Charge Transfer at the Interface Between MnPc and F₆TCNNQ

Abstract

Photoelectron spectroscopy in the core level as well as the valence band region has been used to determine the electronic properties of interfaces between manganese phthalocyanine (MnPc) and the strong electron acceptor F 6 TCNNQ. It is shown that charge transfer occurs at this interface which results in the oxidation (reduction) of MnPc (F 6 TCNNQ) at the interface. Our data indicate a full electron transfer with no evidence for hybrid states. The valence band data suggest that the interface remains insulating/semiconducting despite the charge transfer, which indicates localized charges.

Charge transfer characteristics of F6TCNNQ–gold interface

“…For smaller coverages, a second species at 397.8 eV arises due to a larger contribution of the F 6 TCNNQ anion spectrum to the overall signal until for ML coverage only charged molecules are detected. A full ionization charge transfer can be considered for this substrate, which is also reported for F 4 TCNQ on gold 4 or F 6 TCNNQ on an organic donor film 8,17 . For a thickness of 0.7 nm, a fitted spectrum is plotted in Figure 3.…”

“…A full ionization charge transfer can be considered for this substrate, which is also reported for F 4 TCNQ on gold 4 or F 6 TCNNQ on an organic donor film. 8,17 For a thickness of 0.7 nm, a fitted spectrum is plotted in Figure 3. The 1.0 nm N1s spectrum cannot be fitted by two components only.…”

“…[1][2][3][4] The detailed knowledge about the energy level alignment or a possible charge transfer at these interfaces is crucial for the development of highly efficient applications. 5,6 Strong electron acceptor molecules such as tetraflouro-tetracyanoquinodimethane (F 4 TCNQ) or hexafluorotetracyanonaphthoquinodimethane (F 6 TCNNQ) are known for a strong interaction with various materials, for example, organic semiconductors, [7][8][9] anorganic semiconductors, 10,11 or even noble metals. 4,12 Mostly, an electron charge transfer from the host to the acceptor material and the formation of a localized interface dipole and an acceptor anion is observed, 8 especially between F 4 TCNQ and polycrystalline gold.…”

Controlling energy levels and Fermi level en route to fully tailored energetics in organic semiconductors

“…Previous experiments have shown that ground-state integer-charge transfer occurs for ZnPc:F-TCNNQ 8,12 , leading to at least partial polaron pair formation on the host H H and dopant D D. As the absorption coefficients of these sub-gap states are typically very low 17 , we perform photothermal deflection spectroscopy (PDS) measurements at room temperature.…”

“…However, as reported for the well-studied case of zinc-phthalocyanine (ZnPc) and molecular p-dopant F-TCNNQ 8–11 , this understanding of the doping mechanism is incomplete. Judging from the energy levels of the isolated molecules 1,12,13 , the doping process is expected to be more efficient than is experimentally observed 8 .…”