Improved hole injection/extraction using PEDOT:PSS interlayer coated onto high temperature annealed ITO electrode for efficient device performances

Abstract

We demonstrate the improved device performances by using the structure of poly (3,4ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) lm coated onto the indium tin oxide (ITO) anodic electrode annealed at 400 °C under the normal ambient. The ITO thin lms show the improved lm quality with decreased dislocation density and lattice strain as annealing temperature increases. The spincoated PEDOT:PSS lm smoothens the wrinkle kind of surface morphology of the ITO lm annealed at 400 °C. The annealed ITO (400 °C) with PEDOT:PSS interlayer improves the hole-current density in the hole-only devices (HODs) having the device structure of ITO/PEDOT:PSS/N,N'-Bis(3-methylphenyl)-N,N'diphenylbenzidine as hole-transporting layer/Al. It enhances the e ciency of organic photovoltaic devices [ITO (annealed) /PEDOT:PSS/P3HT:PCBM (active layer)/LiF/Al] by three times higher (1.69 %) when compared to that (0.48 %) of pristine ITO based OPV device. These results show that the annealing of ITO lm at the high temperature of 400 °C under the normal ambient improves the lm quality and lowers the potential energy barrier at ITO/PEDOT:PSS interface for effective hole injection/extraction process, resulting in the enhanced device electrical performances.