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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

Average surface potential obtained by KFM on PPy-diamond, H-diamond, and diamond after PPy removal. The potential values are referenced to the grounded Au contact pad.
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Figure 6: Average surface potential obtained by KFM on PPy-diamond, H-diamond, and diamond after PPy removal. The potential values are referenced to the grounded Au contact pad.

Mentions: Surface potential measured by KFM on the place where the PPy film had been deposited and removed (Figure 6) is significantly lower (by about 0.1 V) than the potential on pristine H-terminated diamond surface. This change is similar to reports on DNA-diamond interfaces [53] and supports the assertion of PPy molecules being linked to diamond surface covalently while removing the H termination. We also observed that the surface conductivity disappeared after the synthesis and the removal of the PPy molecules from diamond surface, which is most likely caused by the missing H termination.


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)

Average surface potential obtained by KFM on PPy-diamond, H-diamond, and diamond after PPy removal. The potential values are referenced to the grounded Au contact pad.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Average surface potential obtained by KFM on PPy-diamond, H-diamond, and diamond after PPy removal. The potential values are referenced to the grounded Au contact pad.
Mentions: Surface potential measured by KFM on the place where the PPy film had been deposited and removed (Figure 6) is significantly lower (by about 0.1 V) than the potential on pristine H-terminated diamond surface. This change is similar to reports on DNA-diamond interfaces [53] and supports the assertion of PPy molecules being linked to diamond surface covalently while removing the H termination. We also observed that the surface conductivity disappeared after the synthesis and the removal of the PPy molecules from diamond surface, which is most likely caused by the missing H termination.

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