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13.10.2017 - 12:00

6th OCL-TP Workshop

On 30-31th October, the 6th International Workshop between the "Optical Communication Lab" and the Department "Technological Physics" took place under framework of long-term cooperation agreement between the Israel Institute of Technology and the University of Kassel.

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28.02.2016 - 16:54

Q.com article in the „Physik in unserer Zeit“

A recent open-access article by research partners from the BMBF Q.com Research Network project entitled "Sichere Kommunikation per Quantenrepeater" is published in "Physik in unserer Zeit", which reports on the current state and the main challenges in this field.

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12.12.2015 - 12:00

3rd OCL-TP Workshop

On 10-11th December, the 3rd International Workshop between the "Optical Communication Lab" and the Department "Technological Physics" took place under framework of long-term cooperation agreement between the Israel Institute of Technology and the University of Kassel.

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INA - Technological Physics > Research > Nano Diamond > Projects Diamond Electrodes

Dye-Sensitized Nanostructured Diamond Electrodes for Solar Energy Conversion

Different strategies are currently being followed in order to develop technologies to capture sun light and utilize it for light-driven interactions leading to the generation of photocurrent or to the formation of pure fuels like hydrogen or methanol. The development of light-energy conversion systems, such as photoelectrochemical cells, requires careful selection and detailed investigation of electrode materials, of catalysts (e.g. required for the splitting of water into hydrogen and oxygen) and photosensitizers (i.e. dyes).

The general objective of this project is to prepare dye-sensitized diamond-based electrodes for solar energy conversion in photoelectrochemical cells. The combination of phthalocyanine molecules as dyes and nanostructured boron doped diamond (BDD) electrodes should provide, after design and fine-tuning of the individual energy levels for fast carrier transfer, a generation of photocurrent with optimized quantum efficiency of the color dye layer. Diamond is a promising candidate for such applications due to its outstanding properties, including metallic conductivity upon doping with boron, high chemical stability working in contact with liquid phases, even under extreme pH conditions, a large electrochemical potential window superior to those of the common electrode materials, low background currents, etc.

BDD films will be prepared by hot filament or microwave plasma chemical vapor deposition and their electrochemical performance will be optimized. Furthermore, diamond surfaces can be modified by plasma- or photo-chemical processes in order to achieve surface terminations beneficial for the functionalization with dye molecules. The phthalocyanines, compounds akin to chlorophyll which have already shown promising effects in solar photovoltaic cells, will be attached on the BDD surface as light harvesters and electron donors. In order to enhance the efficiency, the BDD will be nanostructured for increasing the effective area for the photosensitive layer and the absorbance per unit area, respectively. The surface modifications of BDD will be optimized providing desired H-, O- NH2- or F-terminations for anchoring of the dye molecules and appropriate band bending. Novel phthalocyanine molecules with different metal ions, side chains and, if required, additional ligands will be synthesized guided by quantum chemical calculations. Of crucial importance will be their pertinent orbital energies (HOMO and LUMO), their absorption maxima, stability and solubility. These phthalocyanine molecules will be grafted on differently modified and nanostructured BDD under controlled conditions providing stable binding and desired orientation on the surface.

Finally, the photoelectrochemical measurements of the open circuit potential and photocurrent at various biasing potentials, light sources with different spectra, electrolytes with different redox mediators and counter electrodes of different materials, i.e. with different surface potentials, will complete the experimental data collection, thus allowing a thorough characterization of the photovoltaic cells. As a result of this project it is expected to achieve photocurrent generation with reasonable efficiency of light conversion with the perspective of realizing photovoltaic cells in a following development project.

Projekt Partners

  • Prof. Ulrich Siemeling, Dept. of Metalorganic Chemistry, University of Kassel, Germany
  • Dr. Alberto Pasquarelli, Institute of Electron Devices and Circuits, University of Ulm, Germany
  • Prof. Michael Kopnarski, Dr. Dr.-Ing. Rolf Merz, Institut für Oberflächen- und Schichtanalytik (IFOS), Kaiserslautern, Germany
  • Dr. Miklos Veres, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary

Selected publications

  • S. Pehlivanova, Ch. Petkov, C. Popov, P. Petkov, V. Boev, T. Petkova, Nanostructured diamond electrodes for energy conversion applications, In: “Nanoscience Advances in CBRN Agent Detection, Information and Energy Security”, P. Petkov, D. Tsiulyanu, W. Kulisch and C. Popov (Eds.), NATO Science for Peace and Security Series - A: Chemistry and Biology, Springer, Dordrecht, Netherlands, 2015 (ISBN 978-94-017-9696-5) pp. 479-486.

Picture gallery

Top-view SEM micrograph of NCD film
Fig. 1: Top-view SEM micrograph of NCD film
AFM image of NCD film
Fig. 2: AFM image of NCD film
Structure of the manganese(III) phthalocyaninato complex (R = n-C8H17), one of the dyes used in the current work
Fig. 3: Structure of the manganese(III) phthalocyaninato complex (R = n-C8H17), one of the dyes used in the current work
Surface composition of as-grown and plasma modified NCD surfaces without and with Mn-Pc as determined by XPS
Fig. 4: Surface composition of as-grown and plasma modified NCD surfaces without and with Mn-Pc as determined by XPS
Surface composition of O2 plasma modified NCD surfaces after grafting of Mn-Pc, Cu-Pc and Ti-Pc  as determined by XPS
Fig. 5: Surface composition of O2 plasma modified NCD surfaces after grafting of Mn-Pc, Cu-Pc and Ti-Pc as determined by XPS
Raman spectra of NCD (785 nm excitation wavelength) after oxygen plasma modification and grafting of Mn-Pc. The spectrum of Mn-Pc is also shown as reference.
Fig. 6: Raman spectra of NCD (785 nm excitation wavelength) after oxygen plasma modification and grafting of Mn-Pc. The spectrum of Mn-Pc is also shown as reference.
Orientation of Mn-Pc molecules on the O-terminated NCD surface as suggested by NEXAFS spectroscopy results
Fig. 7: Orientation of Mn-Pc molecules on the O-terminated NCD surface as suggested by NEXAFS spectroscopy results
Photocurrent and photopotential of NH2-terminated NCD electrode grafted with Mn-Pc upon illumination with 770 nm
Fig. 8: Photocurrent and photopotential of NH2-terminated NCD electrode grafted with Mn-Pc upon illumination with 770 nm

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