A Mononuclear [PtCl(tpy)]PF₆ Complex for a Yellow Emitting Solution-Processable Organic Light Emitting Diode

We report square planar mononuclear Pt(II)-complexes of terpyridines in the form of [PtCl(L1/L2)]PF₆ as phosphorescent emitters (where L1 = 4-(3-pyridine)2,2':6',2''-terpyridine and L2 = 4'-(3-pyridinyl)-4,4''-di(tert-butyl)-2,2':6'2''-terpyridine). Complex 2 showed emission at 534 nm in the DCM solution with photoluminescence quantum efficiency (Φ_PL) = 14%, while in the mCBP host (5-wt % doped), the emission shifted to 584 nm with Φ_PL = 37.8% and a phosphorescence lifetime (τ_phos) of 37.8 μs. Complex 2 in mCBP was used to fabricate a solution-processed phosphorescent organic light-emitting diode (PhOLED) which showed maximum external quantum efficiency (EQE_max) = 7.4% with yellow emission at λ_EL = 570 nm and exhibited a low efficiency roll-off with an EQE drop to 7.0% at 1000 cd/m².