The molecules discussed so far belong to the D 3h point group and have a low-energy dark doublet ( 2 A ′′ 2 ) state that gets stabilized by the increasing number of aza nitrogens on the molecular rim. In order to further investigate the rim role in phenalenyl radicals, we decorated the external edge of PLY with an increasing number of aza nitrogen atoms, as shown in Fig. . All spectral features shift to the red as the number of N atoms on the external rim increases (see Fig. Results discussed so far demonstrate the utility of the PPP model and |⟨ D⟩| in predicting radicals with significantly broken particle-hole symmetry as extremely promising doublet emitters for OLED with 100% internal quantum efficiency. Realistic (all-electron) hamiltonians do not strictly obey particle-hole symmetry, as it is only an approximate symmetry. The half-filled (i.e., one electron per site on average) PPP model inherently assumes particle-hole symmetry. The degree to which this symmetry is preserved in more advanced all-electron Hamiltonians depends on how closely the assumptions of the PPP model align with the specific system being studied. The degree to which particle-hole symmetry is preserved di-minishes as these systems deviate from the idealized conditions assumed by the PPP model.