  Combining the synthetic tunability of molecular compounds with the optical
selection rules of transition metal dichalcogenides (TMDC) that derive from
spin-valley coupling could provide interesting opportunities for the readout of
quantum information. However, little is known about the electronic and spin
interactions at such interfaces and the influence on spin-valley relaxation. In
this work we investigate various heterojunctions of vanadyl phthalocyanine
(VOPc) thermally evaporated on WSe$_2$ and find that local ordering of the
molecular layer plays an important role in the electronic perturbation of
WSe$_2$, which in turn directly influences the spin-valley polarization
lifetime. A thin molecular layer results in a hybrid state which destroys the
spin-valley polarization almost instantaneously, whereas a thicker molecular
layer with well-defined local ordering shows minimal electronic perturbation
and results in longer-lived spin-valley polarization than the WSe$_2$ monolayer
alone.
