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Synthesis, structure, and opto-electronic properties of organic-based nanoscale heterojunctions.

Rezek B, Cermák J, Kromka A, Ledinský M, Hubík P, Mareš JJ, Purkrt A, Cimrová V, Fejfar A, Kočka J - Nanoscale Res Lett (2011)

Bottom Line: We show that employing and combining advanced scanning probe techniques can provide us significant insight into the correlation of these properties.These data are further correlated with local material composition detected using micro-Raman spectroscopy and with other electronic transport data.We demonstrate benefits of this multi-dimensional characterizations on (i) bulk heterojunction of fully organic composite films, indicating differences in blend quality and component segregation leading to local shunts of photovoltaic cell, and (ii) thin-film heterojunction of polypyrrole (PPy) electropolymerized on hydrogen-terminated diamond, indicating covalent bonding and transfer of charge carriers from PPy to diamond.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Physics ASCR, v,v,i,, Cukrovarnická 10, 16200 Prague 6, Czech Republic. rezek@fzu.cz.

ABSTRACT
Enormous research effort has been put into optimizing organic-based opto-electronic systems for efficient generation of free charge carriers. This optimization is mainly due to typically high dissociation energy (0.1-1 eV) and short diffusion length (10 nm) of excitons in organic materials. Inherently, interplay of microscopic structural, chemical, and opto-electronic properties plays crucial role. We show that employing and combining advanced scanning probe techniques can provide us significant insight into the correlation of these properties. By adjusting parameters of contact- and tapping-mode atomic force microscopy (AFM), we perform morphologic and mechanical characterizations (nanoshaving) of organic layers, measure their electrical conductivity by current-sensing AFM, and deduce work functions and surface photovoltage (SPV) effects by Kelvin force microscopy using high spatial resolution. These data are further correlated with local material composition detected using micro-Raman spectroscopy and with other electronic transport data. We demonstrate benefits of this multi-dimensional characterizations on (i) bulk heterojunction of fully organic composite films, indicating differences in blend quality and component segregation leading to local shunts of photovoltaic cell, and (ii) thin-film heterojunction of polypyrrole (PPy) electropolymerized on hydrogen-terminated diamond, indicating covalent bonding and transfer of charge carriers from PPy to diamond.

No MeSH data available.


Related in: MedlinePlus

Macroscopic and microscopic opto-electronic characteristics of the organic blends. (a, b) Macroscopically measured current-voltage characteristics of the blend films under illumination (white light, 80 mW) in the nitrogen atmosphere (0 h) and after exposure to ambient air for 2 and 6 h. The inset images in (a, b) show AFM topography images of the blend films (1 × 1 μm2, height scale 30 nm). (c, d) Cross sections of the KFM images (shown as insets, 1 × 1 μm2, potential scale 40 mV) under repeated on/off switching of illumination.
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Figure 3: Macroscopic and microscopic opto-electronic characteristics of the organic blends. (a, b) Macroscopically measured current-voltage characteristics of the blend films under illumination (white light, 80 mW) in the nitrogen atmosphere (0 h) and after exposure to ambient air for 2 and 6 h. The inset images in (a, b) show AFM topography images of the blend films (1 × 1 μm2, height scale 30 nm). (c, d) Cross sections of the KFM images (shown as insets, 1 × 1 μm2, potential scale 40 mV) under repeated on/off switching of illumination.

Mentions: Figure 3a, b shows macroscopic (with both top and bottom planar contacts) I(V) characteristics of the two blend films measured under white light illumination in the inert nitrogen atmosphere (0 h) and after exposure to ambient air. The PV device made of P3HT:[70]ThCBM blend exhibits initial power conversion efficiency(η) of 0.71% which is reduced, after exposure to ambient air for 6 h, to η = 0.37%. The reduction is due to the decrease in short-circuit current (Isc) from 4.02 to 2.08 mA/cm2 while open-circuit voltage (Voc) remains 0.55 V. Similar decreases in both power conversion efficiency and Isc were observed also on the device made of P3HT:[60]ThCBM blend (initial: η = 0.86%, Isc = 4.05 mA/cm2; after 6 h: η = 0.42%, Isc = 1.8 mA/cm2; Voc remains 0.48 V). In other words, both blends exhibit similar PV performance as well as its development in time.


Synthesis, structure, and opto-electronic properties of organic-based nanoscale heterojunctions.

Rezek B, Cermák J, Kromka A, Ledinský M, Hubík P, Mareš JJ, Purkrt A, Cimrová V, Fejfar A, Kočka J - Nanoscale Res Lett (2011)

Macroscopic and microscopic opto-electronic characteristics of the organic blends. (a, b) Macroscopically measured current-voltage characteristics of the blend films under illumination (white light, 80 mW) in the nitrogen atmosphere (0 h) and after exposure to ambient air for 2 and 6 h. The inset images in (a, b) show AFM topography images of the blend films (1 × 1 μm2, height scale 30 nm). (c, d) Cross sections of the KFM images (shown as insets, 1 × 1 μm2, potential scale 40 mV) under repeated on/off switching of illumination.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211298&req=5

Figure 3: Macroscopic and microscopic opto-electronic characteristics of the organic blends. (a, b) Macroscopically measured current-voltage characteristics of the blend films under illumination (white light, 80 mW) in the nitrogen atmosphere (0 h) and after exposure to ambient air for 2 and 6 h. The inset images in (a, b) show AFM topography images of the blend films (1 × 1 μm2, height scale 30 nm). (c, d) Cross sections of the KFM images (shown as insets, 1 × 1 μm2, potential scale 40 mV) under repeated on/off switching of illumination.
Mentions: Figure 3a, b shows macroscopic (with both top and bottom planar contacts) I(V) characteristics of the two blend films measured under white light illumination in the inert nitrogen atmosphere (0 h) and after exposure to ambient air. The PV device made of P3HT:[70]ThCBM blend exhibits initial power conversion efficiency(η) of 0.71% which is reduced, after exposure to ambient air for 6 h, to η = 0.37%. The reduction is due to the decrease in short-circuit current (Isc) from 4.02 to 2.08 mA/cm2 while open-circuit voltage (Voc) remains 0.55 V. Similar decreases in both power conversion efficiency and Isc were observed also on the device made of P3HT:[60]ThCBM blend (initial: η = 0.86%, Isc = 4.05 mA/cm2; after 6 h: η = 0.42%, Isc = 1.8 mA/cm2; Voc remains 0.48 V). In other words, both blends exhibit similar PV performance as well as its development in time.

Bottom Line: We show that employing and combining advanced scanning probe techniques can provide us significant insight into the correlation of these properties.These data are further correlated with local material composition detected using micro-Raman spectroscopy and with other electronic transport data.We demonstrate benefits of this multi-dimensional characterizations on (i) bulk heterojunction of fully organic composite films, indicating differences in blend quality and component segregation leading to local shunts of photovoltaic cell, and (ii) thin-film heterojunction of polypyrrole (PPy) electropolymerized on hydrogen-terminated diamond, indicating covalent bonding and transfer of charge carriers from PPy to diamond.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Physics ASCR, v,v,i,, Cukrovarnická 10, 16200 Prague 6, Czech Republic. rezek@fzu.cz.

ABSTRACT
Enormous research effort has been put into optimizing organic-based opto-electronic systems for efficient generation of free charge carriers. This optimization is mainly due to typically high dissociation energy (0.1-1 eV) and short diffusion length (10 nm) of excitons in organic materials. Inherently, interplay of microscopic structural, chemical, and opto-electronic properties plays crucial role. We show that employing and combining advanced scanning probe techniques can provide us significant insight into the correlation of these properties. By adjusting parameters of contact- and tapping-mode atomic force microscopy (AFM), we perform morphologic and mechanical characterizations (nanoshaving) of organic layers, measure their electrical conductivity by current-sensing AFM, and deduce work functions and surface photovoltage (SPV) effects by Kelvin force microscopy using high spatial resolution. These data are further correlated with local material composition detected using micro-Raman spectroscopy and with other electronic transport data. We demonstrate benefits of this multi-dimensional characterizations on (i) bulk heterojunction of fully organic composite films, indicating differences in blend quality and component segregation leading to local shunts of photovoltaic cell, and (ii) thin-film heterojunction of polypyrrole (PPy) electropolymerized on hydrogen-terminated diamond, indicating covalent bonding and transfer of charge carriers from PPy to diamond.

No MeSH data available.


Related in: MedlinePlus