The generalized orbital interaction analysis was performed by the Multiwfn program. weakening of C-C bond on CH3 is more obvious. According to the electron density maps of the difference between molecules and corresponding cations, the electron loss mainly occurs above the plane of the benzene ring (𝜋 electron), and the acquisition of electrons occurs inside the plane during ionization. The change of geometry and electron density after ionization of meta and para is similar to that of ortho , as shown in Figure of the supplement. The isosurface of electron density before and after ionization of benzonitrile and o/m/p-cyanotoluene were shown in Figure . There is negligible deformation in the geometric structure of cyanotoluene after photoionization, the original symmetry of the system is not broken. As a result, the maximum of Franck-Condon factor appears near the threshold ionization energy, then it decreases with the photon energy (Figure -S4 in the supplementary materials). energy difference between the isomers in Table shows that the ocyanotoluene molecule presents as the most stable isomer among the three cyanotoluenes, while the m-cyanotoluene cation has the lowest energy after ionization. As a result, the AIE of ortho-isomer is similar to that of metaisomer. Also, due to the substitution of the electron donating group (methyl), the electron density of the benzene ring increases, which reduces the ionization energy of cyanotoluene relative to benzonitrile. The computed vertical ionization energie (VIE) of the four species are also shown in Table .