Jump to main content
Jump to site search


Image-force effects on energy level alignment at electron transport material/cathode interfaces

Author affiliations

Abstract

Electron transport materials (ETMs) are widely used as interlayers to lower the cathode electrode work function in organic solar cells and organic light-emitting diodes, for example. The usual interpretation for their operating principle is a chemical interaction between the ETM and the electrode, inducing partial or integer charge transfer or collectively an intrinsic dipole moment caused by preferential molecular orientation. Herein, we systematically explore the commonly used ETM bathophenanthroline (BPhen) deposited on a series of conducting substrates. The energetics at the BPhen interface follows the typical integer charge transfer (ICT) model with an extra displacement of the vacuum level by up to −1.4 eV. The extra displacement is ascribed to the “double dipole step” formed by the positive and negative charged species and their induced image charges when they are close to the surface of substrates. After n-type doping the displacement is further increased to −1.8 eV, yielding a larger work function modification than obtained using typical electrolytes and zwitterions as cathode interlayer.

Graphical abstract: Image-force effects on energy level alignment at electron transport material/cathode interfaces

Back to tab navigation

Supplementary files

Publication details

The article was received on 17 Sep 2019, accepted on 22 Nov 2019 and first published on 25 Nov 2019


Article type: Paper
DOI: 10.1039/C9TC05128G
J. Mater. Chem. C, 2020, Advance Article

  •   Request permissions

    Image-force effects on energy level alignment at electron transport material/cathode interfaces

    Y. Chen, X. Liu, S. Braun, Y. Wang and M. Fahlman, J. Mater. Chem. C, 2020, Advance Article , DOI: 10.1039/C9TC05128G

Search articles by author

Spotlight

Advertisements