In this study,we investigate the influence of doping on the charge transfer and device characteristics parameters in the bulk heterojunction solar cells based on poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM).Organic semiconductors are also known to be not pure and they have defects and impurities,some of them are being charged and act as p-type or n-type dopants.Calculations of the solar cell characteristics parameters versus the p-doping level have been done at three different n-dopings (Nd) that consist of 5 × 1017 cm-3,1018 cm-3,and 5 × 1018 cm-3.We perform the analysis of the doping concentration through the drift-diffusion model,and calculate the current and voltage doping dependency.We find that at three different n-dopant levels,optimum p-type doping is about Np =6 × 1018 cm-3.Simulation results have shown that by increasing doping level,Voc monotonically increases by doping.Cell efficiency reaches its maximum at somewhat higher doping as FF has its peak at Np =3 × 1018 cm-3.Moreover,this paper demonstrates that the optimum value for the p-doping is about Np =6 × 1018 cm-3 and optimum value for n-dopant is Nd =1018 cm-3,respectively.The simulated results confirm that doping considerably affects the performance of organic solar cells.
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