X with ΔE 5% U0+44 (in eV) in the ranges (-∞, -0.15) , [-0.15, 0.15] , and (0.15, ∞) , are denoted as "low", "mid", and "high", respectively. Combining these two classification criteria for X, the 132 X monomers (and their corresponding C22-X dimers) can be categorized into 6 subgroups: 43 in "bright-low", 28 in "bright-mid", 30 in "bright-high", 6 in "dark-low", 6 in "dark-mid", and 19 in "dark-high". The distribution of oscillator strength of the monomer X, TDM-parallel C22-X, and TDM-perpendicular C22-X are summarized in Figure . For the bright X monomers, the most significant trend is that all three subgroups (bright-low, brightmed, and bright-high) have the dimer's oscillator strengths lower than that of monomers X and C22, but the decrease is most significant for the "bright-mid" group regardless of the monomer S1 TDM orientation. We found possible explanations for this trend by analyzing the diabatic state contributions for these three groups in Figure . For a C22-X dimer in the brightmid subgroup (similar S1 energies of C22 and X), the dimer's S1 usually has similar contributions from the two LE states, together with an average 50% contribution from the CT states. In contrast, dimers in the bright-low and bright-high groups have brighter fluorescence because their excitons are dominated by LE states from the low-energy monomer, with less contribution from the CT states. In summary, the higher the CT component in the exciton, the more oscillator strength decrease was observed for the dimer compared to the monomer X, agreeing with the ACQ effect found in Section B. Another trend is the comparison between the parallel and perpendicular dimers. Compared with the TDM-perpendicular group, the oscillator strength of the "mid" TDM-paralleled group is significantly lower as the monomer TDM cancellation effect is maximized when two monomer LE states have aligned TDMs and similar diabatic state partitions. These observations correspond to the two sources of the ACQ effect mentioned in Section IV B & C: TDM cancellation and the involvement of CT states.