Theoretically, the chirality of the chiral layer has an apparent impact on the spin polarization direction of the charge carriers passing through it. When a chiral layer with (S)-enantiomer is located adjacent to another chiral layer with (R)-enantiomer, the spin polarization direction of the charge carriers should be notably influenced by altering the thickness of the chiral layers, leading to varied CP-EL signals. Thereby, to have a deeper understanding on how the CISS effect of the chiral layer influences the CP-EL property of the achiral layer, a set of experiments involving modulations on the chirality and thickness of the chiral layer are conducted. The device configuration is designed as ITO/HATCN (5 nm)/TAPC (50 nm)/TcTa (5 nm)/mCP (5 nm)/(S)-PCNTPA (6 nm)/(R)-PCNTPA (x nm)/30 wt% BDMAC-XT: CBP (14 nm)/TmPyPB (40 nm)/LiF (1 nm)/Al (Fig. and), where the thickness of (S)-PCNTPA layer is set as 6 nm, while that of (R)-PCNTPA layer is altered progressively (x = 0, 2, 4, 6, 8 and 10). When x is 0, the device shows an apparent CP-EL signal, with a gEL value of -1.0 × 10 -3 , consistent with the previous results. However, for x = 2, 4 and 6, the devices exhibit almost no CP-EL signals because of the opposite interference of the chiral layers with opposite chirality, by which the spin polarization direction of charge carriers becomes randomized as current traverses through two chiral layers with opposite chirality, (S)-PCNTPA/(R)-PCNTPA. Significantly, when x is increased to 8 and 10, the devices display evident opposite CP-EL signals in comparison with that at x = 0 (Fig. and, and Supplementary Fig. ). This outcome indicates that the spin polarization direction of charge carriers is realigned when passing through the thicker (R)-PCNTPA chiral layer, leading to the flip of the CP-EL signals. The obvious switch in the gEL value from negative to positive as the thickness of the (R)-PCNTPA chiral layer increases proves that the green CP-EL of achiral layer is triggered by the spin-polarized charge carriers generated by the chiral layer, and offers further evidence for the CISS effect of (S)-/(R)-PCNTPA chiral materials.