Current Rectification in a Langmuir−Schaefer Monolayer of Fullerene-bis-[4-diphenylamino-4‘ ‘-(N-ethyl-N-2‘ ‘‘-ethyl)amino-1,4-diphenyl-1,3-butadiene] Malonate between Au Electrodes

Abstract

Langmuir-Schaefer (LS) monolayer films of fullerene-bis-[4-diphenylamino-4' '-(N-ethyl-N-2' ''-ethyl)amino-1,4-diphenyl-1,3-butadiene] malonate, 1, sandwiched between two Au electrodes, exhibit pronounced current asymmetries (rectification) between positive and negative bias at room temperature, with no decay of the rectification after several cycles. The device shows symmetrical through-space tunneling for a bias up to +/-3 V, and asymmetrical, unimolecular, "U" type rectifier behavior in the voltage range from +/-3.0 to +/-5.4 V, with rectification ratios up to 16.5. The rectification is ascribed to the asymmetric placement of the relevant molecular orbitals, with respect to the metallic electrodes.

Rectification in Supramolecular Zinc Porphyrin/Fulleropyrrolidine Dyads Self‐Organized on Gold(111)

“…see refs. [31,38]) is required. Due to the size of our system, such simulations are computationally too expensive; moreover, coupling to the substrate is expected to be very similar in ZnTPP and ZnTPP/PyC 2 C 60 .…”

Comparison between the Photophysical Properties of Pyrazolo‐ and Isoxazolo[60]fullerenes with Dual Donors (Ferrocene, Aniline and Alkoxyphenyl)

“…[21] Indeed a fullerene derivative with an electrochemical HOMO-LUMO gap, which is about 1 eV, was recently exploited as a molecular rectifier. [22] From the first E red of C 60 and the first E ox of the donor moieties, the free-energy changes (∆G CR ) of the radical ionpairs were calculated from the Weller equation [23] and are reported in Table 2. From ∆G CR and the excited energies (E 00 ) of C 60 , the free-energy changes of the charge-separation process (∆G CS ) via the singlet excited state of C 60 ( 1 C 60 *) were calculated.…”

A Molecular Diode with a Statistically Robust Rectification Ratio of Three Orders of Magnitude

“…31 For these diodes to work optimally, that is, high values of R, it is important to optimize both the electronic (especially the coupling of the Fc units to the electrodes) 28 and the supramolecular structure of the junctions (for example, the roughness of the electrode materials, 28 purity of the SAM precursor, 32 and the SAM packing 29 ). Thus, it is important to optimize every aspect of the junctions to maximize the values of R.Although molecular diodes based on a single donor moiety work well, molecular diodes based on two energetically accessible molecular energy levels are promising to yield high values of R. Molecular diodes with both donor (where the highest occupied molecular orbital (HOMO) is localized) and acceptor (where the lowest unoccupied molecular orbital (LUMO) is localized) moieties (symmetrically or asymmetrically positioned inside the junctions) have been studied before, 18,21,[23][24][25]27,33 but controlling the energy level alignment of both the HOMO and LUMO with respect to each other and to the Fermi-levels of both electrodes is challenging. 11,23,34 The question whether the two energy levels that participate in the mechanism of charge transport have to be a LUMO and…”