Solution-processed small molecule-based blue light-emitting diodes using conjugated polyelectrolytes as electron injection layers

Abstract

Organic blue light-emitting diodes were studied using the solution processable small molecule 2,7-dipyrenyl-9,9′-dioctyl-fluorene (DPF) as the light-emitting material. The devices were fabricated in two simple structures: indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/DPF/LiF∕Al and ITO/PEDOT:PSS/DPF/PFN-BIm4∕Al, where PFN-BIm4 is poly[9,9′-bis[6″-(N,N,N-trimethylammonium)hexyl]fluorene-alt-co-phenylene] with tetrakis(imidazolyl)borate counterions. The LiF or PFN-BIm4 act as electron injection layers. The ITO/PEDOT:PSS/DPF/PFN-BIm4∕Al device, in which all organic layers are cast from solution, has a turn-on voltage of 3.8V, a luminance of 2000cd∕m2, and an efficiency of 0.6cd∕A. Using the PFN-BIm4 layer shows a significant improvement of the device performance when compared to the LiF layer.

Improved performance in flexible organic solar cells via optimization of highly transparent silver grid/graphene electrodes

“…25,33 The CPE layer functioned as an electron extraction layer via the formation of an interfacial dipole. 31 According to the energy band diagram, the hybrid SLG films exhibit similar work functions, which are comparable to the work function of conventional ITO anodes. 34 Figure 2(b) shows the optical transmittance and sheet resistances of SLG and SLG/Ag for various grid sizes.…”

Nondoped Deep‐Blue Organic Light‐Emitting Diodes with Color Stability and Very Low Efficiency Roll‐Off: Solution‐Processable Small‐Molecule Fluorophores by Phosphine Oxide Linkage

“…A number of solution-processed small molecules have been reported as blue electroluminescent materials. [26][27][28][29][30][31][32][33][34][35][36][37] However, deep-blue fluorescent SMOLEDs fabricated by spin-coating with stable color coordinates and high efficiency remain rare. It is not easy to design a small molecule that has both deep-blue emission and solution processability.…”

Fabrication and characterization of green light emitting diode

“…An important distinction of these 2 states is that the singlets can relax radiatively, whereas for the triplet states, this process is forbidden and, therefore, relaxation occurs via a nonradiative process. Simple spin statistics suggest that the ratio of singlets to triplets is 1:3, although studies show that this is not applicable in polymeric materials [9]. Phosphorescent OLEDs have been attracting much attention since the first report of Baldo et al [10].…”