SISSO models were trained following the same procedure used in Ref. . The same primary features were used, summarized in Table (also provided in the PAH101 dataset 110 ). The primary features include both single molecule and crystal properties. DFT primary features were calculated with the FHI-aims code using the Perdew-Burke-Ernzerhof (PBE) exchangecorrelation functional, as described in Ref. . The DFT estimates for the SF driving force of the single molecule and crystal (DF_s and DF_c), which were used as primary features in Ref. , were excluded because they are not relevant to the properties studied here. For the singlet-triplet gap model, two additional primary features were included: the DFT estimates for the single molecule and crystal singlet-triplet gap (∆ST S and ∆ST C ). These were evaluated by subtracting the molecule/crystal triplet formation energy, as an approximation for the triplet excitation energy, from the molecule/crystal PBE gap, as an approximation for the singlet excitation energy (i.e., ∆ST S = Gap S -ET S and ∆ST C = Gap C -ET C ). The total number of SISSO primary features was thus 14 for the singlet exciton energy, triplet exciton energy, and singlet exciton binding energy models and 16 for the singlet-triplet gap models. The same 10 structures as in Ref. were withheld as an unseen validation set and the remaining 91 structures were used for model training.