Highly efficient top-emitting organic light-emitting diodes with self-assembed monolayer-modified Ag as anodes

Abstract

A series of p-substituted benzylmercaptans was used to form self-assembled monolayers (SAMs) on silver surface to serve as the anode in the fabrication of top-emitting organic light-emitting diodes. SAMs with electron-withdrawing substituents such as cyano and trifluoromethyl groups led to enhanced hole injection and electroluminescent performance, whereas the opposite is true for electron-donating groups. Direct quantitative correlation between the molecular dipole moment/work function or work function/hole injection does not exist. A high current efficiency of ∼12cd∕A was obtained, which is two and half times that of the conventional bottom-emitting device of the same layer structure.