Mechanism of charge transport along zinc porphyrin-based molecular wires.
In this study charge transport along zinc porphyrin-based molecular wires is simulated, considering both bandlike and hopping mechanisms. It is shown that bandlike transport simulations yield significantly overestimated hole mobility values. On the basis of kinetic and thermodynamic considerations, it is inferred that charge transport along zinc porphyrin-based molecular wires occurs by small polaron hopping. Hole mobility values on the order of 0.1 cm(2) V(-1) s(-1) are found from small polaron hopping simulations, which agree well with previously reported experimental results. It is suggested that the experimentally observed increase of the charge carrier mobility on formation of supramolecular ladderlike structures is determined by two factors. One of these is an increase of charge transfer integrals between monomer units due to molecular wire planarization. A more important factor is the reduction of the amount of energetic disorder along the molecular wire and in its environment. General guidelines for determining the mechanism of charge transport along molecular wires are discussed.
Kocherzhenko
Aleksey A
AA
Opto-Electronic Materials, DelftChemTech, Delft University of Technology, Julianalaan 136, 2628BL Delft, The Netherlands.
Patwardhan
Sameer
S
Grozema
Ferdinand C
FC
Anderson
Harry L
HL
Siebbeles
Laurens D A
LD