  Photon impingement is capable of liberating electrons in electronic devices
and driving the electron flux from the lower chemical potential to higher
chemical potential. Previous studies hinted that the thermodynamic efficiency
of a nano-sized photoelectric converter at maximum power is bounded by the
Curzon-Ahlborn efficiency. In this study, we apply quantum effects to design a
photoelectric converter based on a three-level quantum dot (QD) interacting
with fermionic baths and photons. We show that, by adopting a pair of suitable
degenerate states, quantum coherences induced by the couplings of quantum dots
(QDs) to sunlight and fermion baths can coexist steadily in nano-electronic
systems. Our analysis indicates that the efficiency at maximum power is no more
limited to Curzon-Ahlborn efficiency through manipulation of carefully
controlled quantum coherences.
