A new, but archetype compound [Ir(ppy-F<sub>2</sub>)<sub>2</sub>Me<sub>4</sub>phen]PF<sub>6</sub>, where ppy-F<sub>2</sub> is 2-(2',4'-
fluorophenyl)pyridine and Me<sub>4</sub>phen is 3,4,7,8-tetramethyl-1,10-phenanthroline, was synthesized and used
to prepare a solid-state light-emitting electrochemical cell (LEC). This complex emits blue light with a
maximum at 476 nm when photoexcited in a thin film, with a photoluminescence quantum yield of 52 %.
It yields an efficient single-component solid-state electroluminescence device with a current efficiency
reaching 5.5 cd/A and a maximum power efficiency of 5.8 Lm/Watt. However, the electroluminiscence
spectrum is shifted with respect to the photoluminiscence spectrum by 80 nm resulting in the emission of
green light. We demonstrate that this unexpected shift in emission spectrum is not originating from the
way of excitation, nor from the presence of large concentrations of ions, but is related to the concentration
of the ionic transition metal complex in the thin film. The origin of the concentration dependent emission
is extensively commented and argued to be related to the population of either <sup>3</sup>LC π-π* or <sup>3</sup>MLCT triplet
states, in diluted and concentrated films, respectively. Using quantum chemical calculations we
demonstrate that three low-energy triplet states are present with only 0.1 eV difference in energy and that
their associated emission wavelengths differ by as much as 60 nm from each other.