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

Rezek, Bohuslav and Cermak, Jan and Kromka, Alexander and Ledinsky, Martin and Hubik, Pavel and Mares, Jiri and Purkrt, Adam and Cimrova, Vaera and Fejfar, Antonin and Koacka, Jan (2011) Synthesis, structure, and opto-electronic properties of organic-based nanoscale heterojunctions. Nanoscale Research Letters, 6 (1). pp. 1-12. ISSN 10.1186/1556-276X-6-238

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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.

Item Type:Article
Subjects:Material Science > Functional and hybrid materials
Physical Science > Nanoelectronics
Material Science > Nanostructured materials
ID Code:10937
Deposited By:JNCASR
Deposited On:30 Aug 2011 11:32
Last Modified:30 Aug 2011 11:32

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