Singlet Exciton Diffusion in Vacuum‐Evaporated Films of Amine‐Based Materials as Studied by Photocurrent and Photoluminescence Quenching Methods

Abstract

The singlet exciton diffusion lengths are determined by the photoconductivity as well as the luminescence surface quenching technique, in vacuum‐evaporated layers of (4,4′,4″‐tris(N‐(3‐methylphenyl)‐N‐phenylylamino) triphenylamine) (m‐MTDATA), 4,4′,4″‐tris[2‐naphthyl(phenyl)amino] triphenylamine (2TNATA), and N,N′‐diphenyl‐N,N′‐bis(3‐methylphenyl)‐[1,1′‐biphenyl]‐4,4′‐diamine (TPD) which are frequently used for fabrication of electroluminescent and photovoltaic devices. The values are found to be as high as (30 ± 10) nm in 2TNATA and m‐MTDATA, as well as (46 ± 9) nm in TPD films. The corresponding singlet diffusion coefficients of the range between 1 × 10−3 and 1 × 10−2 cm2 s−1, according to a comprehensive study undertaken, are assigned to a sizable electronic coupling induced by strong interactions of intra‐ and inter‐molecular origin in the investigated materials.