Effect of spin polarization on exciton formation in conjugated polymers

Motivated by recent experimental researches in spin polymer light emitting diodes, we investigate spin-related exciton formation from recombination of spin polarons. The simulations are performed based on an extended version of the one-dimensional Su–Schrieffer–Heeger model combined with the Hubbard model. It is found that when the electron–electron interactions are neglected, the yield of singlet excitons is dependent upon cosine of the spin polarization angle of two polarons. However, in the presence of on-site electron–electron interactions, the formation of singlet excitons will be significantly depressed, which is due to the broken of spin degeneracy.