High‐efficiency poly(phenylenevinylene)‐co‐fluorene copolymers incorporating a triphenylamine as the end group for white‐light‐emitting diode applications

Abstract

We have synthesized a series of PPV copolymers and investigated the relationships between their chemical structures, thermal stabilities, and optoelectronic properties. Initially, we monitored the effects of the end group and the molecular weight on the behavior of polymer light emitting diodes (PLEDs) prepared from a series of oligo(phenylenevinylene) (OPV)‐fluorene luminescent copolymers. We found that the nature of the end‐capping group was an important factor affecting the luminescence properties of devices, which were improved especially when applying a triphenylamine end group. The molecular weight mainly affected the film quality of the manufactured device; that is, it improved to a certain degree when the molecular weight increased. Based on the luminescence conversion mechanism, we used a simple spin‐coating process to fabricate a high‐efficiency LED displaying white‐light CIE 1931 (coordinates of 0.31, 0.34). The device exhibited a high current‐efficiency of 3.5 cd/A and a brightness of 973 cd/m2. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4504–4513, 2007

Synthesis and white electroluminescent properties of multicomponent copolymers containing polyfluorene, oligo(phenylenevinylene), and porphyrin derivatives

“…The CIE coordinates of the EL spectral emissions from the P2 device at a bias of 9 V were (0.29, 0.30), which is located in the white light region and very close to the CIE coordinates for pure white light point (0.33, 0.33). Both of the copolymers exhibit very lower turn‐on voltages (≤6 V) and higher maximum brightnesses in comparison with the previous study of fluorene‐ co ‐porphyrin polymers,40 and fluorene‐ co ‐oligo(phenylenevinylene) polymers 45. The maximum brightnesses of these polymers are also higher than the polyfluorene derivatives merely containing oligo(phenylenevinylene) dopants, which were reported previously by our group 33.…”

“…The multicomponent copolymers were prepared according to the Suzuki polymerization method. When the polymerization was complete, the end groups were blocked with 4‐bromo‐triphenylamine or 4‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)‐ triphenylamine, because the residual functional end groups could lower the EL performance of the device based on the copolymers,45 while the triphenylamine moieties end‐capper as the hole transporting moieties (HTM) could improve the device performance significantly, which has been demonstrated by Neher and coworkers 46. A thin‐layer chromatography (TLC) was used to inspect the purity of porphyrin‐containing copolymers, and none of the model compound 2 ( Por ) was inspected in the resulting copolymers.…”

Synthesis and electro‐optical properties of polyfluorene modified with randomly distributed electron‐donor and rotaxane electron‐acceptor structural units in the main chain

“…The copolymerization of PFO with electron‐rich and electron‐deficient groups, resulting in donor‐acceptor (D‐A) structural units, is of current interest because the resulted intramolecular charge transfer complexes (ITC), which can facilitate a small band‐gap with improved charge‐injection and charge‐transport properties 13, 14. The incorporation of the nonrigid groups of electron‐donating triarylamine (TA), either as additional repeating units along macromolecular chains or as pendant groups, leads to better fluorescence efficiency and hole mobility in solid state 15–18. ITC studies of electron‐deficient fluorene derivatives, that is, 9‐dicyanomethylfluorene, proved the ability of this moieties to tune the band‐gaps and the electron‐transport properties 19–21…”

Synthesis and characterization of a novel electrochromic aromatic polyamide from AB‐type triphenylamine‐based monomer

“…Recently triphenylamine (TPA) derivatives have extensively been investigated for hole transporters, light emitters, and photoconductors 7–21. TPA also can be considered as a well electrochromic material by easily oxidized to form radical cations with a noticeable change of coloration.…”