Application of [Pt(II)(di-tert-butylsalophen)] complexes within organic devices: Deep red emission, bistable light-emitting diodes and operational stability

Studies on [Pt(II)(di-tert-butylSalophen)] which is thermally stable (Td = 390°C) and displays a deep-red emission (Imax = 660 nm) are presented. Based on efficient energy transfer, this Pt(II) complex was used as a probe for exciton formation in organic light-emitting diodes (OLEDs). Electrical characterisation of host-guest system based devices showed that the presence of the Pt(II) complex within Tris-(8-hydroxyquinoline)aluminium matrix emissive layer, led to electrically active states. Upon electrical driving stress, modulation of the charge transport properties in devices was highlighted. Negative Differential Resistance (NDR) was observed and interpreted in terms of space charge effect. A figure of merit higher than 10
³
was achieved. Aging investigations showed a reversible electrical degradation and suggested that the Pt(II) complex would stabilise OLEDs performance. Moreover, internal electric field model was proposed to explain the observed polarisation/depolarisation phenomena.