dc transport studies of poly(benzimidazobenzophenanthroline) a ladder-type polymer

Narayan, K. S.; Alagiriswamy, A. A.; Spry, R. J.

doi:10.1103/physrevb.59.10054

Cited by 13 publications

(13 citation statements)

References 19 publications

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“…The large improvement upon annealing is illustrated by the values of µ FET for PerPBO before and after annealing (Table 5). 30,54 Supporting Information Figure S7 shows the SEM images of PerPBO copolymer before and after annealing at 160 °C for 1 h, clearly showing differences in morphology upon annealing. Annealing can provide the polymer chains enough energy to access better conformational arrangement and sufficient time to have optimized alignment of the polymer chain within the microdomain itself and in the process decreasing the trap-state density.…”

Section: Resultsmentioning

confidence: 99%

n-Type Field Effect Transistors Based on Rigid Rod and Liquid Crystalline Alternating Copoly(benzobisoxazole) Imides Containing Perylene and/or Naphthalene

et al. 2010

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The synthesis, characterization, and device studies of poly(benzobisoxazole imide)s containing perylene or naphthalene units in an alternating fashion with the oxazole unit are described. Photoinduced energy transfer and charge separation were studied in methanesulfonic acid (MSA) solution via absorption, excitation, and steady-state fluorescence studies. Excitation of the bisoxazole moiety resulted in enhanced emission from the perylene bisimide unit as a result of FRET (Förster resonance energy transfer). The influence of the imide substitution into the linear chain of poly(benzobisoxazole) (PBO) on its solid-state packing was examined by wide-angle X-ray diffraction (WXRD) analysis. Bottom contact field effect transistors (FET) based on thermally annealed polymer films were fabricated and studied. The polymers showed n-type charge transport and current modulation with an on/off ratio greater than 10(2). It was observed that the FETs consisting of the random copolymer of bisoxazole containing both perylene as well as naphthalene bisimide units had higher performance parameters such as better mobility (μ(e)) and I(on)/I(off) ratio compared to those of the pristine systems.

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Section: Resultsmentioning

confidence: 99%

n-Type Field Effect Transistors Based on Rigid Rod and Liquid Crystalline Alternating Copoly(benzobisoxazole) Imides Containing Perylene and/or Naphthalene

et al. 2010

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“…Since 1960, a number of double-stranded ladder polymers have been synthesized that exhibits excellent stability in both air and nitrogen . The study of the electronic and optical properties of this stable polymer was reported in the eighties when BBL films were doped by chemical/electrochemical means as n-type and p-type materials. − The doped polymers exhibit high conductivities (∼2 S/cm) based on electron-donor strength (p-type), , which is attributed to the backbone planarity of the polymer. It is noteworthy that the electron mobility of BBL matches the hole mobility of P3HT .…”

Section: Introductionmentioning

confidence: 99%

Electronic Structures and Optical Absorption of N-Type Conducting Polymers at Different Doping Levels

et al. 2019

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Theoretical understanding of the electronic structure and optical transitions in n-doped conducting polymers is still controversial for polaronic and bipolaronic states and is completely missing for the case of a high doping level. In the present paper, the electronic structure and optical properties of the archetypical n-doped conducting polymer, doublestranded benzimidazo-benzophenanthroline ladder (BBL) are studied using the density functional theory (DFT) and time-dependent (TD) DFT method. We nd that a polaronic state in the BBL chain is a spin-resolved doublet where the spin-degeneracy is lifted. The ground state of two electrons corresponds to a triplet polaron pair, which is in stark contrast to a commonly accepted picture where two electrons are postulated to form a spinless bipolaron. The total spin gradually increases until the reduction level reaches c red = 100% (i.e. one electron per monomer unit). With further increase of the reduction level, the total spin decreases until it becomes 0 for the reduction level c red = 200%. The calculated results reproduce the experimentally observed spin signal without any phenomenological parameters. A detailed analysis of the evolution of the electronic structure of BBL and its absorption spectra with increase in reduction level are presented. The calculated UV-vis-NIR spectra are compared with the available experimental results. The electronic structure and optical absorption for dierent reduction levels presented here are generic to a wide class of conducting polymers, which is illustrated by the corresponding calculations for another archetypical conducting polymer, poly(3,4-ethylenedioxythiophene) (best known as PEDOT).

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“…An analysis of the defect dominated kinetics and polarization-dependent transient studies can resolve this apparent contradiction of the steady-state I ph results with the xerographic measurements. The effects of macroscopic factors on the dc conductivity (σ dc ) is sizable due to the barriers involved in the electronic transport between the fibrils and the inhomogeneous extrinsic impurity distribution which are more obvious from anisotropy of nearly four orders as observed in σ dc measurements [16]. Hence, the microscopic orientation observed in the fibers consisting of nearly-aligned polymer chains along with the PDIC results is a measure of the local anisotropy, distinguishing it from the larger length scale processes.…”

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confidence: 99%

“…16 Hence, the microscopic orientation observed in the fibers consisting of nearly aligned polymer chains along with the PDIC results are a measure of the local anisotropy, distinguishing it from the larger length scale processes. The sizable density of electronic defects in the system leading to trap limiting processes prevails over the photoinduced charge carrier generating rates and can mask the polarization-dependent initial charge generating features.…”

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Polarization-dependent discharge in fibers of a semiconducting ladder-type polymer

Kumar

Narayan

2001

Applied Physics Letters

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We report results on polarization-dependent photoinduced discharge in oriented fibers and films of ladder-type, electron-transporting polymer poly (benzimidazobenzophenanthroline), BBL. The photocarrier generation efficiency (φ) in the fiber which is indicated by the rate of discharge, is found to be distinctly higher for light polarized parallel to the fiber axis (P ) as compared to the radially perpendicular direction (P ⊥ ). Similar results, with φ anisotropy ∼ 10 are obtained for oriented films. These observations are different from previously obtained results on polyparaphenylenevinylene (PPV). The results are compared with the polarization-dependent steady-state photoconductivity measurements. We interpret these results on the basis of molecular and macroscopic features of the material.

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dc transport studies of poly(benzimidazobenzophenanthroline) a ladder-type polymer

Cited by 13 publications

References 19 publications

n-Type Field Effect Transistors Based on Rigid Rod and Liquid Crystalline Alternating Copoly(benzobisoxazole) Imides Containing Perylene and/or Naphthalene

n-Type Field Effect Transistors Based on Rigid Rod and Liquid Crystalline Alternating Copoly(benzobisoxazole) Imides Containing Perylene and/or Naphthalene

Electronic Structures and Optical Absorption of N-Type Conducting Polymers at Different Doping Levels

Polarization-dependent discharge in fibers of a semiconducting ladder-type polymer

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