Electron-assisted deposition and interface control of naphthalenediimide derivative thin films

Abstract

Stable film formation and interface control of electron-transporting polymers are important key issues for developing organic devices. In this report, thin films of N,N'-bis(p-vinylbenzyl)naphthalenediimide (PVB-NDI) were prepared by the vapor deposition and an electron-assisted (e-assist) deposition methods on aluminum substrates. The aluminum surface was modified with self-assembled monolayers (SAMs) of (3-mercaptoprppyl) trimethoxysilane (MPTMS) or vinyltriethoxysilane for controlling the film/substrate interface. It was observed that the e-assist deposition can polymerize PVB-NDI in the process of film deposition. The polymerization was induced by the e-assist process, and was not influenced by the surface modification with the SAMs. It was found that the electron injection barrier height can be substantially decreased when the PVB-NDI film was prepared by the e-assist deposition on the aluminum surface modified with the SAM of MPTMS. This result implies that covalent tethering via the thiol-en reaction at the interface contributes to controlling the metal/organic interface.