Unexpected orientational effects in spin-cast, sub-micron layers of poly(alkylthiophene)s: A diffraction study with synchrotron radiation

Fell, H.J.; Samuelsen, Emil J.; Als‐Nielsen, J.; Grübel, G.; Mårdalen, Jostein

doi:10.1016/0038-1098(95)00167-0

Cited by 42 publications

(30 citation statements)

References 6 publications

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“…In our experiment, two factors may contribute to low degree of order: i) entangled polymer chains, such as present in amorphous domains and ii) no distinct polymer-chain orientation within the resolution limit of our technique (≈50 nm). However, this orientation is not favored for thin P3HT layers spin-coated on a substrate [39,46] and furthermore, the overall photoelectron intensity of such an orientation should be very low, which does not agree with our findings (cf. In both cases, (i) and (ii), the low degree of order will affect energetic and dynamics properties of the corresponding region on the polymer film.…”

Section: Polymer Filmscontrasting

confidence: 99%

Imaging Nanoscale Morphology of Semiconducting Polymer Films with Photoemission Electron Microscopy

et al. 2017

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Photoemission electron microscopy in combination with polarized laser light is presented as a tool permitting direct imaging of polymer-chain orientation and local degree of order in semicrystalline samples of semiconducting polymers, a promising class of materials for future electronics. The key advantages of this imaging tool are its nondestructive and fast measurements, straightforward data analysis, the low complexity of sample preparation, and the possibility of performing measurements on a broad variety of technologically relevant substrates. The high spatial resolution of the microscope provides insights into the nanoscale morphology, which is relevant for the material's performance in electronic devices.

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Section: Polymer Filmscontrasting

confidence: 99%

Imaging Nanoscale Morphology of Semiconducting Polymer Films with Photoemission Electron Microscopy

et al. 2017

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“…In the case of first order diffraction, this peak reveals the presence of a well-developed structure directed perpendicular to the quartz substrate with an interplanar distance equal to 17.0 Å. This distance most likely corresponds to the spacing between P3HT chains along the hexyl side chains, as reported in several earlier works 23,[25][26][27] and shown schematically in Fig. 5͑b͒.…”

Section: E Determination Of the Molecular Organizationsupporting

confidence: 72%

“…[23][24][25][26][27] The organization of polyalkylthiophene backbones has been observed to strongly affect charge transport 22,24 and may also influence the extent of exciton diffusion. In this work, the photophysical and morphological properties of a combination of the visible-light absorbing electron-accepting porphyrin derivative meso-tetrakis ͑n-methyl-4-pyridyl͒ porphyrin tetrachloride ͑H 2 TMPyP͒ and regioregular poly͑3-hexylthiophene͒ ͑P3HT͒ are presented.…”

Section: ͑2͒mentioning

confidence: 99%

An experimental study on the molecular organization and exciton diffusion in a bilayer of a porphyrin and poly(3-hexylthiophene)

Huijser

Savenije

Shalav

et al. 2008

Journal of Applied Physics

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The exciton root-mean-square displacement ͑⌳ D ͒ in regioregular poly͑3-hexylthiophene͒ ͑P3HT͒ deposited onto meso-tetrakis ͑n-methyl-4-pyridyl͒ porphyrin tetrachloride ͑H 2 TMPyP͒ has been determined from the photovoltaic response of a device based on these materials in a bilayer configuration. Excitons formed on illumination that reach the interface between H 2 TMPyP and P3HT can undergo interfacial charge separation by electron injection into the H 2 TMPyP and hole injection into the P3HT. The incident photon to current efficiency ͑IPCE͒ exceeds 20% over a broad wavelength regime. The theoretical analysis of the IPCE values gives a value for ⌳ D in H 2 TMPyP that amounts to 14 nm, while for P3HT a value of 18 nm is obtained. The latter value exceeds literature values reported for P3HT by almost a factor of 3. X-ray diffraction analysis shows that in the studied bilayer the P3HT backbones are aligned parallel to the interface with H 2 TMPyP. In contrast, in the case of P3HT deposited onto TiO 2 , for which ⌳ D has been reported to equal only 7 nm, hardly any organization of the P3HT backbones is observed. The excitonic coupling between P3HT backbones deposited onto H 2 TMPyP is as high as 125 cm −1 , a factor of 3 larger than the excitonic coupling between the disordered P3HT backbones that amounts to 47 cm −1 . The difference illustrates the importance of controlling the molecular organization for the realization of efficient energy transfer in organic optoelectronics.

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“…Similar effects have previously been reported for differences in stereoregularity, spin/drop casting, and choice of solvent. [30][31][32] The polymers spin cast from chloroform tend to have a bimodal orientation distribution with a significant fraction of microcrystalline grains oriented with the a axis in plane. 31 This is also evidenced by rocking scans of the 100 reflection ͓Fig.…”

Section: Structural Characterizationmentioning

confidence: 99%

Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

et al. 2006

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Interchain interactions have a profound effect on the optical as well as charge transport properties of conjugated polymer thin films. In contrast to oligomeric model systems in solution-deposited polymer thin films the study of such effects is complicated by the complex microstructure. We present here a detailed study of interchain interaction effects on both charged polarons as well as neutral excitons in highly crystalline, high-mobility poly-3-hexylthiophene ͑P3HT͒ as a function of molecular weight. We find experimental evidence for reduced exciton bandwidth and increased polaron delocalization with increasing conjugation length and crystalline quality. From comparative studies of field-effect transistor characteristics, film morphology, and optical properties our study provides a microscopic understanding of the factors which limit the charge transport in P3HT to field-effect mobilities around 0.1 cm 2 / V s, and which will need to be addressed to improve mobility further.

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Unexpected orientational effects in spin-cast, sub-micron layers of poly(alkylthiophene)s: A diffraction study with synchrotron radiation

Cited by 42 publications

References 6 publications

Imaging Nanoscale Morphology of Semiconducting Polymer Films with Photoemission Electron Microscopy

Imaging Nanoscale Morphology of Semiconducting Polymer Films with Photoemission Electron Microscopy

An experimental study on the molecular organization and exciton diffusion in a bilayer of a porphyrin and poly(3-hexylthiophene)

Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

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