SZAB Kémiai Szakbizottság
elnök:  Erdőhelyi András

Anyagtudományi Munkabizottság
elnök:  Berkó András        titkár: Kokavecz János

Tisztelettel meghívjuk Önt és Munkatársait
a SZAB Anyagtudományi Munkabizottság 
2015 május 20.-án (szerda) 14:00 órakor kezdődő rendezvényére.
Helyszín: SZAB Székház I. em. Díszterem, Szeged, Somogyi u. 7.

Előadások

Dr. Attila J Mózer
„Charge generation, transport and recombination in di-chomophoric porphyrin-sensitised solar cells”
ARC Centre of Excellence for Electromaterials Science and Intelligent Polymer Research Institute, University of Wollongong, Australia

Dr. Shogo Mori
„Requirements to achieve more than 20% energy conversion efficiency for dye-sensitized solar cells”
Division of Chemistry and Materials, Faculty of Textile Science and Technology, 
Center for Energy and Environmental Science, Shinshu University

Az előadások időtartama 40 perc, amelyet 5-10 perc diszkusszió követ.

Vendéglátó intézmény:
SZTE TTIK Fizikai Kémiai és Anyagtudományi Tanszék / Dr. Janáky Csaba

Tisztelettel kérjük, hogy részvételével járuljon hozzá az ATMB eredményes munkájához, és szíveskedjék a Doktori Iskolák ösztöndíjasait az előadások meghallgatására bíztatni.

Szeged, 2015. május 11.

           Abstract
Charge generation, transport and recombination in di-chromophoric porphyrin-sensitised solar cells 
Attila J. Mozer 
ARC Centre of Excellence for Electromaterials Science and Intelligent Polymer Research Institute, University of Wollongong, Australia 

Multi-chromophoric porphyrin dyes are interesting for their application in dye-sensitised solar cells (DSSC), due to the benefits of extending the light harvesting range in a manner analogous to natural light harvesting in plants. The term 3-D light harvesting was coined to describe several covalently linked chromophores within a molecular sensitiser attached to the electron acceptor TiO2, contrasting the monolayer coverage of single chromophore / single dye arrangements of more conventional DSSC designs. 
This presentation will first describe porphyrin dimers developed for DSSCs focusing on light harvesting, charge photogeneration and collection efficiencies using a combination of steady state and transient photovoltage and photocurrent measurements. Using femtosecond transient absorption spectroscopy, charge injection efficiencies close 80% are measured in a porphyrin dimer sensitised solar cell, suggesting that both photoexcited porphyrin chromophores contribute to charge injection. Furthermore, increased electron lifetimes are discussed in terms of a steric blocking effect due to the bulkiness of the dimer sensitiser, preventing the approach of triiodide ions in the electrolyte to the dye/TiO2 surface. 
Secondly, three generations of di-chromophoric carbazole-substituted porphyrin dyes are developed with decreasing bandgap for photon absorption by the attached chromophores. The performance of these dyes is discussed in terms of increased light harvesting and decreased injection efficiencies, affected by the first reduction potential of the photoexcited chromophore relative to the TiO2 conduction band edge. Increased open circuit voltage (VOC), attributed to increased electron lifetime due to a steric blocking effect has been observed. A cascade hole transfer from the porphyrin core to the side chain chromophore was observed using transient absorption spectroscopy, which enhances the dye regeneration rate. The results suggest that developing multi-chromophoric dyes can lead to simultaneous increases in both the photocurrent and the photovoltage of dye-sensitized solar cells. 

Short Biography 
Attila J. Mozer is an Associate Professor at the University of Wollongong, Australia. He is the lead Chief Investigator of three Australian Research Council (ARC) grants focusing on dye-sensitised and polymer/fullerene bulk heterojunction solar cells. He is also a Chief Investigator / Project Leader of Characterisation within the ARC Centre of Excellence for Electromaterials Science (http://www.electromaterials.edu.au). He received an MBA with Distinction from the Sydney Business School in 2013, a PhD in Physical Chemistry from the Linz Institute for Organic Solar Cells, Austria (2004) and an MSc in Chemical Engineering from the Technical University of Budapest, Hungary (2002). He has authored 62 publications since his first publication in 2004 and has an h index of 28 with over >2000 total citations (Google scholar).
                      Abstract
Requirements to achieve more than 20%energy conversion efficiency for dye-sensitized solar cells
Shogo Mori
Division of Chemistry and Materials, Faculty of Textile Science and Technology, Center for Energy and Environmental Science, ShinshuUniversity 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan

Dye-sensitized solar cells consist of metal oxide semiconductor such as TiO2 and ZnO, organic dyes, and electrolytes. The reported highest energy conversion efficiency of dye-sensitized solar cells is 13%. In dye-sensitized solar cells, there are two interfaces to separate charges, and typically 0.2 eV and 0.4 eV are wasted at dye/semiconductor and dye/electrolyte interfaces, respectively. For charge injection, typically density of state in semiconductor and physical distance between dye and semiconductor have been considered as parameters influencing the injection. However, they cannot always explain experimental results. After injection, dye-cations are formed, and are ideally reduced by oxidized species of redox couple in electrolyte solutions. To reduce the dye cations by the species but not by the injected electrons, typically dyes are designed so that the difference between the dye’s HOMO level and electrolyte’s redox potential becomes more than 0.4 eV. However, the difference should be decreased to obtain higher open circuit voltage. In order to reduce the difference, we need to understand the factors influencing the reduction rate and their mechanisms. However, not all factors have been revealed yet. Here, possible factors controlling the charge transfer kinetics at both interfaces and possibility to achieve 20% efficiency are discussed.

Short Biography
Shogo Mori is an associate professor of Faculty of Textile Science and Technology, and Center for Energy and Environmental Scienceat Shinshu University in Japan, where he has been since 2005. His former family name is Nakade. He received a B.S. and a M.S. in Physics from University of Toledo, U.S.A., in 1996 and 1998, respectively. He receivedthe Ph.D. degree in EngineeringScience from Osaka University, Japan, in 2004. From 1999 to 2005, he was a research engineer at Nokia ResearchCenter at Tokyo in Japan, working for various materials and energy sources. His current research interests are interactions between photon and materials, and charge transport and transfer, especially at semiconductor/dye/electrolyte interface in dye-sensitized solar cells. He is the author of more than 60 papers and proceedings that have receivedover 4000 citations. He has two patents and seven patent pendings, and is co-author of a chapter of two books. http://www.researcherid.com/rid/B-3817-201