New light emitting materials: Alternating copolymers with hole transport and emitting chromophores

Abstract

ABSTRACT:A new type of novel high-efficiency light-emitting nitrogen-containing poly-(phenylene vinylene) (PPV)-related copolymers, which have hole-transfer moieties such as triphenylamine (TPA) and conjugated aromatic units such as 4,4Ј-biphenylene, 1,4-phenylene, 2,5-dimethyl-1,4-phenylene, 1,4-or 1,5-naphthylene, and 9,10-anthrylene, was designed and synthesized by the well-known Wittig-Hornor reaction. The resulting alternating copolymers were highly soluble in common organic solvents. They can spin-cast onto various substrates to give highly transparent homogeneous thin films without heat treatment. The introduction of TPA units in the PPV backbone improved processibility and limited the -conjugation length. Furthermore, the additional -electron delocalization between the lone-paired electron in the nitrogen atom and -electrons in the conjugated units contributed to the improvement of the fluorescence quantum yields of these copolymers. All these alternating copolymers except TPA-PAV have high-efficiency photoluminescence and they are very promising for light-emitting diodes (LEDs). It is very promising that TPA-PAV will emit white light when used in LED device due to the broad emission spectra. The origin of the broad spectrum is contributed by the charge-transfer complex formation, which can be proved by the absorption and emission spectra of TPA-PAV solutions. When the aromatic units were 1,4-phenylene, 1,4-or 1,5-naphthylene, 4,4Ј-biphenylene, and 9,10-anthrylene, respectively, with increase of the capability to accept electrons in aromatic units, the charge transfer from TPA to aromatic units occurred; consequently, the fluorescence quantum yield decreased. The introduction of the alkoxy-substitute group on the aromatic units in the polymer backbone caused the red shift of the absorption and emission spectra of the copolymers due to the stronger delocalization of the -conjugated system.

Synthesis and photopolymerization of new triphenylamine-based oxiranes

“…4,4 -Di (diphenylamino) biphenyl (7) was synthesized by a procedure described elsewhere [7]. 4-Formyltriphenylamine (1) and 4-(4-formylphenylphenylamino)-4 -(diphenylamino) biphenyl (8) were synthesized by the method of Vilsmeier as described elsewhere [8,9]. 4-(Hydroxymethyl) triphenylamine (2) and 4-(4-hydroxymethylphenylphenylamino)-4 -(diphenylamino) biphenyl (9) were synthesized by reduction of 1 and 8, respectively, with sodium borohydride [10,11].…”

“…4-(Hydroxymethyl) triphenylamine (2) and 4-(4-hydroxymethylphenylphenylamino)-4 -(diphenylamino) biphenyl (9) were synthesized by reduction of 1 and 8, respectively, with sodium borohydride [10,11]. 4,4 -Di(hydroxymethyl) triphenylamine (5) was synthesized by a two-step route involving formylation of triphenylamine [8] and reduction of 4,4 -diformyltriphenylamine (4) with sodium borohydride [10].…”

Direct Evidence of Photoinduced Charge Transfer from Alternating Copolymer to Buckminsterfullerene

“…TPA-PAV (Scheme 1) was synthesized as previously reported, [11,12] and the synthesis of the monomers is shown in Scheme 2 including 9,10-bis(chloromethyl)anthracene (A), the dialdehydation of triphenylamine (B), and the preparation of bis(dibutyl phosphate). A brief description of the syntheses follows.…”

Photoinduced Intramolecular Charge Separation at the Repetition Units of Light-Emitting Alternating Copolymers

“…Correspondingly, our method is to incorporate hole transporting species, e. g. triphenylamine (TPA) into PPV backbone to obtain the nitrogen-containing PPVrelated copolymers in the main chain, which may bear hole migration moieties and conjugated aromatic units such as 1,4-phenylene (TPA-PPV), 1,4-or 1,5-naphthylene (TPA-PNV) and 9,10-anthrylene (TPA-PAV). [9] This intention is based on the fact that triphenylamine has the Full Paper: Light-emitting nitrogen-containing poly-(phenylene vinylene) PPV-related copolymers are synthesized by the well-known Wittig-Horner reaction. The alternating copolymers have hole-transporting moieties such as triphenylamine (TPA) and conjugated aromatic units such as 1,4-phenylene, 1,4-or 1,5-naphthylene and 9,10-anthrylene.…”