Iridium-complexed nanosize phosphors 3D-encapsulated with nine 3,6-di-tert-butyl-N-propyl-carbazole groups were constructed as host-dopant integrated systems, which achieved a high photoluminescence quantum yield beyond 70% from neat evaporated films, and an electroluminescence external quantum efficiency up to ∼8.5% and near-zero roll-offs at 1000 cd m(-2) from its dual-layer host-free light-emitting diodes.