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

Scratching of the PPy film by AFM tip with increasing contact force. Forces reaching 40 nN are strong enough to remove PPy molecules from diamond substrate.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Scratching of the PPy film by AFM tip with increasing contact force. Forces reaching 40 nN are strong enough to remove PPy molecules from diamond substrate.

Mentions: Thickness of the PPy film was 25 ± 5 nm based on the height histogram of tapping-mode AFM image after local nanoshaving of the PPy film in contact mode AFM [44]. Then, we applied contact-mode AFM with increasing contact force. At certain threshold contact force, the sharp tip starts to penetrate and remove the organic film. This transition is evidenced in Figure 5. The threshold force deduced in this manner was about 40 nN. This value is comparable to the values observed on a system consisting of diamond with covalently grafted DNA molecules [20,52]. This indicates that the PPy molecules also establish covalent bonds with H-terminated diamond.


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)

Scratching of the PPy film by AFM tip with increasing contact force. Forces reaching 40 nN are strong enough to remove PPy molecules from diamond substrate.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Scratching of the PPy film by AFM tip with increasing contact force. Forces reaching 40 nN are strong enough to remove PPy molecules from diamond substrate.
Mentions: Thickness of the PPy film was 25 ± 5 nm based on the height histogram of tapping-mode AFM image after local nanoshaving of the PPy film in contact mode AFM [44]. Then, we applied contact-mode AFM with increasing contact force. At certain threshold contact force, the sharp tip starts to penetrate and remove the organic film. This transition is evidenced in Figure 5. The threshold force deduced in this manner was about 40 nN. This value is comparable to the values observed on a system consisting of diamond with covalently grafted DNA molecules [20,52]. This indicates that the PPy molecules also establish covalent bonds with H-terminated diamond.

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