3 research outputs found
Adsorbate-induced curvature and stiffening of graphene
The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon−carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology
Size and Energy Level Tuning of Quantum Dot Solids via a Hybrid Ligand Complex
The performance of quantum dots (QDs)
in optoelectronic devices
suffers as a result of sub-bandgap states induced by the large fraction
of atoms on the surface of QDs. Recent progress in passivating these
surface states with thiol ligands and halide ions has led to competitive
efficiencies. Here, we apply a hybrid ligand mixture to passivate
PbSe QD sub-bandgap tail states via a low-temperature, solid-state
ligand exchange. We show that this ligand mixture allows tuning of
the energy levels and the physical QD size in the solid state during
film formation. We hereby present a novel, postsynthetic path to tune
the properties of QD films