  Carbene-Metal-Amide light-emitting diodes have recently shown internal
quantum efficiencies approaching 100%, and there has been substantial debate
concerning the cause of their exceptionally high efficiency. Here we present a
theoretical description of CMAs, showing how a simple three-atom model can
predict the form of the HOMO and LUMO, determine the polarization of
transitions and the feasibility of spin-orbit coupling, as well as the
qualitative dependence of excited state energies and oscillator strength on the
twist angle. These results clarify many of the claims concerning CMAs and pave
the way for the design of more efficient devices.

Chemical Physics;Materials Science