Formation of MoO3/Organic Interfaces

Molybdenum trioxide (MoO3) has been extensively used in numerous organic semiconductor devices for hole injection and extraction. In this paper, photoelectron spectroscopy combined with cleavage and sputter depth profile has been used to probe the structures of buried MoO3/organic semiconductor interfaces. Organics used in this work include: tris(4-carbazoyl-9-ylphenyl)amine (TCTA), N,N '-bis(naphthalene-l-yl)-N,N '-bis(phenyl)benzidine (NPB), 4,4 '-bis(carbazol-9-yl)-2,2 '-biphenyl (CBP), and 1,3-bis(N-carbazolyl) benzene (mCP). It is found that there are two distinct types of interfaces: sharp interfaces (type-I) where the oxide layer has limited or no diffusion when deposited on organics that have a high glass transition temperature such as TCTA and NPB; mixed interfaces (type-II) where the formation of interfaces is followed by significant diffusion and reaction on organics having low glass transition temperatures such as CBP and mCP. The causes for these two types of interfaces are discussed.

Automated summary

In this study, two distinct types of interfaces formed between MoO3 and different organic semiconductors have been discovered: sharp interfaces (type-I) formed on organic semiconductors with high glass transition temperatures, and mixed interfaces (type-II) formed on organic semiconductors with low glass transition temperatures.