Optical, structural, and electrical properties of PEDOT:PSS thin films doped with silver nanoprisms

Abstract

Conductive thin films of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) are common buffer layers widely applied in organic solar cells. In order to explore the implications of the localized surface plasmon resonance of noble metal nanoparticles in such applications, we prepared a series of hybrid PEDOT:PSS thin films doped with different proportions of colloidal Ag nanoprisms. Various characterization techniques, including transmission electron microscopy, regular and conductive atomic force microscopy, optical absorption, goniophotometry, and four-point probe resistance measurements, were applied to study the effects of Ag nanoprisms on the optical, structural, and electrical properties of the hybrid films. Through analyzing the Bidirectional Reflectance Distribution Functions (BRDF) of different hybrid films, we compared among different hybrid films the proportions of light being scattered and absorbed over various reflected angles. In terms of optical properties, with higher Ag nanoprism concentration, increased light scattering was found in the hybrid films which can potentially improve the light harvest in organic solar cells. In terms of structural and electrical properties, the surface roughness and the global sheet resistance of hybrid films were found to increase as the concentration of Ag nanoprism increases. The magnitude of the sheet resistance in these hybrid films was reduced to a level comparable to or smaller than those observed in pristine PEDOT:PSS films by increasing the extent of post-synthesis nanoprism purification and by applying organic solvent additives.