Figure 2: Low temperature photoluminescence spectrum of WX2.
From: Dark trions and biexcitons in WS2 and WSe2 made bright by e-e scattering

Sketch of the low temperature (kBT < ΔSO) photoluminescence spectrum of WX2 including the bright exciton, dark and bright trions (green) and dark and bright biexcitons (red). The excited bright trions and excitons are denoted by T* and B*. The dark exciton (Xd) energy is marked as a reference point
.