Suppression of trap assisted non-geminate recombination by incorporation of multilayer graphene in P3HT:PCBM for stable and efficient photovoltaic device

In the present work, multilayer graphene (MLG) has been demonstrated to be a promising material for improvement in power conversion efficiency (PCE) as well as stability of the polymer based photovoltaic (PV) devices. MLG, when incorporated into the active layer of the P3HT:PCBM based PV device provides additional 2D pathways for long distance electron transport, avoiding interaction with holes and hence leading to suppression of non-geminate recombination in the device. PCE of the device is shown to improve by similar to 54% due to improvement in absorbance as well as by reduction in non-geminate recombination leading to similar to 8.9% increase in short circuit current density. Also, open circuit voltage improves by similar to 13.75% owing to increase in the fermi-level splitting due to large number of charge accumulated at the electrodes. MLG also reduces the rate of degradation of the device by the factor of similar to 1.5 by suppressing the effect of generation of deep trap levels in the active layer which in turn results in improving the stability of the device.