From a bistable adsorbate to a switchable interface: tetrachloropyrazine on Pt(111)

TL;DR

This study demonstrates a reversible switchable interface using tetrachloropyrazine on Pt(111), enabling dynamic control of surface properties relevant for organic electronic devices through structural changes.

Contribution

It introduces a novel reversible switching mechanism at organic/inorganic interfaces using a combined computational and experimental approach.

Findings

Identification of multiple switchable interface structures

Demonstration of reversible switching via temperature and pressure

Different work function and coherent fraction states achieved

Abstract

Virtually all organic (opto)electronic devices rely on organic/inorganic interfaces with specific properties. These properties are, in turn, inextricably linked to the interface structure. Therefore, a change in structure can introduce a shift in function. If this change is reversible, it would allow constructing a switchable interface. We accomplish this with tetrachloropyrazine on Pt(111), which exhibits a double-well potential with a chemisorbed and a physisorbed minimum. These minima have significantly different adsorption geometries allowing the formation of switchable interface structures. Importantly, these structures facilitate different work function changes and coherent fractions (X-ray standing wave measurements), which are ideal properties to readout the interface state. We perform surface structure search using a modified version of the SAMPLE approach and account for thermodynamic conditions using ab-initio thermodynamics. This allows investigating millions of commensurate as well as higher-order commensurate interface structures. We identify three different classes of structures exhibiting different work function changes and coherent fractions. Using temperature and pressure as handles we demonstrate the possibility of reversible switching between those different classes, creating a dynamic interface for potential applications in organic electronics.