Electronic properties and structure of single crystal perylene.

The transport properties of electronic devices made from single crystalline molecular semiconductors typically outperform those composed of thin-films of the same material. To further understand the superiority of these extrinsic device properties, an understanding of the intrinsic electronic structure and properties of the organic semiconductor is necessary. An investigation of the electronic structure and properties of single crystal α-phase perylene (CH), a five-ringed aromatic molecule, is presented using angle-resolved ultraviolet photoemission, x-ray photoelectron spectroscopy (XPS), and field-effect transistor measurements.

Non-fullerene acceptors: exciton dissociation with PTCDA versus C60.

Extensive development of new polymer and small molecule donors has helped produce a steady increase in the efficiency of organic photovoltaic (OPV) devices. However, OPV technology would also benefit from the introduction of non-fullerene acceptors. Unfortunately, efforts to replace fullerenes have typically led to significantly reduced efficiencies.

TiOPc molecular dislocation networks as nanotemplates for C60 cluster arrays.

By controlled deposition, TiOPc, a molecular semiconductor with anisotropic interactions can generate a molecular film with a characteristic pattern repeat size of 15 nm. This structure then served as a nanotemplate for a superlattice of C(60) clusters with characteristic diameters of 7 nm. As a result, C(60) deposition on the TiOPc film template forms a pattern of nanophase-separated C(60) and TiOPc domains with a characteristic domain size of 7 nm.

Fermi level alignment in self-assembled molecular layers: the effect of coupling chemistry.

Photoelectron spectroscopy was used to explore changes in Fermi level alignment, within the pi-pi* gap, arising from modifications to the coupling chemistry of conjugated phenylene ethynylene oligomers to the Au surface. Self-assembled monolayers were formed employing either thiol (4,4'-ethynylphenyl-1-benzenethiol or OPE-T) or isocyanide (4,4'-ethynylphenyl-1-benzeneisocyanide or OPE-NC) coupling. The electronic density of states in the valence region of the two systems are nearly identical with the exception of a shift to higher binding energy by about 0.

Valence electron orbitals of an oligo(p-phenylene-ethynylene)thiol on gold.

This communication reports measurement of one-photon (21.2 eV) and one-color, two-photon (3.2-4.