Lanthanide 9-anthracenate: solution processable emitters for efficient purely NIR emitting host-free OLEDs†
Searching for new NIR emitting materials, lanthanide 9-anthracenates Ln(ant)3 were synthesized and thoroughly characterized. Ytterbium 9-anthracenate Yb(ant)3, that demonstrated the highest NIR luminescence efficiency, was successfully used as an emission layer of a host-free OLED and its electroluminescence quantum efficiency, corresponding to the sole band at 1000 nm, reached 0.21%. This performance could be achieved due to the high quantum yield of Yb(ant)3, which reached 1.5% and was increased up to 2.5% by partial Yb3+ substitution with Lu3+, as well as its high electron mobility due to the extended stacking in its crystal structure. The first gadolinium-based PHOLED was prepared based on Gd(ant)3.