Enhanced Photoluminescence Quantum Yields through Excimer Formation of Cyclometalated Platinum(II) N‑Heterocyclic Carbene Complexes

We
report a new class of C∧C* platinum­(II) complexes in
which excimer formation enhances the quantum yield while shortening
the phosphorescence lifetime. Selective excitation of the monomer
or dimer could be achieved at different wavelengths. These complexes
exhibit strong phosphorescent emissions in the blue part of the visible
spectrum around 450 nm with quantum yields of up to 93%. The emission
behavior is controlled through the steric demand of the substituents
at the 2,4-pentanedione ligand. We see dual emission with high photoluminescence
quantum yields (PLQY) from monomeric and aggregated excited states.

本研究报道了一类新型C∧C*铂(II)配合物，其中激基复合体的形成不仅提升了量子产率，亦缩短了磷光寿命。通过选择性地激发单体或二聚体，可以在不同的波长下实现。这些配合物在可见光光谱的蓝色区域，即约450 nm处展现出强烈的磷光发射，量子产率高达93%。其发射行为受制于2,4-戊二酮配体上取代基的立体需求。我们观察到，从单体和聚集激发态中产生了具有高光致发光量子产率（PLQY）的双重发射。