Excited-states spectroscopies and its magnetic field effect of π-conjugated polymer-fullerene blends with below-gap excitation

•Below-gap photon excited polarons exhibit trap limited bimolecular recombination.•Below gap and above gap polarons are intrinsically same in millisecond time region.•Below gap polaron presents much weaker magnetic field effect than above gap one.•Much longer spin decoherent time could be achieved using below gap excitation.