Novel Poly(p-phenylenevinylene)s with an Electron-Withdrawing Cyanophenyl Group

Abstract

Novel poly(p-phenylenevinylene) derivatives with an electron-withdrawing cyanophenyl group on the polymer backbone, poly[2-(2‘-ethylhexyloxy)-5-(4‘-cyanophenyl)-1,4-phenylenevinylene] (PEHCNPV) and poly[2-dimethyloctylsilyl-5-(4‘-cyanophenyl)-1,4-phenylenevinylene] (PSi8CNPV), were synthesized via the Gilch polymerization. These polymers were completely soluble in common organic solvents and showed good thermal stability up to 400 °C. Surprisingly, they showed very high glass transition temperatures (above 180 °C), indicating that electroluminescenece (EL) devices constructed from these polymers should have good thermal stability. The presence of the electron-withdrawing cyanophenyl group lowered the HOMO and LUMO energy levels of PEHCNPV and PSi8CNPV relative to those of common PPV derivatives. Light-emitting diodes (LEDs) with the configuration ITO/PEDOT/polymer/LiF/Al were fabricated using the novel polymers. The LED devices based on PEHCNPV and PSi8CNPV exhibited maximum electroluminescence at 546 and 513 nm, respectively. In particular, the LED device containing PSi8CNPV emitted pure green light with a CIE (Commission Internationale de L'Eclairage) chromaticity coordinate of (0.330, 0.599), which is very close to that of the standard green (0.30, 0.60) used for high definition television (HDTV), a maximum external quantum efficiency of 0.67%, and a maximum brightness of 2900 cd/m2.

Conjugated Organosilicon Materials for Organic Electronics and Photonics

“…39), were synthesized via the Gilch polymerization [175]. They showed very high glass transition temperatures (above 180 • C).…”

A New Polymeric Light‐Emitting Material with Pure Green Emission: Poly(fluorene‐alt‐quinoxaline) with Benzothiadiazole Groups in the Side Chain

“…[13][14][15][16][17][18][19][20][21] Recently, although there are some reports concerning the improvement of the chromaticity coordinate, the results are not satisfactory, due to either a complicated procedure for the synthesis of the polymers or impure emitting. [15][16][17][18][19][20][21] It is noted that the current color standard established by the Society of Motion Picture and Television Engineers (SMPTE) in 1979 (SMPTE-C, e.g., NTSC 1979) has been widely used in fields related to flat panel display. [22] Thus, investigation of the synthesis and properties of the materials that match with the standard is desirable.…”

“…n It has been found that most polymeric green emitters are derived from the fluorene-based polymers, and those polymers are usually constituted of a rich-electron fluorene unit and a deficient-electron unit. [13,[15][16][17][18][19][20] The green emission is attributed to intramolecular charge transfer. Of these polymers, the electron-withdrawing degree of the deficient-electron unit greatly affects the emission wavelength of the polymers.…”

Poly(p-phenylenevinylene)s Derivatives Containing a New Electron-Withdrawing CF3F4Phenyl Group for LEDs

“…Balancing the rates of injection of electrons and holes from opposite electrodes into the light-emitting polymer is required to achieve the high electroluminescence efficiency. Using additional organic charge-transporting layers, 19,20 and adjusting the energy band of the polymer by introduction of electron-withdrawing groups attached to the polymer backbone 21,22 were reported to overcome the imbalance of charge carrier injection or mobility. It was reported that the HOMO and LUMO energy levels can be lowered by the introduction of electron-withdrawing groups onto the arylene rings or the vinylene groups of the polymer.…”