  Twist angle modifies the band alignment, screening, and interlayer (IL)
coupling in twisted bilayers (tBLs) of transition metal dichalcogenides.
Intermediate misorientation (twist angles > 15 degrees) bilayers (BLs) offer a
unique opportunity to tune excitonic behavior within these concurrent physical
mechanisms but are seldom studied. In this paper, we measure many-body
excitonic complexes in monolayer (ML), natural BL, and tBL WSe2. Neutral
biexciton (XX) is observed in tBL, while being undetected in nonencapsulated ML
and BL, demonstrating unique effects of disorder screening in tBLs. The XX as
well as charged biexciton are robust to thermal dissociation and are
controllable by electrostatic doping. Vanishing of momentum-indirect IL
excitons with increasing electron doping is demonstrated in tBL, resulting from
the near alignment of Q-K and K-K valleys. Intermediate misorientation samples
offer a high degree of control of excitonic complexes while offering
possibilities for studying exciton-phonon coupling, band alignment, and
screening.
