Limits...
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

Surface potential of PPy-diamond heterojunction as function of illumination and time. (a) Three-dimensional representation of surface potential map, and (b) temporal potential profiles that were obtained via KFM scanning across PPy-diamond and bare diamond surface (where PPy was removed) under repeated illumination switching. The positions of profiles are indicated by lines and arrows in the image.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211298&req=5

Figure 7: Surface potential of PPy-diamond heterojunction as function of illumination and time. (a) Three-dimensional representation of surface potential map, and (b) temporal potential profiles that were obtained via KFM scanning across PPy-diamond and bare diamond surface (where PPy was removed) under repeated illumination switching. The positions of profiles are indicated by lines and arrows in the image.

Mentions: To study optoelectronic properties at the PPy-diamond interface we first removed PPy from a small area (10 × 10 μm) using the AFM nanoshaving. Micro-Raman spectroscopy confirmed the removal of PPy [45]. This area and its surroundings were then studied by KFM in the dark and under the white light illumination. Similar to the experiments on advanced bulk heterojunctions, the KFM measurement was performed with one-scan direction disabled, and the illumination was repeatedly switched on and off (Figure 7a). Figure 7b shows temporal potential profiles that were obtained via KFM scanning across PPy-diamond and bare diamond surface (where PPy was removed) under repeated illumination switching. The positions of profiles are indicated by lines and arrows in the image. The changes of potential are relatively fast (<1 s, limited by KFM scan speed), reproducible, and well defined.


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)

Surface potential of PPy-diamond heterojunction as function of illumination and time. (a) Three-dimensional representation of surface potential map, and (b) temporal potential profiles that were obtained via KFM scanning across PPy-diamond and bare diamond surface (where PPy was removed) under repeated illumination switching. The positions of profiles are indicated by lines and arrows in the image.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Surface potential of PPy-diamond heterojunction as function of illumination and time. (a) Three-dimensional representation of surface potential map, and (b) temporal potential profiles that were obtained via KFM scanning across PPy-diamond and bare diamond surface (where PPy was removed) under repeated illumination switching. The positions of profiles are indicated by lines and arrows in the image.
Mentions: To study optoelectronic properties at the PPy-diamond interface we first removed PPy from a small area (10 × 10 μm) using the AFM nanoshaving. Micro-Raman spectroscopy confirmed the removal of PPy [45]. This area and its surroundings were then studied by KFM in the dark and under the white light illumination. Similar to the experiments on advanced bulk heterojunctions, the KFM measurement was performed with one-scan direction disabled, and the illumination was repeatedly switched on and off (Figure 7a). Figure 7b shows temporal potential profiles that were obtained via KFM scanning across PPy-diamond and bare diamond surface (where PPy was removed) under repeated illumination switching. The positions of profiles are indicated by lines and arrows in the image. The changes of potential are relatively fast (<1 s, limited by KFM scan speed), reproducible, and well defined.

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