Near-IR luminescence and photophysics of Yb-porphyrinate complexes

Near-infrared photoluminescence of a series of Yb³⁺-porphyrinate complexes were studied. The complexes can be efficiently excited with visible light and give characteristic Yb³⁺ emission. The photoluminescence efficiency was greatly affected by the structure of complexes, especially the side moiety of the porphyrin ring. One of the complexes gives a well-split spectrum at room temperature, and the intensity shift of the split peaks as a function of temperature can be described by the Maxwell-Boltzmann law. The transitions were discussed and a proposed energy level diagram of Yb³⁺ is proposed. Good agreement was obtained between the experimental results and theory.