Zero-Point Fluctuations in Naphthalene and Their Effect on Charge Transport Parameters

Abstract

We calculate the effect of vibronic coupling on the charge transport parameters in crystalline naphthalene, between 0 and 400 K. We find that nuclear fluctuations can cause large changes in both the energy of a charge on a molecule and on the electronic coupling between molecules. As a result, nuclear fluctuations cause wide distributions of both energies and couplings. We show that these distributions have a small temperature dependence and that, even at high temperatures, vibronic coupling is dominated by the effect of zero-point fluctuations. Because of the importance of zero-point fluctuations, we find that the distributions of energies and couplings have substantial width, even at 0 K. Furthermore, vibronic coupling with high energy modes may be significant, even though these modes are never thermally activated. Our results have implications for the temperature dependence of charge mobilities in organic semiconductors.

Interaction of charge carriers with lattice and molecular phonons in crystalline pentacene

“…[3][4][5][6][7][8][9][10] On this respect, two main limitations of our calculations have to be kept in mind, namely, the restriction to optical phonons, and the harmonic approximation. While the first limitation can be overcome, at least in an approximate way, 40 the second is far more difficult to deal with.…”

“…1,2 Several authors have pointed out that in addition to Holstein (local) electron-phonon coupling, also non-local (Peierls) coupling has to be introduced in consistent models of charge transport. [3][4][5][6][7][8][9][10] Testing of theories of course requires proper assessment of the relevant parameters, and in this respect computational methods have been the preferred approach. However, due to the approximations implicit in the calculations, it is important to use the same methodology for different systems, therefore assessing the relative values of the resulting parameters, and to have a step by step comparison with the experimental data.…”

Time-Dependent Theory of the Rate of Photo-induced Electron Transfer

“…In this case, the onset of a small conductance increase is only observed when the biased chemical potential between the two electrodes is larger than the junction’s vibrational quanta, leading to a discontinuity in the first derivative of the current–voltage ( I – V ) curve, better represented as a peak in the second derivative of an I – V graph . In fact, even at zero temperature, the ET is not completely suppressed thanks to the zero-point fluctuations …”

Influence of Structural Dynamics on Polarization Energies in Anthracene Single Crystals

“…The impact of the dynamical disorder on the electronic couplings (referred to as nonlocal or Peierls electron−vibration interaction) has been investigated by several groups who followed various computational strategies. − Recent studies on naphthalene single crystals have pointed to significant interactions with both inter- and intramolecular vibrations and have emphasized the role of zero-point fluctuations. , …”