Vacuum-Level Shift at Al/LiF/Alq(3) Interfaces: A First-Principles Study

[Image: see text] Work function changes, or vacuum-level shifts (Δ(VLS)), in Al(001) surfaces by the adsorption of thin layers composed of tris(8-hydroxyquinolinato)aluminum (Alq(3)) and/or LiF are theoretically investigated. First-principles calculations reasonably reproduce experimentally obtained Δ(VLS) values, enabling us to discuss the underlying mechanism. Dipole moment of Alq(3) and interfacial charge rearrangement (Pauli push-back effect) are the main reasons for Δ(VLS) at Al(001)–Alq(3) and Al(001)–LiF interfaces, respectively. For a stacked Al(001)–LiF–Alq(3) layer configuration, theory suggests a more complicated picture, which takes charge rearrangement between LiF and Alq(3) layers into account, than a simple sum rule of dipole contributions from the two layers.