Improving P3HT:PCBM based polymer solar cell: Role of doped PEDOT:PSS hole extracting layer towards degradation

Abstract

Films of PEDOT:PSS and doped PEDOT:PSS, used as hole extracting layer in organic solar cells, have been studied using scanning electron microscopy, Kelvin probe work function measurement, Col-Cole plots, and conductivity measurements and current voltage (I-V) characteristics with time. A change in morphology is observed in PEDOT:PSS films doped with ethylene glycol and multi-walled carbon nanotubes. The doped films have rougher morphology as compared to the pristine films. The work function increases for doped sample thus improving the charge transfer. Further, the analyses of Cole-Cole plots show that the resistance of doped film is lower than pristine film. The change in conductivity with time has been measured, and the I-V characteristics of fresh and degraded samples indicates that fall in conductivity of HEL is one of the reasons for the decrease in device performance.