Resident holes and electrons at organic/conductor and organic/organic interfaces: An electron paramagnetic resonance investigation

• Interface dipole.
• Integer Charge Transfer.
• HAT-CN.
• C60.
• EPR.

A number of organic/conductor and organic/organic interfaces have been examined by EPR spectroscopy to ascertain the areal concentration of organic ions at the interface. Organic hole transport materials such as NPB and TAPC at an interface with MoOx are found to have areal concentrations on the order of 1014 cations per cm2. C60 at an interface with MoOx creates ≈1013 cations per cm2 depending on the roughness of the substrate. However, C60 at an interface with Mg or Ag produces only about 4 × 1012 anions per cm2. Ion concentrations are generally in accord with the energy levels (adiabatic IP, EA etc) of the two materials at a given interface.

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