Kadiatou Thérèse Dembélé

Kadiatou Therese Dembele

Tel.: +1 (514) 228-6971
Fax: +1 (450) 929-8102

Conventional solar cells have a relatively high-energy efficiency, but are still expensive because of the production cost. DSSCs are considered as third generation solar cells and have a low cost of production yet their energy conversion efficiency is still low. 
Carbon nanotubes (CNTs) are considered remarkable materials owing to their unique structural and mechanical properties such as high electrochemical stability, low resistivity, and high surface-to-volume ratio. CNTs have been used as a support for dispersions of functional materials in order to give these materials additional functionalities, such as structure, surface area, activity and conductivity. 

CNTs and titanium dioxide (TiO2) composite materials have attracted attention in the literature in relation to the treatment of contaminated water and air by heterogeneous photo-catalysis, hydrogen evolution, CO2 photo-reduction. They also have excellent properties to be used in dye sensitised solar cells and sensor devices. 

In this project and in collaboration with Professor Enrico Traversa and Silvia Licoccia (Tor Vergata University of Rome) group, we will study the best conditions to fabricate and use CNTs/TiO2 in DSSCs to increase their energy conversion efficiency. These composite materials have been fabricated by a range of different methods, including: mechanical mixing of TiO2 and CNTs, sol–gel synthesis of TiO2 in the presence of CNTs, electro-spinning methods and, electrophoretic deposition and chemical vapour deposition. The uniformity of the oxide coating and the physical properties of the composite materials vary according to the preparation method. 

In this work we will characterize the optimal conditions (methods of fabrication, concentration and ratio) to improve DSSCs solar conversion efficiency by using CNTs/TiO2 composites.
We also work on carbon nanostructures for Dye sensitized solar cell.
The research activities are mainly based on the use of the composites MWCNTs-TiO2 and Graphene-TiO2 based photoanodes. We have shown (reference 142 on our website) that in addition to the functional properties improvement, the incorporation of CNTs could enhance the time stability of theses parameters.
Graphene and CNTs improve the charge transport through the photoanode, which increase the current density in the device. However the presence of these carbon materials decreases the open circuit voltage due to their energy band structure, but the increasing of current largely compensate this decreasing, which leads to the increasing of the power conversion efficiency.
To efficiently use the excellent properties of Carbon nanostructures in DSSCs there is a need to choose an optimal percentage, because very low loading could not have any significant effect and high loading could affect negatively the cells characteristics. The second effect could be due to the reducing of the electron life times, light harvesting competition between the dye and the carbon materials.
New Collaboration for this project: CNR-IDASC SENSOR Lab affiliated to the University of Brescia, Italy.

Background/ Educations:

  • DEUG (Diplôme d’études universitaires générales) in Mathematics and Physics in the Faculty of Science and Technology – July 2003, Bamako (Mali).
  • Degree in Industrial Engineering, Option: Energy in the National School of Engineers – July 2006, Bamako (Mali).
  • M.Sc. in Energy and Materials Sciences, INRS-EMT – September 2011, Quebec (Canada)

NFL publications

D. Benetti, K. T. Dembele, J. Benavides, H. Zhao, S. Cloutier, I. Concina, A. Vomiero, and F. Rosei. Functionalized multi-wall carbon nanotubes/TiO 2 composites as efficient photoanodes for dye sensitized solar cells. Journal of Materials Chemistry C, 4, 3555 (2016). (PDF).
K. T. Dembele, G. S. Selopal, R. Milan, C. Trudeau, D. Benetti, A. Soudi, M. M. Natile, G. Sbervglieri, S. Cloutier, I. Concina, F. Rosei, and A. Vomiero. Graphene below the percolation threshold in TiO2 for dye-sensitised solar cells. Journal of Materials Chemistry A, 3, 2580 (2015). (PDF).
K. T. Dembele, G. S. Selopal, C. Soldano, R. Nechache, J. C. Rimada, I. Concina, G. Sberveglieri, F. Rosei, and A. Vomiero. Hybrid Carbon Nanotubes−TiO2 Photoanodes for High Efficiency Dye-Sensitized Solar Cells. The Journal of Physical Chemistry C, 117, 14510–14517 (2013). (PDF).
K. T. Dembele, R. Nechache, L. Nikolova, A. Vomiero, C. Santato, S. Licoccia, and F. Rosei. Effect of multi-walled carbon nanotubes on the stability of dye sensitized solar cells. Journal Of Power Sources, 233, 93–97 (2013). (PDF).