Metal Complexes, Methods, and Uses Thereof

A metal complex comprising:

• a transition metal selected from the group consisting of platinum (II), palladium (II), nickel (II), manganese (II), zinc (II), gold (III), silver (III), copper (III), iridium (I), rhodium (I), and/or cobalt (I);
• and
• a tetradentate ligand bonded to the transition metal,
• wherein:
• the metal complex has a lowest triplet excited state and a lowest singlet excited state,
• the lowest triplet excited state has a lower energy level than the lowest singlet excited state,
• the lowest triplet excited state is associated with phosphorescence, and
• a transition from the lowest triplet excited state to the lowest singlet excited state yields delayed fluorescence from the lowest singlet excited state.