Electrolyte/Dye/TiO2 Interfacial Structures of Dye-Sensitized Solar Cells Revealed by In Situ Neutron Reflectometry with Contrast Matching

• Published in: Langmuir Vol. 37; no. 5; pp. 1970 - 1982
• Main Authors: Deng, Ke, Cole, Jacqueline M, Cooper, Joshaniel F. K, Webster, John R. P, Haynes, Richard, Al Bahri, Othman K, Steinke, Nina-Juliane, Guan, Shaoliang, Stan, Liliana, Zhan, Xiaozhi, Zhu, Tao, Nye, Daniel W, Stenning, Gavin B. G
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.02.2021
• Subjects: Differential scanning calorimetry; Dyes and pigments; Electrolytes; Layers; Oxides; SOLAR ENERGY
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/acs.langmuir.0c03508

The nature of an interfacial structure buried within a device assembly is often critical to its function. For example, the dye/TiO2 interfacial structure that comprises the working electrode of a dye-sensitized solar cell (DSC) governs its photovoltaic output. These structures have been determined outside of the DSC device, using ex situ characterization methods; yet, they really should be probed while held within a DSC since they are modulated by the device environment. Dye/TiO2 structures will be particularly influenced by a layer of electrolyte ions that lies above the dye self-assembly. We show that electrolyte/dye/TiO2 interfacial structures can be resolved using in situ neutron reflectometry with contrast matching. We find that electrolyte constituents ingress into the self-assembled monolayer of dye molecules that anchor onto TiO2. Some dye/TiO2 anchoring configurations are modulated by the formation of electrolyte/dye intermolecular interactions. These electrolyte-influencing structural changes will affect dye-regeneration and electron-injection DSC operational processes. This underpins the importance of this in situ structural determination of electrolyte/dye/TiO2 interfaces within representative DSC device environments.