Color-tunable multilayer light-emitting diodes based on conjugated polymers

Abstract

Wide-range low-voltage continuous color tuning is achieved in multilayer light-emitting diodes based exclusively on the commonly used high-efficiency electroluminescent conjugated polymers. There are three layers for red, green, and blue emission, and one extra layer for electron blocking. The color of the emitted photon depends on the position of the electron-hole recombination. Due to the stronger field dependence of the electron mobility relative to the hole mobility, the recombination zone is pushed away from the cathode and concentrated in different emissive layers as the voltage increases.

Luminescence properties of poly(9,9-dioctylfluorene)/polyvinylcarbazole blends: Role of composition on the emission colour stability and electroluminescence efficiency

“…affinity (EA) of PFO to be 5.8 and 2.1 eV, respectively, in agreement with previous reports [23]. For PVK the reported values are 5.8 and 2.3 eV [24]. Based on these values, we do not expect significant variation of the hole-injection barrier from PEDOT (workfunction of ca.…”

Organic Light‐Emitting Diodes

“…However, polymer blends have generally been used to fabricated WPLEDs (as multilayer spin-coated polymer assemblies are difficult to obtain owing to close solubility parameters of materials), such as red, green, blue light-emitting three-polymer systems [257][258][259] and twopolymer blends containing macromolecular materials emitting two complementary colors [260][261][262][263][264][265]. For example, an efficient WPLED has been reported by Huang et al by blending polyfluorene V as a blue emitter, with a small percent of MEHPPV XIIas a source of orange-red light.…”

Tunable full-color emission of two-unit stacked organic light emitting diodes with dual-metal intermediate electrode

“…Voltage-controlled color tuning can be realized in a single unit OLED and has been reported in the devices using small molecules [1][2][3] and polymers [4][5][6]. We have reported a voltage-controlled color-tunable OLED based on a europium complex recently, in which the emitting color is tunable from red-to-blue or other designable color [7].…”