Book/Dissertation / PhD Thesis

FZJ-2017-04388

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Charakterisierung und Modifizierung von Kupferoxid- und Kupfersulfid-Nanopartikeln für Dünnschichtsolarzellen

Flohre, J. (Corresponding author)FZJ*

2017
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-241-2

Please use a persistent id in citations: http://hdl.handle.net/2128/14788

Abstract: The present thesis deals with the characterization and modification of semiconducting copper oxide and copper sulfide nanoparticles with respect to their use as active absorber material in an innovative solar cell concept. The well-established silicon based thin-film solar cell technology can be the basis for this concept and provides cost-effective production. Important requirements for the industrial relevance of the investigated materials, such as being earth abundant, environmentally friendly, as well as possessing both high absorption coeficients and suitable band gaps are fulfilled. The advantage of the concept is the decoupling of the nanoparticle absorber material optimization process from the module production. In this way, nanoparticles with high electronic quality can be prepared by high temperature processes or in chemically reactive environment while the subsequent module production is realized by economic processes at low temperature. Previous works have shown that proper annealing of the copper(II) oxide (CuO) nanoparticles leads to high quality material with respect to optoelectronic properties. In particular, in reducing atmosphere at high temperatures the phase transformation from CuO to copper(I) oxide (Cu$_{2}$O) is possible. In the current thesis it is shown that laser annealing in air leads to an improved micro-structure and a reduced defect density of the CuO nanoparticles. Furthermore, laser annealing in nitrogen atmosphere can transform the starting material into Cu$_{2}$O. Laser annealing has the advantage that selective parts of the sample can be modified. Thus, substrates that are not resistant to high temperature can be used and e.g. a post treatment of the particles in the solar cell is possible. Moreover, a CuO sample transformed into Cu$_{2}$O by annealing at 1000 $^{\circ}$C in nitrogen atmosphere is investigated by micro Raman and photoluminescence (PL) scanning measurements. It is shown, that the variation of structural properties is low while the variation of the electronic properties, in particular the defect structure, is very large. The characterization of the defect structure is realized by studying PL spectra, which were taken at a sample temperature of 93 K. Here, emission bands of different defect transitions, as well as excitonic transitions are detected and identified. The analysis of PL spectra taken at sample temperatures between 93K to 290K made it possible to calculate the excitonic band gap and the full width at half maximum of the excitonic emission. Stress in the crystal and the defect concentration are found to have an impact to these quantities. Therefore, the values are compared to those found in the literature of pure Cu$_{2}$O bulk material. The comparison reveals an higher defect concentration for the investigated Cu$_{2}$O [...]

Note: RWTH Aachen, Diss., 2016

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Contributing Institute(s):

1. Photovoltaik (IEK-5)

Research Program(s):

1. 121 - Solar cells of the next generation (POF3-121) (POF3-121)

Appears in the scientific report 2017

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