Journal Article Research Support, Non-U.S. Gov't exciplex forming co-host blue OLEDs exciplex low refractive index ETL and HTL organic light-emitting diodes theoretical limit of EQE AC operation Coordination Complexes FIrpic N-heterocyclic carbene ligands Organic light-emitting diodes (OLEDs) TiO2 electrodes aluminum contacts ancillary ligands bis((4,6-difluorophenyl)pyridinato-N,C(2'))iridium(III)picolinate blue phosphorescent OLED carrier balance concentration quenching deep-blue phosphorescence delayed fluorescence electrochemiluminescence electrochemiluminescent devices exciplex forming co-hosts exciplexes fluorescent dyes high refractive index microstructure implants intrinsic absorption loss