First-principles studies of some conducting polymers: PPP, PPy, PPV, PPyV, and PANI

Vaschetto, Mariana E.; Monkman, Andrew P.; Springborg, Michael

doi:10.1016/s0166-1280(98)00565-x

Cited by 50 publications

(32 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reported theoretical values, however, span a wide range from 1.46 eV (TBA) to 5.60 eV (HF) [5,11,20,[22][23][24][25][26][27]. Considering that the dihedral angle in our case is 28 , the 4.5 eV CB bandwidth reported here is consistent with the theoretical prediction of Champagne et al [27].…”

Section: H Y S I C a L R E V I E W L E T T E R Ssupporting

confidence: 91%

Resolving Band-Structure Evolution and Defect-Induced States of Single Conjugated Oligomers by Scanning Tunneling Microscopy and Tight-Binding Calculations

Wang

Lin

2011

Phys. Rev. Lett.

View full text Add to dashboard Cite

We study single conjugated polyphenylene oligomers consisting of 3n (2 n 12) phenyl units by means of cryogenic scanning tunneling microscopy and spectroscopy. The spatially resolved local densities of states reveal a progressive development of a continuous conduction band out of discrete molecular orbitals as the length of the oligomers increases. The experimental results are satisfactorily described by tight-binding calculations which gave a conduction band bandwidth of 4:5 AE 0:2 eV and a band gap of 3:1 AE 0:2 eV for an infinitely long polymer. We observed two types of defects, known as conformational torsional angle misfit and metasite kink. Tight-binding as well as density-functional theory model calculations confirm that both types of defects effectively destroy the delocalization. DOI: 10.1103/PhysRevLett.106.206803 PACS numbers: 73.22.Àf, 73.61.Ph, 68.37.Ef, 82.35.Cd One-dimensional (1D) conjugated polymers (CP) are both interesting scientifically and important for technological applications [1]. Theoretical descriptions of CP follow one of two routes: a delocalized band theory of solid-state physics or a localized molecular orbital approach of quantum chemistry [2][3][4]. In spite of their different perspectives, both approaches predict that the molecular orbitals of short oligomers develop progressively into a broad band in the long-length limit [5][6][7]. The bandlike features have been detected experimentally for short oligomers only [8,9]. The majority of attempts follow the so-called oligomer approach, in which the characteristics of short oligomers of increasing chain length are extrapolated to infinite polymers [10,11]. There are still significant discrepancies among different theories, as well as between theories and experimental results, and many fundamental properties of CP including bandwidth, band gap, and the influence of various structural defects, etc., are under debate [7].In particular, precise experimental determination of band structure, i.e., the energy-momentum dispersion, of CP or long oligomers has had limited successes largely due to the difficulty of growing high-purity single crystalline samples [12]. Above all, the existence of defects presents a severe challenge since defects in a 1D system can strongly alter its electronic structure [13]. Thus to be able to measure the electronic structure of a single CP whose molecular structure, including the details of defects, can be resolved simultaneously is highly desirable. Recently, Repp et al. demonstrated that scanning tunneling microscopy (STM) can provide an unprecedented view of the electronic structures of individual conjugated oligomers [14]. In this Letter we report the conductance band structures of single poly(para-phenylene) (PPP) oligomers determined by cryogenic (5 K) STM. We examine the energy-momentum dispersion of the PPP oligomers of up to 16 nm in length (36 phenyl units) and derive the conduction band bandwidth, energy gap, and the effective mass of charge carriers. Furthermore, we demonstrate and discuss how...

show abstract

Section: H Y S I C a L R E V I E W L E T T E R Ssupporting

confidence: 91%

Resolving Band-Structure Evolution and Defect-Induced States of Single Conjugated Oligomers by Scanning Tunneling Microscopy and Tight-Binding Calculations

Wang

Lin

2011

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

“…As indicated by the comparison of N2-PPP total p z and N-related p z projected DOS reported in Figure 6 c, the highest-lying valence bands are mainly composed by carbon π density, which amounts to saying that the heteroatom contributes little to define the hole carrier mobility in the valence band. 46 , 49 …”

Section: Resultsmentioning

confidence: 99%

Tunable Band Alignment with Unperturbed Carrier Mobility of On-Surface Synthesized Organic Semiconducting Wires

et al. 2016

View full text Add to dashboard Cite

The tunable properties of molecular materials place them among the favorites for a variety of future generation devices. In addition, to maintain the current trend of miniaturization of those devices, a departure from the present top-down production methods may soon be required and self-assembly appears among the most promising alternatives. On-surface synthesis unites the promises of molecular materials and of self-assembly, with the sturdiness of covalently bonded structures: an ideal scenario for future applications. Following this idea, we report the synthesis of functional extended nanowires by self-assembly. In particular, the products correspond to one-dimensional organic semiconductors. The uniaxial alignment provided by our substrate templates allows us to access with exquisite detail their electronic properties, including the full valence band dispersion, by combining local probes with spatial averaging techniques. We show how, by selectively doping the molecular precursors, the product’s energy level alignment can be tuned without compromising the charge carrier’s mobility.

show abstract

“…PPy/TiO 2 has two absorption peaks at 335 and 600 nm, respectively. The first peak corresponds to the n-p* transition of PPy, 14 Figure 6 shows the FTIR spectra of (a) TiO 2 nanopowder, (b) pure PPy, and (c) PPy/TiO 2 nanocomposite. Figure 6(b) indicates that characteristic absorption bands of PPy appear in the pure PPy, which are assigned as follows: the bands at 3400, 1450, and 1045 cm À1 have been attributed to N-H, C-N, and C-O-C stretching vibration, respectively, 16 whereas the peak at 1548 cm À1 represents the stretching vibration of C=C in pyrrole ring.…”

Section: Uv-vis Spectral Analysismentioning

confidence: 99%

Preparation and characterization of polypyrrole/TiO₂ nanocomposite and its photocatalytic activity under visible light irradiation

Chen

et al. 2009

J. Mater. Res.

View full text Add to dashboard Cite

A simple and convenient method for preparing visible light response photocatalyst polypyrrole/TiO 2 (PPy/TiO 2 ) nanocomposite was developed. The products were characterized by x-ray diffraction, transmission electron microscopy, atomic force microscopy, ultraviolet-visible, and Fourier transform infrared techniques. The results indicated that the nanohybrid was composed of anatase TiO 2 and PPy and exhibited an enhanced visible light-capturing ability. Average diameters of TiO 2 and PPy/TiO 2 were 18 and 35 nm, respectively. The photocatalytic activity of the nanocomposite was evaluated by the degradation of methyl orange under visible light irradiation. In the presence of PPy/TiO 2 nanocomposite, the degradation efficiency of methyl orange of 95.54% could be obtained under visible light irradiation within 120 min. The apparent rate constant was 2.19 Â 10 À2 , which was better than that Degussa P25 nano-TiO 2 . The sensitization mechanism of PPy/TiO 2 photocatalyst was discussed briefly.

show abstract

First-principles studies of some conducting polymers: PPP, PPy, PPV, PPyV, and PANI

Cited by 50 publications

References 45 publications

Resolving Band-Structure Evolution and Defect-Induced States of Single Conjugated Oligomers by Scanning Tunneling Microscopy and Tight-Binding Calculations

Resolving Band-Structure Evolution and Defect-Induced States of Single Conjugated Oligomers by Scanning Tunneling Microscopy and Tight-Binding Calculations

Tunable Band Alignment with Unperturbed Carrier Mobility of On-Surface Synthesized Organic Semiconducting Wires

Preparation and characterization of polypyrrole/TiO₂ nanocomposite and its photocatalytic activity under visible light irradiation

Contact Info

Product

Resources

About

First-principles studies of some conducting polymers: PPP, PPy, PPV, PPyV, and PANI

Cited by 50 publications

References 45 publications

Resolving Band-Structure Evolution and Defect-Induced States of Single Conjugated Oligomers by Scanning Tunneling Microscopy and Tight-Binding Calculations

Resolving Band-Structure Evolution and Defect-Induced States of Single Conjugated Oligomers by Scanning Tunneling Microscopy and Tight-Binding Calculations

Tunable Band Alignment with Unperturbed Carrier Mobility of On-Surface Synthesized Organic Semiconducting Wires

Preparation and characterization of polypyrrole/TiO2 nanocomposite and its photocatalytic activity under visible light irradiation

Contact Info

Product

Resources

About

Preparation and characterization of polypyrrole/TiO₂ nanocomposite and its photocatalytic activity under visible light irradiation