Valence Band Dependent Charge Transport in Bulk Molecular Electronic Devices Incorporating Highly Conjugated Multi-[(Porphinato)Metal] Oligomers

Molecular electronics offers the potential to control device functions through the fundamental electronic properties of individual molecules, but realization of such possibilities is typically frustrated when such specialized molecules are integrated into a larger area device. Here we utilize highly conjugated (porphinato)metal-based oligomers (PMn structures) as molecular wire components of nanotransfer printed (nTP) molecular junctions; electrical characterization of these “bulk” nTP devices highlights device resistances that depend on PMn wire length. Device resistance measurements, determined as a function of PMn molecular length, were utilized to evaluate the magnitude of a phenomenological β corresponding to the resistance decay parameter across the barrier; these data show that the magnitude of this β value is modulated via porphyrin macrocycle central metal atom substitution [β(PZnn; 0.065 A–1) < β(PCun; 0.132 A–1) < β(PNin; 0.176 A–1)]. Cyclic voltammetric data, and ultraviolet photoelectron spec...