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Impact of Functionalized Polystyrenes as the Electron Injection Layer on Gold and Aluminum Surfaces: A Combined Theoretical and Experimental Study
Author(s) -
Papadopoulos Theodoros A.,
Li Hong,
Kim EungGun,
Liu Jie,
Cella James A.,
Heller Christian M.,
Shu Andrew,
Kahn Antoine,
Duggal Anil,
Brédas JeanLuc
Publication year - 2014
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.201400041
Subject(s) - work function , chemistry , bilayer , monolayer , polystyrene , polymer , surface modification , layer (electronics) , self assembled monolayer , cathode , x ray photoelectron spectroscopy , thin film , ultraviolet photoelectron spectroscopy , chemical engineering , analytical chemistry (journal) , nanotechnology , organic chemistry , materials science , computational chemistry , electronic structure , membrane , engineering , biochemistry
At metal/organic interfaces, the insertion of an organic monolayer can significantly modify the surface properties of the substrate, especially in terms of charge injection across the interface. Herein, we study the formation of an insulating monolayer of morpholine or amine‐functionalized polystyrene on Al(111) and Au(111) surfaces and its impact on surface work‐function and charge injection. First‐principles calculations based on Density Functional Theory have been carried out and point to a significant decrease in the work‐function of modified metal surfaces; this is in very good agreement with ultraviolet photoemission spectroscopy measurements performed on the Au(111) surface. In addition, a bilayer cathode, consisting of a thin film of high‐work‐function metal, such as Al and Au, and a layer of amine‐functionalized polystyrene, was also fabricated and tested in organic light‐emitting diodes. Such bilayer structures exhibit substantially enhanced efficiency when compared with controls without the functionalized polymers. Our combined theoretical and experimental investigation gives insight into how a thin layer of a commodity polymer can be used to transform rather high‐work‐function metals into high‐performance cathodes to provide efficient electron injection.