Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells.

Quentin Huaulmé,Nicolas Leclerc,David Beljonne,Outi Vilhelmiina Kontkanen,Alexandra Sutter,Renaud Demadrille,Gilles Ulrich,Cyril Aumaitre

doi:10.3762/bjoc.15.169

Abstract

We report two novel functional dyes based on a boron-dipyrromethene (BODIPY) core displaying a panchromatic absorption with an extension to the near-infrared (NIR) range. An innovative synthetic approach for preparing the 2,3,5,6-tetramethyl-BODIPY unit is disclosed, and a versatile way to further functionalize this unit has been developed. The optoelectronic properties of the two dyes were computed by density functional theory modelling (DFT) and characterized through UV–vis spectroscopy and cyclic voltammetry (CV) measurements. Finally, we report preliminary results obtained using these functional dyes as photosensitizers in dye-sensitized solar cells (DSSCs).

Highlights

The past two decades have witnessed tremendous efforts to develop alternative photovoltaic (PV) technologies
In order to maximize the photocurrent density in a dyesensitized solar cells (DSSCs) device, the sensitizer has to display high molar absorption coefficients, ideally along the entire visible range
The one-electron energy diagram reported in Figure 2 shows that: (i) Grafting the triphenylamine donor moieties on the thiophene-vinylene bridge only slightly lowers the ionization potential of the dyes, compare (1,2) to (3,4); this is explained by the fact that the highest occupied molecular orbital (HOMO) molecular orbital mostly spreads on the BODIPY-vinylthiophene core of the molecules, with only slight contributions from the TPA units (ii) The position of the methyl groups has by far a larger impact on the electron affinity of the molecules, which is substantially increased when going from 2 to 1, and from 4 to 3

Summary

Introduction

The past two decades have witnessed tremendous efforts to develop alternative photovoltaic (PV) technologies. [7] but these molecules reveal low absorption coefficients over the visible range They contain a rare and a relatively high-cost element (Ru) and their plausible toxicity restrains their development at the industrial level. BODIPY dyes are one of the most extensively studied class of fluorophores due to their unique properties, including high absorption coefficients in the visible and NIR ranges, high fluorescence quantum yields, and high stability in various media They display a very versatile chemistry, allowing the fine tuning of all their physical and optical properties [14]. The latter lies close to the conduction band of the electron-transporting oxide, limiting the driving force of electronic injection, and the overall efficiency of the resulting solar cell

Design and DFT calculations

Synthesis

Optical properties

Electrochemical characterization

DSSCs fabrication and device performances

Conclusion