White-Light-Emitting Diodes from Single Polymer Systems Based on Polyfluorene Copolymers with Quinoxaline Derivatives

Abstract

White polymeric light-emitting diodes (WPLEDs) from a single polymer system were developed by incorporating 2,3-bis(4-methyloxyphenyl)quinoxaline and 5,8-bis(N,N-diphenylamino)-2,3bis(4-methyloxyphenyl)quinoxaline into poly(9,9-dioctylfluorene). All copolymers showed good thermal stability with 5% weight loss temperatures above 420 °C, and glass transition temperatures ranged from 86 to 143 °C. Electroluminescence (EL) devices with indium tin oxide/poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonic acid)/emission layer/Ca/Ag were found to emit white light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.40) and (0.30, 0.36). These devices exhibit a highest brightness of 12 300 cd/m 2 and a maximum current efficiency of 2.56 cd/A.

Light-Emitting Devices with Conjugated Polymers

“…The improvement to these molecular structures plays a very important role for both the luminance efficiency and the stability of the device. These materials were highlighted in the series of PPV, poly (9,9-dialkyfluorene) (PFO), polycarbazole (PCB) and their derivatives and copolymers [ 9 – 22 ]. The synthetic design of the conjugated polymers, in particular the importance of controlling molecular weight, polydispersity and the suppression of defects, has recently been reviewed in detail by Holmes et al [ 23 ].…”

Single-Component Color-Tunable Gd(pic)3: Eu3+ Phosphor Based on a Metal–Organic Framework for Near-UV White-Light-Emitting Diodes

“…Up to now, researchers have been doing a lot to develop novel phosphors for single-component n-UV WLEDs, 16 such as inorganic materials, 17−19 organic molecules, 20−22 polymers, 23−25 and hybrid inorganic–organic composites, and so forth. 26−29 In the past decades, metal–organic frameworks (MOFs) have recieved tremendous concern because of diverse structures and application prospects in magnetism, separation, gas storage, catalysis, and drug delivery, and so forth.…”

Photophysical and Electroluminescence Characteristics of Polyfluorene Derivatives with Triphenylamine

“…Red-green-blue emission from a single polymer was achieved recently from a star-shaped polymer [12], where PF provided emission in the blue, and modification in the core produced green emission, and finally, the addition of a dopant contributed the red emission. The dopant can consist of metal complexes, dye, or quantum dots that were incorporated into the polymer [11,12,13,14]. In order to stabilize the blue emission from PF, triphenylamine (TPA) has been used with PF.…”