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Effects of Molecular Orientation in Acceptor–Donor Interfaces between Pentacene and C 60 and Diels–Alder Adduct Formation at the Molecular Interface
Author(s) -
Breuer Tobias,
Karthäuser Andrea,
Witte Gregor
Publication year - 2016
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201500452
Subject(s) - pentacene , materials science , chemical physics , acceptor , molecule , xanes , fullerene , crystallography , layer (electronics) , nanotechnology , spectroscopy , organic chemistry , chemistry , condensed matter physics , thin film transistor , physics , quantum mechanics
Interfaces between pentacene and Buckminster‐fullerene (C 60 ) have attracted interest due to their application as oligomeric model system for organic solar cells. As the actual device characteristics in such implementations are crucially controlled by the interface structure, detailed investigations of this interface on a molecular level are mandatory. In this study, the influence of the orientation of the pentacene molecules in highly ordered crystalline bottom layers on the characteristics of such internal interfaces is analyzed. It has been shown that the interface structure is driven by temperature‐controlled diffusion of C 60 molecules to the pentacene step edges in the case of uprightly oriented pentacene. For lying pentacene in the bottom layer, no step‐edge decoration is observed while the wetting of the pentacene layer is enhanced. Furthermore, the stability of the interface against intercalation and reorientation has been analyzed by means of NEXAFS spectroscopy, showing that the orientation of the pentacene molecules at the interface remains unchanged. Instead, strong indication for chemical modification of the molecular entities by the formation of Diels–Alder adducts between C 60 and pentacene is observed. Finally, it is shown that C 60 forms crystalline islands in thicker films only on top of uprightly oriented pentacene while rather amorphous films are formed on lying pentacene.