Study on the series resistance of crystal violet dye-based organic photovoltaic device in presence of single walled carbon nanotubes

The series resistance (Rs) of any organic photovoltaic device (OPV) plays an important role on the device performance. Generally, the electrode and the presence of traps at the interface contribute the high Rs. In this present work, we have studied the Rs of crystal violet dye-based OPV device and its variation in the presence of single walled carbon nanotubes (SWCNT). From the dark current voltage (I–V) characteristics, we have extracted Rs by using the Cheung–Cheung method. It is observed that the trap energy (Ec) and the value of Rs are decreased in the presence of SWCNT. The values of Rs and Ec are about 0.246 MΩ and 0.085 eV in the absence of SWCNT and these values change to 0.124 MΩ and 0.060 eV, respectively, in the presence of SWCNT. The light I–V characteristics of the devices have also been studied to find out the Rs of the device under illumination. Under illumination, the charge transport process is governed by the incident photon energy (Em) which is absorbed by the OPV device. So we have extracted the Em from the light I–V characteristics and estimated the Rs by using area method under light illumination in the absence and presence of SWCNT. It is observed that the extracted values of Rs under illumination are low compared to the values of Rs measured from dark I-V characteristics.