We investigate the interaction between
a Fe(II) spin-crossover
molecule and a two-dimensional (2D) substrate. Using density functional
theory combined with molecular dynamics simulations, we explore the
configuration space and spin state energetics of the [Fe(py)2bpym(NCS)2] molecule adsorbed on the 2D semiconductor
MoS2. We show that the deposited molecule can display a
high-spin ground state, in contrast to the locking of a low-spin state
observed on metallic substrates. The variation can be primarily attributed
to the noncovalent interactions occurring at the interface. Furthermore,
the molecular doping of the n-type is examined from an electronic
structure point of view. Specifically, our calculations reveal a notable
shift of the band edge that can reach 0.3 eV due to fluctuations in
the electric dipole at the interface upon spin-state switching. This
observation indicates the possibility of regulating the photocatalytic
selectivity of hydrogen evolution and CO2 reduction reactions
within the heterostructure by manipulating the molecular spin state
using an external trigger.