The appeal of molecular electronics lies in the easy bottom-up fabrication of nanostructures with functions that mimic, and sometimes surpass, those of traditional electronic components, while achieving ultimate spatial density. Over the past four decades, numerous molecular building blocks have been proposed to perform electronic functions that include quantised conduction, switching between conductance states, current amplification and rectification. For binary data storage at the molecular level, most results have been obtained in ultrahigh vacuum (UHV), often combined with low temperatures (liquid nitrogen or below). In many cases, switching has been demonstrated in principle but was not achieved at the single molecule level, or the switching units failed to form ordered layers. Over the past years, we have studied a number of molecular systems at solid–liquid and electrochemical interfaces that have increased our understanding of structure formation and the factors that govern switching between different structures [1–5]. Here, we report a molecular dipole that self-assembles into highly ordered patterns at the liquid–solid interface and that can be switched at room temperature between a bright and a dark state at the single molecule level, see figure [6]. Using a scanning tunnelling microscope (STM) under suitable bias conditions, we can write binary information at a density of up to 41 Tb/cm2 (256 Tb/in2). The written information is stable during reading at room temperature, but can also be erased instantly by proper choice of tunnelling conditions. DFT calculations indicate that the contrast and switching mechanism originate from the stacking sequence of the molecular dipole, which is reoriented by the electric field between tip and substrate.

Ambient bistable single dipole switching in a molecular monolayer

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.