Molecular Design of Anthracene-Bridged Metal-Free Organic Dyes for Efficient Dye-Sensitized Solar Cells

Metal-free org. dyes bridged by anthracene-contg. π-conjugations were designed and synthesized as new chromophores for dye-sensitized solar cells (DSSCs). Studies on the relation between the dye structure, photophys. properties, electrochem. properties and performances of the DSSCs are described. With the introduction of the anthracene moiety, together with a triple bond for the fine-tuning of mol. planar configurations and to broaden absorption spectra, the Jsc and Voc of DSSCs improved. The improvement of Jsc is attributed to a broader absorption spectra of the dyes with the anthracene moiety. EIS anal. reveals that the anthracene moiety suppresses charge recombination arising from electrons in TiO2 films with I3- ions in the electrolyte, thus improving Voc. From optimized mol. structures and DSSC test conditions, the dye TC501 shows a prominent solar energy conversion efficiency up to 7.03% (Jsc = 12.96 mA/cm2, VOC = 720 mV, ff = 0.753) under simulated AM 1.5 irradn. (100 mW/cm2).

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Ming Cheng, Ulf Anders Hagfeldt, Chao Yang
2010
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https://infoscience.epfl.ch/record/209560?ln=fr

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Cellule solaire à pigment photosensible

Une cellule solaire à pigment photosensible parfois appelée cellules Grätzel (en anglais, Dye-sensitized solar cell ou DSC) est un système photoélectrochimique inspiré de la photosynthèse végétale

Dye

A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye i

Liaison triple

En chimie, une liaison triple est une liaison chimique entre deux atomes impliquant six électrons de valence au lieu de deux dans une liaison covalente simple. On trouve notamment parmi les composés p

Influence of triple bonds as π-spacer units in metal-free organic dyes for dye-sensitized solar cells

Ulf Anders Hagfeldt, Chao Yang

Four metal-free org. sensitizers (TC101-TC104) with triple bonds in π-spacers and 5 ref. dyes (TC, TC105, TPC1, D5, and TH208) without triple bonds were applied in dye-sensitized solar cells to study the influence of triple bonds as π-spacer units on their photoelectrochem. properties and dye-sensitized solar cells (DSCs) performance. The introduction of triple bond could red shift the dye's absorption spectrum due to the enhancement of the π-spacer. However, the spectrum red shift is much less than that of the introduction of double bond because of more electronegativity of triple bond. The incident photon-to-current conversion efficiency reveals that the electron transfer yield (Φ(ν)ET) of DSCs becomes larger with the introduction of triple bond. Electrochem. impedance spectroscopy anal. reveals that the introduction of triple bond almost does not change the electron lifetimes in TiO2 films but decreases the effective diffusion lengths.

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π-Conjugated Donor-Acceptor Systems as Metal-Free Sensitizers for Dye-Sensitized Solar Cell Applications

Magdalena Anna Marszalek, Jacques-Edouard Moser, Mateusz Barnaba Wielopolski, Shaik Mohammed Zakeeruddin

High extinction coefficients and easily tunable spectral properties of π - conjugated donor-acceptor dyes are of superior advantage for the design of new metal- free organic sensitizers for applications in dye-sensitized solar cells. Ultrafast transient absorption spectroscopy on the femtosecond and nanosecond time scales provided deep insights into the dependence of charge carrier dynamics in fully organic dye/TiO2 systems on i) the donor-acceptor distance, ii) the π-conjugation length, and iii) the coupling to TiO2 by different anchoring groups. Importantly, the observed differences in charge transfer dynamics justify the variations of photovoltaic performances of the dyes as applied in solar cell devices. This leads to the conclusion that the photoconversion efficiencies strongly depend on a delicate interplay between the dyes’ building blocks, i.e. the donor, the π-conjugated spacer and the anchor/acceptor moieties, and may easily be tuned by molecular design.

E D P Sciences2013

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Triarylamine-based hydrido-carboxylate rhenium(i) complexes as photosensitizers for dye-sensitized solar cells

Ulf Anders Hagfeldt, Thomas Moehl, Kazuteru Nonomura, Lorenzo Veronese

Two new dyes based on a dinuclear rhenium complex and (E)-3-(5-(4-(bis(2,4-dibutoxy-[1,1-biphenyl]-4-yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic acid (namely D35) have been investigated as sensitizers for dye sensitized solar cells (DSSCs). Two different pyridazine ligands have been used, namely 4-pyridazine-carboxylic acid for dye 2 ([Re-2(-H)(-D35)(CO)(6)(-pyridazine-4-COOH)]) and 4-pyridazinyl-butanoic acid for dye 3 ([Re-2(-H)(-D35)(CO)(6)(-pyridazine-4-C3H6-COOH)]). The performances of these new dyes have been compared with those of the dye containing the bare 4-diphenylaminobenzoic acid, namely TPA, as the ancillary ligand (dye 1). Compared to dye 1, dyes 2 and 3 show an impressive tenfold increase in the absorption intensity in the range of 487-493 nm on TiO2 films, with great improvement of the light harvesting. Cyclic voltammetry experiments, performed on derivatives containing the methyl ester of the pyridazine ligands, show narrow electrochemical band gaps in the range of 1.36-1.84 eV. Solar cells with each dye have been prepared, using both iodide/triiodide and cobalt redox couples as the electrolytes, platinum or carbon as the counter electrodes, and TiO2 or SnO2 as the metal oxide photoelectrodes, respectively. The best DSSC results have been obtained using dye 3, with an overall solar-to-electric conversion efficiency of 3.5%, which greatly overcomes the previous result of 1.0% obtained for dye 1 in a not-optimized setup of the device. The performances of dye 3 are due to the presence of D35 ligand, which further suppresses the recombination of the injected electron with the electrolyte and with the oxidized state of the dye.

ROYAL SOC CHEMISTRY2019

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