  We study a model for photovoltaic energy collection consisting of a Mott
insulating layer in presence of acoustic phonons, coupled to two wide-band
fermion leads at different chemical potentials and driven into a nonequilibrium
steady state by a periodic electric field. We treat electron correlations with
nonequilibrium dynamical mean-field theory (DMFT) using the so-called auxiliary
master equation approach as impurity solver and include dissipation by acoustic
phonons via the Migdal approximation. For a small hybridization to the leads,
we obtain a peak in the photocurrent as a function of the driving frequency
which can be associated with impact ionization processes. For larger
hybridizations the shallow peak suggests a suppression of impact ionization
with respect to direct photovoltaic excitations. Acoustic phonons slightly
enhance the photocurrent for small driving frequencies and suppress it at
frequencies around the main peak at all considered hybridization strengths.
