Single-layer triplet white polymer light-emitting diodes incorporating polymer oxides: Effect of charge trapping at phosphorescent dopants

Abstract

This paper describes the effects of charge trapping on the device performances of triplet polymer light-emitting diodes (PLEDs) after the cathode contact had been improved through the blending of poly(ethylene glycol) (PEG) into the active layer. The external quantum efficiency (EQE) was enhanced when the dopant tended to trap electrons. In contrast, we observed no EQE enhancement for the device featuring a hole-trapping dopant. Because PEG promoted electron injection, more electrons were trapped in the triplet molecules, thereby enhancing the probability of recombination. Finally, after incorporating PEG, we further achieved white PLEDs exhibiting both high EQE and high power efficiency.

Nanoscale functional interlayers formed through spontaneous vertical phase separation in polymer photovoltaic devices

“…[17][18][19] Therefore, we suspect that this reduction in device resistance was due mainly to decreased contact resistance between the active layer and the Al electrode after the chemical interaction between PEG and Al. [17][18][19][20][21] In contrast, a tremendous drop in device performance-to below that of the standard device-occurred when we increased the concentration of PEG to 10 wt% (Fig. 2).…”

Efficient green-phosphorescent light-emitting diodes based on polymeric binary-host systems

“…The single-layer polymer phosphorescent lightemitting devices based on a green-emitting iridium complex (Ir(mppy) 3 ) and a polymer host (PVK) co-doped with electrontransporting (PBD) and hole-transporting molecules (TPD) have also been confirmed by Yang and Neher [19]. Chen et al [20] fabricated blue, red and white triplet PLEDs incorporating a polymer surfactant, PEG, as an additive in the EL layer.…”

Tunable microcavities in organic light-emitting diodes by way of low-refractive-index polymer doping

“…Prior to use, the substrates were further treated with UV-ozone. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) was spin coated onto the ITO substrates and then baked at 120°C for 1 h. The emission layer comprised poly(vinylcarbazole) (PVK), 2-(4-biphenyl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD), and tris[2-(4-tolyl)phenylpyridine]iridium [Ir(mppy) 3 ] at a weight ratio of PVK:PBD:Ir(mppy) 3 = 70:29:1 [20][21][22]. The emission layer was deposited on top of the PEDOT:PSS layer from a solution of 1,2-dichlorobenzene inside a N 2 -filled glovebox.…”