The largest transfer integral for charge propagation in pentacene close to the interface with the gate insulator as a function of the relative static permittivity of the dielectric. The charge carrier is located on the first monolayer close to the interface. The high-frequency dielectric constant for the gate insulators is 2.65 for parylene C, 2.37 for , 3.1 for , 4.12 for , and 6.5 for .
The image potential at the interface is given in the continuous approximation and in our lattice model. At large distances from the interface the electronic polarization energy in the bulk is recovered.
(Color online) These are the same results as in Fig. 1 but calculated with another set of data as explained in Appendix B. The largest transfer integral for charge propagation in pentacene close to the interface with the gate insulator is plotted as a function of the relative static permittivity of the dielectric. The charge carrier is assumed to be located on the first monolayer. The inset depicts the case where the charge carrier is on the second monolayer. These curves cumulate all the effects calculated in this work. In contrast to the results of Fig. 1 we have assumed here that the carrier distribution is pulled away or squeezed towards the interface according to the calculation in Appendix B. This effect is enhanced with respect to the semiempirical model of Ref. 14. Here the effective mass depends even on the gate field. At present, the corresponding values calculated in Fig. 1 are considered more reliable.
Reduction factors of the transfer integral due to electronic polarization, intramolecular phonons, and Fröhlich surface polaron. Cases of bulk pentacene and interfaces with vacuum and different dielectric oxides are shown along with the time scales characterizing each process. Here the effect related to charge displacement on the molecule was excluded.
Crystal constants of pentacene (Ref. 24).
Values of the surface phonon frequencies used in the calculations of Appendix D together with the coupling constant .
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