Transient and DC electroluminescence of some new conjugated polymers

Transient Electroluminescence from Poly(phenylenevinylene)-Based Devices

“…The threshold voltage above which these EL spikes are observed is far below the threshold voltage under which the regular steady-state EL arises. [43] The EL spikes in thick films are independent of the polarity of the external voltage and of the pulse duration above 1 ms (Fig. 6, upper and middle panels).…”

“…The switching EL is quite strong and may lead to efficient and reliable PLEDs. Today, switching EL has been observed in devices based on PPV (this work) and ladder type PPV [43] but not on MEH-PPV. [94] It is not clear at the present time whether the switching effect is a property of systems containing traps, or an intrinsic phenomenon of a conjugated polymer.…”

“…In devices based on thicker films of PPV and ladder-type PPV copolymer [43] (200 nm to 1000 nm thick), light flashes, or EL spikes, are seen at both the turn-on and the turn-off of the voltage pulse as shown in Figure 6. The threshold voltage above which these EL spikes are observed is far below the threshold voltage under which the regular steady-state EL arises.…”

Metallocene-containing conjugated polymers

“…Ladder-type polymers are a class of two-dimensional (2D) materials which are intermediate between linear systems such as rigid rod conjugated polymers and three-dimensional (3D) structures as dendrimers. Ladder-type poly(p-phenylene)s (LPPPs) [195] with different functional groups 10a-10c such as carbazole units [196][197][198] and polyacene ladder polymers [199,200] demonstrate excellent optoelectronic properties and a very low amount of defects.…”

Strongly fluorescent ethylene-bridged poly(para-phenylene) ladder polymers

“…The synthetic procedure involves, in this case, the aryl-aryl-coupling of an alkyl-substituted 29,59-dibromoterephthalophenone with Ni[0]-reagents 7) followed by a subsequent polymer-analogous olefination according to McMurry. Unfortunately, this class of conjugated ladder materials displays a drastically reduced quantum efficiency of photo-and electroluminescence when compared to the methylene-bridged system 1 8) . One explanation for this surprising behavior is the known reduced PL efficiency of vinylene-bridged aromatic compounds, e.g.…”