Intra-molecular CT states play an important role in the photo-physical processes and eventual device performances of organic electroluminescent materials such as organic thermally activated delayed florescence (TADF) and radical emitters. For organic TADF emitters, we have shed light on how the energy levels and excitation characters of intra-molecular CT states impact electronic-structure parameters such as singlet-triplet energy gap, spin-orbit coupling, transition dipole moment, and thus reverse intersystem crossing and radiative decay processes. For organic radical emitters, we have designed donor-acceptor neutral radicals based on the electron-poor perchlorotriphenylmethyl (PTM) or tris(2,4,6-trichlorophenyl)methyl (TTM) radical moiety combined with different electron-rich groups. Experimental and quantum-chemical studies demonstrate that the molecules do not follow the Aufbau principle: The Singly Occupied Molecular Orbital (SOMO), mainly localized on the PTM [TTM] segment, is found to lie below the Highest (doubly) Occupied Molecular Orbital (HOMO), mainly localized on the donor segment. Such the non-Aufbau behavior in the organic radical emitters is resulted from a high-energy CT state. These donor-acceptor radicals provide a remarkable combination of strong D1-to-D0 emission yield (up to 54%) and high photo-stability (e.g., the half-lives reach up to several months under pulsed UV laser irradiation). Organic light-emitting diodes (OLEDs) based on a radical emitter show near-infrared (NIR) emission with a high maximal external quantum efficiency of 4.0 %.