Influence of alumina coating on transport and recombination in DSSCs with 1-methylbenzidazole as electrolyte additives

Xueqing Xu; Eva Maria Barea; Francisco Fabregat-Santiago; Juan Bisquert; Gang Xu

doi:10.1117/12.843448

12 October 2009 Influence of alumina coating on transport and recombination in DSSCs with 1-methylbenzidazole as electrolyte additives

Xueqing Xu, Eva Maria Barea, Francisco Fabregat-Santiago, Juan Bisquert, Gang Xu

Author Affiliations +

Proceedings Volume 7518, Photonics and Optoelectronics Meetings (POEM) 2009: Solar Cells, Solid State Lighting, and Information Display Technologies; 75180J (2009) https://doi.org/10.1117/12.843448
Event: Photonics and Optoelectronics Meetings 2009, 2009, Wuhan, China

Abstract

Nanocrystalline TiO₂ electrodes have been coated with alumina by being immersed into the solutions of aluminum isopropoxide and aluminum acetylacetonate respectively. The current-voltage characteristics of the TiO₂ and TiO₂/Al₂O₃ electrodes with 1-methylbenzimidazole (MBI) as additives in the electrolytes have been detected. It is found that the TiO₂/Al₂O₃ electrodes immersed in the solutions of aluminum isopropoxide (acetylacetone as coordinate ligands) for 1 hour have obtained great increase of J_sc, and owned the improved cells efficiency by 17%. To discover the origins of this improved photovoltaic performance and investigate the electron properties of the cells, the electrochemical impedance spectroscopy (EIS) has been used both in the dark and under illumination at different applied potentials. It is proposed that with the coating of Al₂O₃, the adsorption of MBI cations at the surface of TiO₂ electrodes decreased with the decrease of the applied potentials, which resulted in the downwards shift of the conduction band position of the TiO₂/Al₂O₃ electrodes at the lower potentials. As a result, the charge transfer resistance Rct decreased, and chemical capacitance C_films increased. Under illumination, the decrease of Rct became smaller and the conductivities became larger, which was attributed to the recombination inhibition effect of Al₂O₃ coating to the photoinjected electrons. As a consequence, the electron lifetime and the effective diffusion length for the TiO₂/Al₂O₃ electrodes increased, leading to the great increase of J_sc. It is indicated that with the coating of Al₂O₃, the decrease of J_sc could be overcome when MBI is used as the additives of the electrolyte.

Citation Download Citation

Xueqing Xu, Eva Maria Barea, Francisco Fabregat-Santiago, Juan Bisquert, and Gang Xu "Influence of alumina coating on transport and recombination in DSSCs with 1-methylbenzidazole as electrolyte additives", Proc. SPIE 7518, Photonics and Optoelectronics Meetings (POEM) 2009: Solar Cells, Solid State Lighting, and Information Display Technologies, 75180J (12 October 2009); https://doi.org/10.1117/12.843448

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KEYWORDS

Titanium dioxide

Electrodes

Coating

Dye sensitized solar cells

Resistance

Aluminum

Capacitance

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