  MoSe2-WSe2 heterostructures host strongly bound interlayer excitons (IXs)
which exhibit bright photoluminescence (PL) when the twist-angle is near
0{\deg} or 60{\deg}. Over the past several years, there have been numerous
reports on the optical response of these heterostructures but no unifying model
to understand the dynamics of IXs and their temperature dependence. In this
letter, we perform a comprehensive study of the temperature, excitation power,
and time-dependent PL of IXs. We observe a significant decrease in PL intensity
above a critical temperature that we attribute to a transition from localized
to delocalized IXs. We conclude that this temperature dependence is a result of
IX-IX interactions, which is suppressed by the moir\'e potential trapping IXs
at low temperature. Astoundingly, we find a simple inverse relationship between
the IX PL energy and the critical temperature, which exhibits opposite power
dependent behaviors for near 0{\deg} and 60{\deg} samples.
