Studio del ruolo dei metalli nella progettazione e utilizzo di nuovi materiali per celle solari organiche di terza generazione

The project aims at the theoretical design, synthesis and photophysical characterization of new organic and organometallic systems for applications in Dye Sensitized Solar Cells (DSSCs) and Bulk Heterojunction solar cells (BHJ).

1. 
   DSSCs:
   the research plans to investigate the following new molecular systems:
   
   
   
   
   • metal porphyrins symmetrically and asymmetrically substituted in the
     meso
     positions with phenyl,
     ortho
     -fused polycyclic heteroaromatic/thiofene containing systems or azulene fragments, all linked to the porphyrin core by a triple bond.
   
   
   • Ru complexes containing polycyclic thiophene-based 2,2’-bipyridyl ligands.
   
   
   • Diazafluorene-fullerene containing Ru complexes
   
   
   • polypyridines conjugated with electron-rich and electron-poor simple or benzofused heteroaromatic rings and their Ru complexes in order to enhance capacity of solar harvesting through higher Vis absorption and extension to the red and NIR range of the spectrum. The design of the above porphyrin systems and organometallic complexes will be guided by a theoretical TD-DFT investigation.
   
   
   • Preparation of thin films based on a nanostructured assembly of mesoporous TiO₂ and the dye, its application to a classical DSC solar cell.
   
   
   
   

The most promising molecular systems will be sent to the Università di Ferrara (Prof. Bignozzi) to be tested for DSCs solar cells.




2) BHJ:
the following new organometallic complexes will be synthesized and investigated for BHJ solar cells:

• Ru complexes of nitrogen-donor ligands linked to C60 or to a polycyclic fragment highly p-delocalized, as “acceptor partner”


• Pt complexes inside a polithiophene polymeric chain to be used as donor partners with respect the classical PCBM as acceptor.


• Ru, Ir or Pt complexes of new tris-oligothiophenylphosphanes either fully or partially capped at the terminal thiophene with electron-withdrawing groups to be used as donor partners.

These organometallic and coordination complexes, designed to exploit the flexibility of the metallorganic approach to tune the electronic levels, the absorption and charge transfer properties of donor/acceptor components will be tested as active materials for BHJ solar cells following the protocol reported below:




a) selection of the donor/acceptor systems
sorted out from studies of cyclic voltammetry and TD-DFT calculations;



b)
photoabsorption characterization
with absorption spectroscopy, photoluminescence, photoinduced absorptions etc.;




c) preparation of donor/acceptor photoactive composite thin films
via spin coating.



d)
assembling of BHJ solar cells and photovoltaic characterization
via I-V curves under dark and solar simulated white light, via photo-current action spectra under short circuit conditions.



For both DSCs and BHJ solar cells, the main photovoltaic parameters of the cells will be assessed: the short circuit current, the open circuit voltage, the fill-factor, the power conversion efficiency and the external quantum efficiency spectral response.