Efficiency enhancement of organic solar cell using surface plasmon resonance effects of Ag nanoparticles

摘要

Ag nanoparticles (NPs) of varied concentrations are implemented in the hole transport layer (PEDOT:PSS) of organic solar cells to enhance the photoconversion efficiency through near field effects, one of the basis of surface plasmonic resonances. The Ag NPs were synthesized through a wet chemistry reduction process by varying the reaction times to yield different sizes and shapes of Ag NPs, with diameters/effective sizes in the range 20-30 nm. The morphology, shape and size of the Ag NPs are examined by Transmission Electron Microscopy (TEM). Selected Area Electron Diffraction has confirmed that the dispersed and regularly shaped Ag NPs are polycrystalline with an underlying face centered cubic structure. The dependence of the plasmonic resonances on the shape (size) of the nanoparticles is exhibited by broad optical absorption in the 350-550 nm spectral range. Efficient device performance is ascribed to PEDOT:PSS layers incorporated with 2% Ag NPs reporting a Photoconversion efficient of 3%. The addition of Ag NP creates strong localized fields, and we investigate their effects on the carrier mobility in the trap free space charge limited region through the corresponding Langevin recombination constants. Our results show an increase in barrier height associated with NPs addition as supported by the varying values of the ideality factors and series resistances.