  Van der Waals heterostructures based on TMDC semiconducting materials have
emerged as promising materials due to their spin-valley properties efficiently
contrived by the stacking-twist angle. The twist angle drastically alters the
interlayer excitonic response by determining the spatial modulation, confining
moir\'e potential, and atomic reconstruction in those systems. Nonetheless, the
impact of the interlayer twist angle on the band alignment of the monolayers
composing the heterostructure has received scant attention in the current
research. Here, we systematically investigate the twist-angle dependence of
intra- and inter-layer excitons in twisted WSe2/MoSe2 heterobilayers. By
performing photoluminescence excitation spectroscopy, we identify the
twist-angle dependence of interlayer emission response, where an energy
redshift of about 100 meV was observed for increasing twist angles. The applied
microscopic theory predicts, on the contrary, a blueshift, which suggests that
additional features, such as atomic reconstruction, may also surpass the
moir\'e potential confinement. Those findings also prompt the effects of
dielectric screening by addressing the redshift response to the stacking layer
order. Furthermore, our findings support the evidence of a band offset
dependence on the twist angle for the adjacent monolayers composing the
heterobilayer system. Our fundamental study of exciton resonances deepens the
current understanding of the physics of twisted TMDC heterostructures and paves
the way for future experiments and theoretical works.
