Lackner, Gerhard:
Carbon nanotubes in organic solar cells
Duisburg, Essen, 2012
2012dissertation
Civil EngineeringFaculty of Engineering » Bauwissenschaften » Bauingenieurwesen » Materialwissenschaft
Title:
Carbon nanotubes in organic solar cells
Author:
Lackner, GerhardLSF
Place of publication:
Duisburg, Essen
Year of publication:
2012
Extent:
247, X S.
DuEPublico 1 ID:
Library shelfmark:
Note::
Duisburg, Essen, Univ., Diss., 2012

Abstract:

Organic solar cells have been lately attracting much attention due to Tang's technological breakthrough in organic solar cell construction [1]. In such devices efficiencies of over 8% have been achieved nowadays [2]. Due to such promising efficiencies, organic solar cells are being considered as a potential low-cost alternative to standard inorganic cells. It is expected that with the development of large-scale production methods the production cost benchmark of 1€ per Watt peak will be undercut. In addition, their competitiveness in the solar cell market is strongly enhanced by the use of flexible substrates, which offers a wide range of possible novel applications.<br> Such substrates can be coated with carbon nanotubes (CNT), which are being advocated as materials for interdigitated heterojunctions structure that would make organic solar cells to have high-performance. In view of this, this thesis reports a study that investigated the electrical roles of CNTs in organic solar cells in a novel inverted interdigitated structure using vertically aligned carbon nanotubes. The basis for use of CNT lies in the basic principle of energy conversion in solar cell devices, which involves the separation of photogenerated charges at an interface between electron donor and acceptor materials. In most cases, this imposes some constraints on the photoactive layer of the cells. Thus, to improve the active layer morphology and cell efficiency, anisotropic nanoparticles, the CNT can be incorporated to facilitate charge transport to the electrodes.<br> First prototypes of organic solar cells with this inverted interdigitated structure using a va-CNT array have been produced. These devices give the proof of the working principle of this solar cell structure. Other solar cell structures including a blend of donor-acceptor materials and randomly dispersed CNTs have been studied as well. Their performances were characterized and an increase of photocurrent was observed for these devices compared to devices without CNTs.<br> <br> This thesis is divided into 4 parts: firstly the chapters Introduction and Fundamentals deal with the fundamental functioning and characteristics of organic solar cells and the used materials, as well as the correlation between irradiation, internal charge transfer mechanisms and resulting efficiency. Secondly, the chapters Materials, Solution processed organic solar cells, and Carbon nanotube processing deal with the technological implementation of the pursued cell architectures including all steps of manufacturing. In the third part, the chapters Carbon nanotube solar cells and Vertically aligned carbon nanotube solar cells deal with the quality and properties of the produced dispersions, layers, semi-finished products and devices in detail. Finally, in the chapter Conclusions the results are discussed, conclusions drawn and an outlook given. Bibliography [1] C.W. TANG: Two-layer organic photovoltaic cell. In: Appl Phys Lett 48 (1986), S. 183-185 [2] Website. Available online at http://www.nrel.gov/ncpv/images/efficiency_chart.jpg; visited on November 11th 2011.