Crosslinkable Hole‐Transport Layer on Conducting Polymer for High‐Efficiency White Polymer Light‐Emitting Diodes

Abstract

High‐efficiency white polymer light‐emitting diodes are demonstrated by using a hole‐injection/transport bilayer. The excellent solvent resistance of the fully crosslinked hole‐injection layer ensures the subsequent solution processing of the light‐emitting layer. High power efficiency can be achieved. The device also emits quite stable white light. The figure shows a schematic of the device and the chemical structure of the VB‐TCTA layer.

Long‐Lifetime Polymer Light‐Emitting Electrochemical Cells Fabricated with Crosslinked Hole‐Transport Layers

“…The synthesis and characterization of PS-TPD-PFCB and VB-TCTA were reported elsewhere. [22,23,26] The advantages of using these two materials include solution-processability and simple thermal crosslinking with no side products involved. Both PS-TPD-PFCB and VB-TCTA were dissolved in 1,2-dichloroethane, and the 0.5 weight percent solutions were spin-cast at 3000 rpm to form thin films on the PEDOT-PSS layer.…”

Efficient, Color Stable White Organic Light‐Emitting Diode Based on High Energy Level Yellowish‐Green Dopants

“…The applications require WOLEDs possess high efficiency, appropriate color temperature, high color rendering index, and high color stability. [1] Various approaches have been reported to improve the performance, which include doping of several fluorophors or phosphors in a single emitting layer (EML), [2][3][4][5][6][7][8] synthesis of polymers incorporating different color emitting moieties, [9][10][11] use of excimer or exciplex formed by one or two dopants, [12][13][14] stacked several organic light emitting diodes (OLEDs), [15][16][17] use of microcavity effect from single emission layer, [18] down conversion of blue light, [1,19] and multi-EML structure doped with different color emitting dopants. [20][21][22][23][24][25] Among them, multi-EML structure has advantages over other architectures in terms of efficiency and color controllability because the recombination current, singlet and triplet energy transfer and performance of each layer can be controlled by layer thickness, doping concentration and charge blocking layers.…”

Controlling Polymer Solubility: Polyfluorenes with Branched Semiperfluorinated Side Chains for Polymer Light‐Emitting Diodes

“…For the deposition of discrete new layers, intermixing and dissolution of the previous layer must be prevented. To overcome these difficulties, many different approaches, such as cross-linking of the lower layer, [9,10] liquid buffer layers, [11,12] or the use of orthogonal solvents, [6,7,13] have been performed. Orthogonal solubility was established for polar/nonpolar solvent pairs with polyethylene glycol (PEG)-substituted conjugated polymers as the polar soluble component.…”