Impact of Surface Defects on the Charge Transfer at Inorganic/Organic Interfaces

Present models for the level alignment at inorganic/organic interfaces mostly consider ideal metallic or insulating substrates, neglecting surface defects. In this work, we use hybrid density functional theory to determine the impact of such defects on the interfacial charge transfer, using the adsorption of tetrafluoro-1,4-benzoquinone on Cu and defect-free as well as defective Cu2O as an example. The defects act as reaction centers and qualitatively change the way substrate and adsorbate interact, resulting in notable charge transfer where idealized models would predict none. Focusing on the impact of this defect-mediated charge transfer on several relevant observables, we discuss how it would affect the experimental studies of (defective) inorganic/organic interfaces.