posted on 2019-07-30, 17:41authored byFangfang Wei, Shiu-Lun Lai, Shunan Zhao, Maggie Ng, Mei-Yee Chan, Vivian Wing-Wah Yam, Keith Man-Chung Wong
A series
of luminescent cyclometalated rhodium(III) complexes have
been designed and prepared. The improved luminescence property is
realized by the judicious choice of a strong σ-donor cyclometalating
ligand with a lower-lying intraligand (IL) state that would raise
the d–d excited state and introduction of a lower-lying emissive
IL excited state. These complexes exhibit high thermal stability and
considerable luminescence quantum yields as high as up to 0.65 in
thin film, offering themselves as promising light-emitting materials
in OLEDs. Respectable external quantum efficiencies of up to 12.2%
and operational half-lifetimes of over 3000 h at 100 cd m–2 have been achieved. This work demonstrates a breakthrough as the
first example of an efficient rhodium(III) emitter for OLED application
and opens up a new avenue for diversifying the development of OLED
materials with rhodium metal being utilized as phosphors.