Influence of disorder on the field-modulated spectra of polydiacetylene films

Horvath, A.; Weiser, G.; Baker, Gregory L.; Etemad, S.

doi:10.1103/physrevb.51.2751

Cited by 49 publications

(46 citation statements)

References 25 publications

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“…This is also true for the electroabsorption spectrum which is very similar to that of a spin cast 4BCMU film. 24 The exciton and its vibrational satellites which due to inhomogeneous broadening are barely resolved still respond with a common quadratic Stark shift. The agreement of derivative and electroabsorption spectrum improves further below 2.2eV if one accounts for the loss of strength of the allowed transition.…”

Section: Thermal and Disorder-induced Broadeningmentioning

confidence: 99%

Franz-Keldysh effect of band states in polydiacetylene

1997

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Electroabsorption spectra of polydiacetylene single crystals with well ordered chains show 0.5eV above the excitonic absorption edge a strong signal from states which contribute little to absorption. While the strongly absorbing excitons respond to an external field by a quadratic Stark effect this particular signal is attributed to the FranzKeldysh effect, the response of a free carrier band. The extended band states are very sensitive to an external field but also to disorder which destroys the coherence of free motion. Experimental spectra of the Franz-Keldysh effect of well ordered chains will be compared with those of semiconductors and with model calculations for a one-and a three-dimensional electron gas. These calculations reveal that one-dimensional bands respond much more sensitive to electric fields than three-dimensional band states. The comparison of the spectral lineshapes points to a forbidden parity state very close to the band edge which enhances some spectral features. The Franz-Keldysh effect deteriorates rapidly with disorder which is interpreted as due to localization of bandstates by disorder. The Stark effect of such near degenerate states localized by boundary conditions can lead to similar spectra as the Franz-Keldysh effect.

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Section: Thermal and Disorder-induced Broadeningmentioning

confidence: 99%

Franz-Keldysh effect of band states in polydiacetylene

1997

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“…Under a strong applied electric field, a significant Stark shift would manifest in the spectra near the absorption edge, as seen previously in electroabsorption measurements. [42][43][44][45][46][47][48][49][50][51] We do observe some additional structure in the bleached absorption above the band edge in Fig. 4.…”

Section: Resultsmentioning

confidence: 72%

Electron and hole polaron accumulation in low-bandgap ambipolar donor-acceptor polymer transistors imaged by infrared microscopy

et al. 2014

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A resurgence in the use of the donor-acceptor (DA) approach in synthesizing conjugated polymers has resulted in a family of high-mobility ambipolar systems with exceptionally narrow energy bandgaps below 1 eV. The ability to transport both electrons and holes is critical for device applications such as organic light-emitting diodes (OLEDs) and transistors (OLETs). Infrared spectroscopy offers direct access to the low-energy excitations associated with injected charge carriers. Here we use a diffraction-limited IR microscope to probe the spectroscopic signatures of electron and hole injection in the conduction channel of an organic field-effect transistor (OFET) based on an ambipolar DA polymer polydiketopyrrolopyrrole-benzobisthiadiazole (PDPPBBT). We observe distinct polaronic absorptions for both electrons and holes, and spatially map the carrier distribution from the source to drain electrodes for both unipolar and ambipolar biasing regimes. For ambipolar device configurations, we observe the spatial evolution of hole-induced to electron-induced polaron absorptions throughout the transport path. Our work provides a platform for combined transport and infrared studies of organic semiconductors on micron length scales relevant to functional devices.

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“…Fig. 7 displays data of a 4BCMU film [17] which are very similar to those of other conjugated polymer films [18]. The absorption spectra show only hints to a vibronic progression and little narrowing is observed even if stretching results in pronounced optical anisotropy [19].…”

Section: Article In Pressmentioning

confidence: 60%

“…Taylor expansion of Da and integrating for polarization of light E ? F over a random distribution of dipoles leads to a second derivative lineshape and a quadratic field effect [17]:…”

Section: Article In Pressmentioning

confidence: 99%

Comparative electroabsorption studies of organic and inorganic solids

Weiser

2004

Journal of Luminescence

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Influence of disorder on the field-modulated spectra of polydiacetylene films

Cited by 49 publications

References 25 publications

Franz-Keldysh effect of band states in polydiacetylene

Franz-Keldysh effect of band states in polydiacetylene

Electron and hole polaron accumulation in low-bandgap ambipolar donor-acceptor polymer transistors imaged by infrared microscopy

Comparative electroabsorption studies of organic and inorganic solids

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