The pyrene excimer is larger and more strongly bound than the benzene excimer, which uncorrected TD-DFAs fail to predict with errors ranging from 13.21 to 26.62 kcal/mol (Fig. ). For this larger system, dispersion-corrected TD-DFAs offer some improve- Both dispersion corrections considerably improve the B3LYP dissociation energy to within 2.91 kcal/mol accompanied by an improved r e with an overestimation of 0.12 Å. Dispersioncorrected CAM-B3LYP does not show the same improvement to the dissociation energy as its global counterpart, yielding an underestimation of up to 8.93 kcal/mol for D e and an overestimation of r e by 0.14 and 0.13 Å for D3(BJ) and D4, respectively. B2PLYP-D3(BJ) and -D4 give dissociation energies with errors comparable to dispersion-corrected B3LYP (underbound by 2.05 and 1.73 kcal/mol), but with a smaller geometry error (overestimation of 0.07 and 0.08 Å). Dispersion corrected ωB2PLYP offers only a small improvement to the uncorrected functional such that ωB2PLYP-D3(BJ) and ωB2PLYP-D4 underbind the pyrene excimer by 12.70 and 12.67 kcal/mol, respectively, and overestimate r e by 0.08 Å. A negligible impact of D3(BJ) and D4 on both ωB2PLYP and ωB2GP-PLYP has also been noticed in ground-state benchmarking on the complete GMTKN55 database and its NCI category. For the larger system size of the pyrene excimer, the groundstate dispersion corrections improve TD-DFA dissociation energies and equilibrium distances. This is likely why others have recommended the use of ground-state optimised dispersion corrections for the calculation of this excimer's dissociation energy. While DFT-D type dispersion corrections offer some improvement to the description of excimer binding, their performance is far from a black-box solution for excited states. Inconsistent improvement by ground-state dispersion corrections for excited states reinforces the need for state-specific dispersion corrections for reliable and predictive TD-DFT methods.