  Employing a large-N scheme of the layered t-J model with the long-range
Coulomb interaction, which captures fine details of the charge excitation
spectra recently observed in cuprate superconductors, we explore the role of
the charge fluctuations on the electron self-energy. We fix temperature at zero
and focus on quantum charge fluctuations. We find a pronounced asymmetry of the
imaginary part of the self-energy Im$\Sigma({\bf k}, \omega)$ with respect to
$\omega = 0$, which is driven by strong electron correlation effects. The
quasiparticle weight is reduced dramatically, which occurs almost isotropically
along the Fermi surface. Concomitantly an incoherent band and a sharp side band
are newly generated and acquire sizable spectral weight. All these features are
driven by usual on-site charge fluctuations, which are realized in a rather
high-energy region and yield plasmon excitations. On the other hand, the
low-energy region with the scale of the superexchange interaction J is
dominated by bond-charge fluctuations. Surprisingly, compared with the effect
of the on-site charge fluctuations, their effect on the electron self-energy is
much weaker even if the system approaches close to bond-charge instabilities.
Furthermore, quantum charge dynamics does not produce a clear kink nor a
pseudogap in the electron dispersion.
