and energetic disorder in OC1C10-PPV:PCBM blends with different fullerene concentrations are investigated. We demonstrate that the temperature-dependent current density versus voltage (J-V) characteristics of PCBM electron-only device and OC1C10-PPV hole-only device can be accurately described using our recently introduced improved mobility model. Furthermore, the J-V characteristics of OC1C10-PPV: PCBM blends that were measured in electron-only and hole-only devices for different wt% of PCBM can also be accurately described by the improved mobility model. Additionally, we find that the width of the Gaussian density of states sigma and zero-field mobility of electron and hole in OC1C10-PPV:PCBM blends are the function of wt% PCBM. For electron-only devices based on OC1C10-PPV:PCBM blends, the electron mobility gradually increases with increase in the PCBM weight ratio, while the width of the Gaussian density of states sigma gradually decreases with increase in the PCBM weight ratio. Surprisingly, the hole mobility and the width of the Gaussian density of states sigma in hole-only devices based on OC1C10-PPV:PCBM blends show an identical behavior. These results provide information about the energetic disorder and a simplified modeling of the charge transport in disordered organic semiconductors.