Many recent experimental studies have demonstrated that the deposition of a self‐assembled monolayer (SAM) made of polar molecules on a metal surface can significantly modulate its work function and hence the barrier for hole and electron injection in optoelectronic devices. The permanent dipole moment associated with the backbone of the molecules plays a key role in defining the amplitude and direction of the work‐function shift. We illustrate here via quantum‐chemical calculations performed on model systems that the dipole moment of molecules is significantly reduced going from the isolated state to the SAM. Such depolarization effects that are most often neglected thus reduce the work‐function shift and have to be taken in account to control and understand charge‐injection barriers in devices at a quantitative level.

The electronic structure of the hybrid interface between ZnO and the prototypical organic semiconductor PTCDI is investigated via a combination of ultraviolet and X-ray photoelectron spectroscopy (UPS/XPS) and density functional theory (DFT) calculations. The interfacial electronic interactions lead to a large interface dipole due to substantial charge transfer from ZnO to 3,4,9,10-perylenetetracarboxylicdiimide (PTCDI), which can be properly described only when accounting for surface defects that confer ZnO its n-type properties.

STM brings to light chirality aspects of the self-assembly of a functionalized helicene at the interface between a liquid and the solid substrates, gold and graphite. This reveals conditions for conglomerate formation.

Tune it with light! Self-assembled monolayers on gold based on a chemisorbed novel azobenzene derivative with a perfluorinated terminal phenyl ring are prepared. The modified substrate shows a significant work function increase compared to the bare metal. The photo-conversion between trans and cis isomers chemisorbed on the surface shows great perspectives for being an accessible route to tune the gold properties by means of light.

Responsive monolayers are key building blocks for future applications in organic and molecular electronics in particular because they hold potential for tuning the physico-chemical properties of interfaces, including their energetics. Here we study a photochromic SAM based on a conjugated azobenzene derivative and its influence on the gold work function (Φ(Au)) when chemisorbed on its surface. In particular we show that the Φ(Au) can be modulated with external stimuli by controlling the azobenzene trans/cis isomerization process. This phenomenon is characterized experimentally by four different techniques, kelvin probe, kelvin probe force microscopy, electroabsorption spectroscopy and ultraviolet photoelectron spectroscopy. The use of different techniques implies exposing the SAM to different measurement conditions and different preparation methods, which, remarkably, do not alter the observed work function change (Φ(trans)-Φ(cis)). Theoretical calculations provided a complementary insight crucial to attain a deeper knowledge on the origin of the work function photo-modulation.