Comparison of the π-conjugated ring orientations in polyaniline and polypyrrole

Choi, Jaewu; Chipara, Mircea; Xu, Bin; Yang, Chunming; Doudin, B.; Dowben, Peter A.

doi:10.1016/s0009-2614(01)00469-9

Cited by 35 publications

(52 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both high resolution and angle-resolved photoemission studies were undertaken. The fi lms were studied by angle resolved and polarization dependent photoemission, as described in detail elsewhere [3,5,10,11], and were carried out at the Center for Advanced Microstructures and Devices synchrotron radiation facility using light dispersed by a 3 m toroidal grating monochromator. The high resolution ultraviolet photoemission spectroscopy (UPS) were undertaken using a helium lamp at hv = 21.2 eV (He I) and a Scienta 200 hemispherical electron analyzer with a combined resolution better than 10 meV [12].…”

Section: Methodsmentioning

confidence: 99%

“…As is typical with large organic molecules [3,5,11,28], the partial cross-section for photoemission varies according to the orientation of the light vector potential A and the symmetry of the initial state ψ i , assuming that the fi nal state wave function ψ f (for electrons collected along the surface normal) is fully symmetric. The evidence of strong light polarization effects suggests a preferential orientation of the polymer chains as has been observed in other polymer systems [3,5,11,28], including a number of spin coated conducting polymers fi lms like such as polyaniline [3], polypyrrole [3], poly(3,4-ethylenedioxythiophene)-polyethylglycol (PEDOT-PEG) [28] and poly[2methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) [5]. Unfortunately, due to the low symmetry of RR-P3HT combined with the large number of overlapping molecular orbitals that contribute to each photoemission feature, we cannot conclusively ascertain, from Figure 2, the specifi c preferential orientation adopted by RR-P3HT in our fi lms.…”

Section: Stability In Polymer Orientationmentioning

confidence: 99%

“…For conducting polymers, changes in the relative orientation of aromatic rings and/or overall backbone confi guration with temperature, are commonly observed [1][2][3][4]. Such structural changes lead to reduced π-π intermolecular interactions and/or create defects that can have a profound effect on conductivity and π-band localization in the highest occupied molecular orbitals.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Defect contributions to conductivity in poly(3‐hexylthiophene)?

Caruso

Feng

Losovyj

et al. 2006

Physica Status Solidi (b)

View full text Add to dashboard Cite

We fi nd evidence for a gradual change in the electronic properties of spin coated poly(3-hexylthiophene) thin fi lms with temperature. The conduction properties appears to be mediated by hopping conduction dominated by a low density of defects states within the highest occupied molecular orbital to lowest unoc cupied molecular orbital gap, not by a change in band gap. The photoemission and transport measure ments indicate a loss of charge mobility or carrier concentration occurs with decreasing temperature, while the molecular confi guration (through chain conjugation) also changes with temperature. The defects states identifi ed by photoemission (-1.7 eV) as well as others contributing to the transport properties are believed to be very heterogeneous along the polymer backbone.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Stability In Polymer Orientationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Defect contributions to conductivity in poly(3‐hexylthiophene)?

Caruso

Feng

Losovyj

et al. 2006

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

“…Changes in band gap with temperature are often observed with semiconducting polymers [1][2][3][4][5][6] and can be useful not only as optical temperature indicators but also for thermal recording. 7 Moreover, thermal control of the band gap allows for a continuous variation of electroluminence energies (wavelengths) for polymer light-emitting diodes.…”

Section: Introductionmentioning

confidence: 99%

Photohole Screening Effects in Polythiophenes with Pendant Groups

et al. 2005

View full text Add to dashboard Cite

We compare two mechanisms that dominate the temperature-dependent changes in electronic structure for poly(3-hexylthiophene-2,5 diyl) (P3HT). Structural changes in the relative orientation and configuration of the aromatic ring backbone are observed to occur over a wide range in temperature and affect the local final state screening in photoemission. There are also changes in conductivity and carrier concentration at lower temperatures leading to altered long-range intramolecular screening of photoholes and final state effects that affect excitation spectroscopies including photoemission. For polyethylenedioxythiophene (PEDOT), temperature-dependent changes in the structure and configuration of the polymer backbone are not as significant, although temperature-dependent final state effects are observed.

show abstract

“…The light polarization dependent angle-resolved photoemission experiments were carried out using synchrotron radiation, dispersed by a 3 m toroidal monochromator, at the Center for Advanced Microstructure and Devices (CAMD) in Baton Rouge, LA, as described elsewhere [33][34][35]. The measurements were performed in an ultra high vacuum (UHV) chamber employing a hemispherical electron energy analyzer with an angular acceptance of ±1°, as described elsewhere [35].…”

Section: Methodsmentioning

confidence: 99%