Twist angle modifies the band alignment, screening, and interlayer (IL) coupling in twisted bilayers (tBLs) of transition metal dichalcogenides. Intermediate misorientation (twist angles $>$ ${15}^{\circ }$) 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 ${\mathrm{WSe}}_2$. 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 ($X{X}^{-}$) 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 near alignment of $Q^{\prime }\text{−}K$ and $K\text{−}K$ valleys. Intermediate misorientation samples offer a high degree of control of excitonic complexes while offering possibilities of studying exciton-phonon coupling, band alignment, and screening.

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• Excitons
• Trions
• Twisted heterostructures
• First-principles calculations
• Photoluminescence