Electrochemical Methods in Dye-Sensitized and Perovskite Solar Cell Research
Nick Vlachopoulos a, Anders Hagfeldt a, Michael Grätzel b
a Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechmique Fédérale de Lausanne, 1015 Lausanne, Switzerland
b Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechmique Fédérale de Lausanne, 1015 Lausanne, Switzerland
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Poster, Nick Vlachopoulos, 022
Publication date: 11th February 2019

The development of dye-sensitized and perovskite solar cells (DSSCs, PSCs) [1-3] is based on the synergy of several areas of science, notably synthetic chemistry, materials chemistry and physics, photochemistry- photophysics, and electrochemistry. Electrochemical methods have been used for the characterization of entire DSSCs. Alternatively, they have been used for the characterization of DSSC or PSC components and can provide important feedback to the researchers involved in the development and optimization solar cell materials. Some important examples from the authors’ research obtained over the past 30 years will be cited in this presentation, which will be focused on the electrochemical characterization of solar cell components and the preparation of some of them by electrochemical deposition. In a DSSC, at first, the electrochemical reversibility and redox potential of the dye should be determined, with the dye either in the dissolved state or adsorbed at the electrode. In the latter case, the electrochemical reactivity is based on lateral electron transfer (electron hopping) between dye molecules [4,5]. In fact, the redox potential obtained in the latter case is more relevant for the DSSC device, and it can be substantially different from that related to the dissolved dye. The semiconductor properties of the mesoporous dye substrate material itself can be characterized by cyclic voltammetry in order to ascertain that the material itself is essentially electrochemically inert at electrode potentials approaching the redox potential of the proposed mediator. Other studies concerning the photoelectrode, involve the investigation of the effectiveness of the thin semiconductor blocking layer or underlayer (UL) interposed between the mesoporous layer and the transparent conducting oxide (TCO)-coated glass support, which is often necessary toward suppressing the reactivity of TCO electrons toward the redox mediator in a DSSC or the solid charge-transport material in a PSC. Anodic electrochemical deposition can also be used in order to generate a variant of UL, by anodic electrooxidation of TiCl3 in an acidic solution [6].  As regards redox mediators in liquid DSSC electrolytes, the redox potential and the diffusion coefficient can be determined by cyclic voltammetry at stationary electrodes and rotating disk voltammetry at a microelectrode respectively, in presence of inert supporting electrolyte. Additionally, the effective diffusion coefficient (including migration effects) of the mediator in the electrolytes used in the DSSC device can be determined by linear scan voltammetry either at microelectrodes or at symmetrical thin-layer solar cells (TLSCs) with two identical conductive electrodes. The electrocatalytic properties of the counter electrode (CE) can be investigated either by cyclic voltammetry as well as by impedance spectroscopy, in the latter case at TLCs with two identical electrodes composed of the same electrocatalyst. Morevover, some types of  solar cell CEs can be prepared by electrodeposition, for example thin layers of a noble metal or a conducting polymer on a metal or TCO substrate [7]. Finally, in a DSSC electrodeposition can be used in order to generate in-situ, into to the porous of the mesoscopic oxide, a conducting polymer hole conductor, e.g. PEDOT, thereby ensuring intimate contact between the dye and the hole conductor [4,8].

 

 

 

© Fundació Scito
We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info