Limits...
Design principle for increasing charge mobility of π-conjugated polymers using regularly localized molecular orbitals.

Terao J, Wadahama A, Matono A, Tada T, Watanabe S, Seki S, Fujihara T, Tsuji Y - Nat Commun (2013)

Bottom Line: The zigzag wires exhibited higher intramolecular charge mobility than the corresponding linear wires.When the length of the linear region of the zigzag wires was increased to 10 phenylene-ethynylene units, the intramolecular charge mobility increased to 8.5 cm(2) V(-1) s(-1).Theoretical analysis confirmed that this design principle is suitable for obtaining ideal charge mobilities in π-conjugated polymer chains and that it provides the most effective pathways for inter-site hopping processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan. terao@scl.kyoto-u.ac.jp

ABSTRACT
The feasibility of using π-conjugated polymers as next-generation electronic materials is extensively studied; however, their charge mobilities are lower than those of inorganic materials. Here we demonstrate a new design principle for increasing the intramolecular charge mobility of π-conjugated polymers by covering the π-conjugated chain with macrocycles and regularly localizing π-molecular orbitals to realize an ideal orbital alignment for charge hopping. Based on theoretical predictions, insulated wires containing meta-junctioned poly(phenylene-ethynylene) as the backbone units were designed and synthesized. The zigzag wires exhibited higher intramolecular charge mobility than the corresponding linear wires. When the length of the linear region of the zigzag wires was increased to 10 phenylene-ethynylene units, the intramolecular charge mobility increased to 8.5 cm(2) V(-1) s(-1). Theoretical analysis confirmed that this design principle is suitable for obtaining ideal charge mobilities in π-conjugated polymer chains and that it provides the most effective pathways for inter-site hopping processes.

No MeSH data available.


Related in: MedlinePlus

Conductivity transients and transient absorption spectroscopy (TAS) of films of 9 and 10.(a,b) Conductivity transients observed upon excitation of 355 nm at 6.5–7.3 × 1015 photons cm−2 in cast films of 9 and 10 with kinetic traces at absorption maxima (690 nm for 9 and 630 nm for 10) of the corresponding compounds. (c) TAS of a solid film of 9 upon exposure to 355 nm pulses at 5.0 × 1016 photons cm−2 recorded 2, 10 and 20 μs after excitation. (d) TAS of a solid film of 10 upon exposure to 355 nm pulses at 6.5 × 1016 photons cm−2 recorded at 2, 10 and 20 μs after excitation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3644079&req=5

f4: Conductivity transients and transient absorption spectroscopy (TAS) of films of 9 and 10.(a,b) Conductivity transients observed upon excitation of 355 nm at 6.5–7.3 × 1015 photons cm−2 in cast films of 9 and 10 with kinetic traces at absorption maxima (690 nm for 9 and 630 nm for 10) of the corresponding compounds. (c) TAS of a solid film of 9 upon exposure to 355 nm pulses at 5.0 × 1016 photons cm−2 recorded 2, 10 and 20 μs after excitation. (d) TAS of a solid film of 10 upon exposure to 355 nm pulses at 6.5 × 1016 photons cm−2 recorded at 2, 10 and 20 μs after excitation.

Mentions: Next, the potential for charge mobility of the prepared IMWs in the solid state was examined by simultaneously performing time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy measurements2122. The observed kinetic traces of the transient conductivity in solid films of 9 and 10 are shown in Fig. 4a. The para-PPE backbone in the linear IMW 9 exhibited effective photo-induced ionization upon excitation under ultraviolet exposure. This resulted in highly mobile positive holes (radical cations) on the backbones and stable scavenging of electrons by oxygen molecules. The kinetic traces of the transient absorption ascribed to the radical cations were evaluated quantitatively in their solid state using nano-second laser flash photolysis. Identical kinetic traces for the transient conductivity and optical absorption of the radical cations provided estimates of the intramolecular mobility of the holes on the backbone as μ ~0.75 cm2 V−1 s−1 for the linear PE backbones stretched and locked tightly by the insulating clads of CD, as in 9.


Design principle for increasing charge mobility of π-conjugated polymers using regularly localized molecular orbitals.

Terao J, Wadahama A, Matono A, Tada T, Watanabe S, Seki S, Fujihara T, Tsuji Y - Nat Commun (2013)

Conductivity transients and transient absorption spectroscopy (TAS) of films of 9 and 10.(a,b) Conductivity transients observed upon excitation of 355 nm at 6.5–7.3 × 1015 photons cm−2 in cast films of 9 and 10 with kinetic traces at absorption maxima (690 nm for 9 and 630 nm for 10) of the corresponding compounds. (c) TAS of a solid film of 9 upon exposure to 355 nm pulses at 5.0 × 1016 photons cm−2 recorded 2, 10 and 20 μs after excitation. (d) TAS of a solid film of 10 upon exposure to 355 nm pulses at 6.5 × 1016 photons cm−2 recorded at 2, 10 and 20 μs after excitation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3644079&req=5

f4: Conductivity transients and transient absorption spectroscopy (TAS) of films of 9 and 10.(a,b) Conductivity transients observed upon excitation of 355 nm at 6.5–7.3 × 1015 photons cm−2 in cast films of 9 and 10 with kinetic traces at absorption maxima (690 nm for 9 and 630 nm for 10) of the corresponding compounds. (c) TAS of a solid film of 9 upon exposure to 355 nm pulses at 5.0 × 1016 photons cm−2 recorded 2, 10 and 20 μs after excitation. (d) TAS of a solid film of 10 upon exposure to 355 nm pulses at 6.5 × 1016 photons cm−2 recorded at 2, 10 and 20 μs after excitation.
Mentions: Next, the potential for charge mobility of the prepared IMWs in the solid state was examined by simultaneously performing time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy measurements2122. The observed kinetic traces of the transient conductivity in solid films of 9 and 10 are shown in Fig. 4a. The para-PPE backbone in the linear IMW 9 exhibited effective photo-induced ionization upon excitation under ultraviolet exposure. This resulted in highly mobile positive holes (radical cations) on the backbones and stable scavenging of electrons by oxygen molecules. The kinetic traces of the transient absorption ascribed to the radical cations were evaluated quantitatively in their solid state using nano-second laser flash photolysis. Identical kinetic traces for the transient conductivity and optical absorption of the radical cations provided estimates of the intramolecular mobility of the holes on the backbone as μ ~0.75 cm2 V−1 s−1 for the linear PE backbones stretched and locked tightly by the insulating clads of CD, as in 9.

Bottom Line: The zigzag wires exhibited higher intramolecular charge mobility than the corresponding linear wires.When the length of the linear region of the zigzag wires was increased to 10 phenylene-ethynylene units, the intramolecular charge mobility increased to 8.5 cm(2) V(-1) s(-1).Theoretical analysis confirmed that this design principle is suitable for obtaining ideal charge mobilities in π-conjugated polymer chains and that it provides the most effective pathways for inter-site hopping processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan. terao@scl.kyoto-u.ac.jp

ABSTRACT
The feasibility of using π-conjugated polymers as next-generation electronic materials is extensively studied; however, their charge mobilities are lower than those of inorganic materials. Here we demonstrate a new design principle for increasing the intramolecular charge mobility of π-conjugated polymers by covering the π-conjugated chain with macrocycles and regularly localizing π-molecular orbitals to realize an ideal orbital alignment for charge hopping. Based on theoretical predictions, insulated wires containing meta-junctioned poly(phenylene-ethynylene) as the backbone units were designed and synthesized. The zigzag wires exhibited higher intramolecular charge mobility than the corresponding linear wires. When the length of the linear region of the zigzag wires was increased to 10 phenylene-ethynylene units, the intramolecular charge mobility increased to 8.5 cm(2) V(-1) s(-1). Theoretical analysis confirmed that this design principle is suitable for obtaining ideal charge mobilities in π-conjugated polymer chains and that it provides the most effective pathways for inter-site hopping processes.

No MeSH data available.


Related in: MedlinePlus