A Combined Experimental and Computational Investigation of Anthracene Based Sensitizers for DSSC: Comparison of Cyanoacrylic and Malonic Acid Electron Withdrawing Groups Binding onto the TiO₂ Anatase (101) Surface

Abstract

Four anthracene based sensitizers, 3-(anthracene-9-yl)-2-cyanoacrylic acid (M1), 2-cyano-3-(10-methoxyanthracene-9-yl)acrylic acid (M2), 2-(anthracene-9-ylmethylene) malonic acid (M3), and 2-((10-methoxyanthracene-9-yl)methylene)malonic acid (M4) were designed and synthesized to understand the binding modes of anchoring groups ( and ) on the nanocrystalline TiO 2 (101) surface and on the efficiency of dye-sensitized solar cells (DSSCs). All four sensitizers have been fully characterized using ATR-FTIR, UV-vis, and CV. These sensitizers were tested in DSSCs using 0.05 M I 2 , 0.5 M 1,2-dimethyl-3-n-propylimidazolium iodide (DMPI), and 0.5 M lithium iodide (LiI) in methoxypropionitrile (MPN) redox electrolyte. The sensitizers having a monocarboxylic acid group, i.e., M1 and M2, have shown marginally higher IPCE and efficiency than M3 and M4 having dicarboxylic acid groups. To have a detailed understanding of this behavior, the adsorption and binding energies to the TiO 2 surface of these dyes have been investigated using computational techniques (periodic DFT). The studies show that the cyanoacrylic acid anchoring group has a stronger binding to the TiO 2 surface compared to the malonic acid anchoring group.

Efficiency enhancement of black dye-sensitized solar cells by newly synthesized D–π–A coadsorbents: a theoretical study

“…34,[44][45][46][47] We therefore determined, in the first step, the geometry of deposition through BB-type adsorption, using periodic slab model for vacuum and cluster method for solvent calculations. The optimized geometries of deposition on (TiO2) 38 cluster surface in acetonitrile is shown in Fig.…”

The Adsorption Geometry and Electronic Structure of Organic Dye Molecule on TiO2(101) Surface from First Principles Calculations

“…The calculated Eads energies of these adsorption configurations indicate that the BB-type configuration is the most favorable mode of dissociative adsorption for NKX-2554 dye, [15] with a positive Eads of 1.29 eV. The optimized geometrical structure of the NKX-2554 dye adsorbed on pure and I-doped TiO 2 (101) slab are given in Fig.…”

“…[14] The adsorption of NKX-2554 dye on anatase (101) surface has been extensively studied to search for the energetically most favorable structure of adsorbed dye/TiO 2 systems. [15] The possible dissociative adsorption modes for the cyanoacrylic acid derivative are shown in Fig. 1c.…”

Novel Organic Sensitizers Containing 2,6-Difunctionalized Anthracene Unit for Dye Sensitized Solar Cells

“…Recently, a few anthracene-based derivatives have been reported as sensitizers for DSSCs [32][33][34]. However, all previous reports have focused on anthracene derivatives substituted on C9 and C10.…”

“…However, all previous reports have focused on anthracene derivatives substituted on C9 and C10. An alkynyl or alkenyl substituent has to be introduced at C9 and/or C10 in order to avoid serious steric congestion of the anthracene moiety with its neighboring aromatic rings, which results in a drop of the cell efficiency [32][33][34]. Recently, we reported new organic dyes containing a 1,4-naphthyl entity in the conjugation bridge [35].…”