Synthesis and Luminescent Properties of Blue Light Emitting Polymers Containing both Hole and Electron Transporting Units

Abstract

Poly[(oxy‐4,4′‐octafluorobiphenyloxy)‐1,4‐phenylenevinylene‐2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene‐1,4‐phenylene], POFB‐MEH‐PPV, poly[(oxy‐4,4′‐octafluorobiphenyloxy)‐1,4‐phenylenevinylene‐9,9‐dihexyl‐2,7‐fluorenediylvinylene‐1,4‐phenylene], POFB‐PF, and poly[(oxy‐4,4′‐octafluorobiphenyloxy)‐1,4‐phenylenevinylene‐N‐ethylhexyl‐3,6‐carbazolevinylene‐1,4‐phenylene], POFB‐PK, were synthesized by the well‐known Wittig condensation polymerization. We incorporated the high electron affinity (octafluorobiphenyl) and hole‐transporting (carbazole, fluorene, and dialkoxyphenyl) units into the conjugated main chain. The conjugation lengths are limited to the blue‐emission region by ether linkage. The resulting polymers were completely soluble in common organic solvents such as chloroform, 1,2‐dichloroethane, and cyclohexanone, and exhibited good thermal stability up to 300°C. The synthesized polymers showed UV‐visible absorbance and photoluminescence (PL) in the ranges of 350–385 nm and 460–490 nm, respectively. The fluorene or carbazole containing POFB‐PF and POFB‐PK showed blue photoluminescence peaks at 470 and 460 nm, respectively. The single‐layer light‐emitting diode was fabricated in a configuration of ITO (indium‐tin oxide)/polymer/Al. Electroluminescence (EL) emission of POFB‐PF and POFB‐PK were shown at 475 and 458 nm, respectively, corresponding to the pure blue emissions. And, a dialkoxyphenyl containing POFB‐MEH‐PPV showed greenish blue light at 494 nm. But, LED devices from synthesized polymers showed poor device performance and high turn on voltage. So, we fabricated light‐emitting diodes (LEDs) from blend polymers composed of poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV) and POFB‐MEH‐PPV (POFB‐PF or POFB‐PK) as the emitting layers. The EL emission maxima of each blend polymers were in the range of 573–591 nm, which indicates that the emission is mainly due to MEH‐PPV and POFB‐MEH‐PPV (POFB‐PF or POFB‐PK) contributes to the enhancement of the luminescence. And each blend polymers exhibited higher EL quantum efficiency compared with MEH‐PPV at the same current density.

Synthesis and Luminescent Properties of Tetrafluorophenyl Containing Poly(p-phenylenevinylene) Derivatives

“…In addition, PCTF-PPV and PMTF-PPV show weak but clear absorption peaks at about 965 cm -1 corresponding to the out-of-plane bending mode of the trans-vinylene bonds. This proves the formation of vinylene double bond and consequently the polymerization reactions have been successful [6,20].…”

“…In addition, by fluoro group substitution, PMTF-PPV showed far more red-shifted emission at 580 nm than p-PMEH-PPV. The emission maximum of PMTF-PPV is almost similar the to that of well know MEH-PPV polymer [20]. We found that the tetrafluorophenyl linkages effectively extend …”

Impact of position of electron withdrawing cyano groups on nonlinear optical properties of centrosymmetric donor‐π‐acceptor system

“…The synthetic procedures involved in the preparation the reported compounds are depicted in Scheme . 2,2′‐(2,5‐Dimethoxy‐1,4‐phenylene)diaceto nitrile ( 1 ), 4‐ N,N ‐dimethyl‐aminobenzyl cyanide ( 3 ), 1,4‐bis(chloromethyl)‐2,5‐dimethoxy benzene ( 4 ), 1,4‐dihydroxymethyl‐2,5‐dimethoxybenzene ( 5 ), and 2,5‐dimethoxy benzene‐1,4‐dialdehyde ( 6 ) were prepared according to the literature synthetic method . 4‐( N,N ‐dimethylamino)‐benzaldehyde ( 2 ) and 1,4‐dimethoxybenzene were purchased from the Aldrich and used as received.…”

Conjugated Silole and Carbazole Copolymers: Synthesis, Characterization, Single‐Layer Light‐Emitting Diode, and Field Effect Carrier Mobility

“…Recently, increasing interest has been paid to conjugated and non‐conjugated carbazole‐based polymers 6–17. These polymers normally possess high hole affinity and good hole‐transporting ability for PLED applications 18–22. The emission color of the conjugated carbazole‐based copolymers could be largely tuned through judicious selections of comonomers 18–31.…”

“…These polymers normally possess high hole affinity and good hole‐transporting ability for PLED applications 18–22. The emission color of the conjugated carbazole‐based copolymers could be largely tuned through judicious selections of comonomers 18–31. Since the copolymers normally possess HOMO levels of ≈−5.2 eV, holes can be directly injected from ITO anode into the copolymers.…”