"Excitons in Transition Metal Dichalcogenide van der Waals Heterostructures" (My Dissertation)

This was mostly a practice talk but since people have been watching it I want to emphasize that the main purpose of using Van der Waals structures is that it increases the binding energy so that indirect excitons are stable at room temperature. Both binding energy and the temperature at which spontaneous coherence is expected happen are both driven by the exciton bohr radius which is much smaller for TMD Van der Waals quantum wells than conventional quantum wells.I do talk about it but I don't mention it explicitly in the first few minutes or when I talk about the limits of conventional quantum well structures.

why always 2 electrons and 1 "hole" or vice versa with trion's ?. why not 3 or more ?.