Solvent Effects on the Architecture and Performance of Polymer White‐Light‐Emitting Diodes with Conjugated Oligoelectrolyte Electron‐Transport Layers

High-efficiency conjugated-polymer-hosted blue phosphorescent light-emitting diodes

“…However, in fabricating functional layer on top of the emissive layer (EML), electron-transporting material would be selectively removed resulting in poor luminescent efficiency [14,15]. For example, Xu et al [14] found that the spincoating of the electron-injection layer from the methanol solution was capable of selectively extracting the electrontransporting material, 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7), of the EML, PVK : OXD-7 : FIrpic : (piq) 2 Ir(acac), leading to poor PLED performance.…”

Enhancing the performance of polymer light-emitting diode via methanol treatment

“…Since most emissive polymers are soluble only in nonpolar-solvent, functional layers are usually fabricated from polar-solvent solution, such as alcohols. But studies show that polar solvents, such as methanol and ethanol, have a bad effect on the performance of phosphorescent PLEDs [12,13]. Xu et al [12] found that methanol is capable of extracting a critical component of the emissive layer (EML) blend, the electron transport material 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7), resulting in low device performance.…”

“…But studies show that polar solvents, such as methanol and ethanol, have a bad effect on the performance of phosphorescent PLEDs [12,13]. Xu et al [12] found that methanol is capable of extracting a critical component of the emissive layer (EML) blend, the electron transport material 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7), resulting in low device performance. Meanwhile, Zhang et al [13] reported a 4.2 times increase in the device's luminous efficiencies with ethanol/water solution as the electron injection layer instead of pure ethanol solution.…”

“…To achieve highly efficient light-emitting, multilayered structures were commonly used with the addition of electron injection/transport or hole injection/transport layers [6][7][8][9][10][11][12][13]. However, unlike small molecular devices, where multi-layer structures with well-defined individual layers can be fabricated using vacuum deposition methods, it is a big challenge to fabricate multilayered PLEDs.…”

Ether solvent treatment to improve the device performance of the organic light emitting diodes with aluminum cathode

“…Since most organic light-emitting materials have low LUMO (lowest unoccupied molecular orbital) level, the injection of electrons from the cathode is extremely critical to balance the charges. Reducing the electron injection barrier by modifying the organic/metal interface, such as the deposition of low work-function metals [4,5], alkaline halides and alkali-earth halides [6], metallic compounds [7,8], water/alcohol soluble polymers like conjugated polyelectrolytes or their neutral precursor [9][10][11][12], non-conjugated interlayer materials like polyethylene imine (PEI) [13,14], and even solvents [15,16], has been proved to be an effective approach.…”