  Layered chalcogenide materials have a wealth of nanoelectronics applications
like resistive switching and energy-harvesting such as photocatalyst owing to
rich electronic, orbital, and lattice excitations. In this work, we explore
monochalcogenide germanium selenide GeSe with respect to substitutional doping
with 13 metallic cations by using first-principles calculations. Typical
dopants including s-shell (alkali elements Li and Na), p-shell (Al, Pb and Bi),
3d (Fe, Cu, Co and Ni), 4d (Pd and Ag) and 5d (Au and Pt) elements are
systematically examined. Amongst all the cationic dopants, Al with the highest
oxidation states, implying a high mobility driven by electric field, and
Al-doped GeSe may be a promising candidate for novel resistive switching
devices. We show that there exist many localized induced states in the band gap
of GeSe upon doping Fe, Co, or Ni, while for Cu, Ag, and Au cases there is no
such states in the gap. The Ag and Cu are + 0.27 and + 0.35 charged
respectively and the positive charges are beneficial for field-driven motion in
GeSe. In contrast, Au is slightly negatively charged renders Au-doped GeSe a
promising photocatalyst and enhanced surface plasmon. Moreover, we explore the
coexistence of dopant and strain in GeSe and find dynamical adjustments of
localized states in GeSe with levels successive shifting upward/downward with
strain. This induces dynamic oxidative states of the dopants under strain which
should be quite popular in composites where motion of metal adatoms causes
significant deformation.
