With an efficiency recorded over 14%, DSSCs based on mesoporous nanocrystalline TiO₂ and as regard to the cost effective of their elaboration,are at present the most powerful. Nevertheless, the mechanism within DSSCs iscomplex and some key points still remain to overcome; especially theimprovement of the charge transfer processes at dye/electrolyte and TiO₂/dye interfaces in conjunction with the objective of decreasing the charge recombination. Different strategies have been developed to break up these problems, for example by modifying the photo-anode structure, by introducing a semi-conductor as compact blocking layeror by developing efficient sensitizers or replacing the liquid redox mediator I₃^-/I^- used as hole transporting materials (HTM). Among them, conducting polymers (CP) generated by in-situ electro-assisted photo-deposition (EPD) process from an organic monomer in organic solution, are used as HTM [1] in thin layer covering the dye modified TiO₂ electrode. Using this strategy, where the contact between the dye and the HTM is strong, we recently produced CP from in-situ EPD in aqueous medium leading to an efficient environmental friendly DSSC due to the high charge transfer [2-4].

Based on this feedback, in this work we completely removed the energy barrier of charges transfer by designing a novel metal-free organic dye covalently linked to an organic monomer. After modification of the TiO₂ surface by adsorption of the new dye, the linked monomer was co-polymerized by the in-situ EPD process both in organic and aqueous micellar solution, leading to a deposited CP (used as HTM) covalently linked to the adsorbed dye molecule. Based on the common donor-π linker-acceptor (D-π-A) configuration, the new dye structure consists of triarylamine and thiophene covalently linked to two carbazole units. Carbazole, known for its interesting photochemical properties, is not only used as donor group [5] but also as monomer for co-polymerization with 3,4-ethylenedioxythiophene (EDOT) monomer dissolved in solution in order to remove the energy barrier at the Dye/HTM interface. The preliminary results show that in-situ EPD is more efficient in aqueous micellar medium than in organicone, which lead to a higher photoconversion efficiency DSSC device while being cost effective and environmental friendly. These third generation DSSCs are thus involved in a promising future in the field of alternative sustainable energy.

[1]K. Murakoshi et al., Chem Lett. (1997), 471–472[2] J. Zhang et al., J. Phys. Chem. Lett. (2013), 4 (23), 4026-4031, [3] L. Yang et al., J. Phys. Chem. C, (2014), 118 (30), 16591–16601, [4] J.Zhang et al., Electrochimica Acta (2015) 179, 220–227. [5] J.Tang et al., Energy Environ. Sci., (2010), 3, 1736–1745