Molecular engineering of largely π-extended metal-free sensitizers containing benzothiadiazole units: Approaching 10% efficiency dye-sensitized solar cells using iodine-based electrolytes. (August 2016)

• Record Type: Journal Article
• Authors: Grisorio, Roberto; De Marco, Luisa; Giannuzzi, Roberto; Gigli, Giuseppe; Suranna, Gian Paolo
• Is Part Of: Dyes and pigments. Volume 131(2016)
• Page Start: 282
• Page End: 292
• Publication Date: 2016-08
• Subjects: D–A–π–A sensitizer -- Dye-sensitized solar cell -- Density functional theory -- Iodine-based electrolyte; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2016.04.020
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Based on the structural motif of a robust organic dye, new largely π-extended organic sensitizers for dye-sensitized solar cells (DSSCs) have been designed to optimize the interactions between the dye/TiO2 layer and the redox electrolyte. The molecular tailoring was performed by i) positioning an alkyl chain onto the π-spacer and ii) increasing the bulkiness of the electron-donor. A deep theoretical investigation reveals that the main electronic transitions of the three dyes own only a weak charge-transfer character. Notwithstanding these unusual photo-excitation dynamics experimentally supported by solvatochromism, impressive photovoltaic performances are obtained for the three sensitizers, reaching power conversion efficiencies up to 9.8% under 1.0 sun illumination, that were remarkably higher than those shown by N719 standard. This result represents one of the highest performances exhibited by fully organic sensitizers employing the I – /I3 – redox shuttle. Graphical abstract: Highlights: New D-A-π-A organic sensitizers were structurally tailored to enhance DSSC performances. TD-DFT calculations were performed for providing insights into the excitation dynamics. Photophysical and electrochemical properties are in good agreement with the theoretical results. DSSC performances up to 9.8% in terms of PCE were obtained.