As the Rayleigh theorem holds for all Hermitian matrices, Eq. (3) holds with multiple LE states for each monomer involved, where the dimer fluorescence energy is lower than the lowest monomer LE state. Since E %& ' is highly positively correlated with the fluorescence energy E 5% ' , E 5% '. is expected to appear red-shifted compared with the fluorescence energy of the two monomers in most cases.