Jacqueline Cole1 2 3

1, University of Cambridge, Cambridge, , United Kingdom
2, STFC Rutherford Appleton Laboratory, Harwell, , United Kingdom
3, Argonne National Laboratory, Argonne, Illinois, United States

The transparent and low-cost nature of dye-sensitised solar cells (DSCs) affords them niche prospects for electricity-generating windows in energy-sustainable buildings. Despite their vast industrial potential, innovation is being held up by a lack of suitable dyes. Better dyes can only be realized if we can better understand how the dye...TiO2 interface of a DSC working electrode functions at the molecular level. Previously, no materials characterization technique had managed to probe the interfacial structure of a DSC working electrode while in its full device assembly, where it exists as a buried interface; yet this information is critically important since the structure will undoubtedly change once embedded in its device environment. To this end, this talk presents the world’s first report of an in situ neutron reflectometry study that determines the dyeTiO2 interfacial structure of the DSC working electrode while housed in its device environment [1]. The high-performance DSC dye, MK-2 and its molecular building block, MK-44 are the case studies [2]. Probing this buried interface within its device environment sets this study apart from surface chemistry approaches that characterize the exposed interfaces. We show how the electrolyte modulates the structure of these buried interfaces, and thence its photovoltaic properties. The finding that this structural modulation is only observed once the DSC working electrode is atomically probed in its device environment highlights the need to characterize these buried interfaces directly, if DSC functionality is to be properly understood at the molecular scale.

[1] J. McCree-Grey, J. M. Cole, S. A. Holt, P. J. Evans, Y. Gong, “Dye...TiO2 Interfacial Structure of Dye-Sensitised Solar Cell Working Electrodes Buried under a Solution of I-/I3- Redox Electrolyte”, Nanoscale, 9 (2017) 11793-11805.

[2] J. M. Cole, M. A. Blood-Forsythe, T. C. Lin, P. Pattison, Y. Gong, A. Vazquez-Mayagoitia, P. G. Waddell, L. Zhang, N. Koumura, S. Mori, “Discovery of SCN intramolecular bonding in a thiophenylcyanoacrylate-based dye: realizing charge transfer pathways and dyeTiO2 anchoring characteristics for dye-sensitized solar cells”, ACS Appl. Mater. & Interfaces, 9 (2017) 25952-25961.