Recombination is spin dependant

LED’s require injection of holes at one electrode and electrons at the other.

If no spin polarization

An eigenstate requires:

triplet

triplet

mixed

mixed

triplet

singlet

triplet

singlet

triplet

triplet

Three states with s = 1 (triplet) and one state with s = 0 (singlet) or, in the absence of other effects, 75% triplet and 25% singlet recombination