Ambipolar Transport in an Electrochemically Gated Single-Molecule Field-Effect Transistor
Author(s):
Ismael Díez-Pérez, Zhihai Li, Shaoyin Guo, Christopher Madden, Helin Huang, Yanke Che, Xiaomi Yang, Ling Zang, Nongjian Tao
Journal:
ACS Nano
Year:
2012
Volume:
6
Pages
7044-7052
DOI:
10.1021/nn302090t
Abstract:
Charge transport is studied in single-molecule junctions formed with a 1,7-pyrrolidinesubstituted 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) molecular block using an electrochemical gate. Compared to an unsubstituted-PTCDI block, spectroscopic and electrochemical measurements indicate a reduction in the highest occupied (HOMO)lowest unoccupied (LUMO) molecular orbital energy gap associated with the electron donor character of the substituents. The small HOMOLUMO energy gap allows for switching between electron- and hole-dominated charge transports as a function of gate voltage, thus demonstrating a single-molecule ambipolar field-effect transistor. Both the unsubstituted and substituted molecules display similar n-type behaviors, indicating that they share the same n-type conduction mechanism. However, the substituted-PTCDI block shows a peak in the sourcedrain current vs gate voltage characteristics for the p-type transport, which is
attributed to a two-step incoherent transport via the HOMO of the molecule.