An investigation of the roles furan versus thiophene π-bridges play in donor–π-acceptor porphyrin based DSSCs

Dye-sensitized solar cells (DSSCs) continue to attract interest due to their lower cost production compared to silicon based solar cells and their improving power conversion efficiencies. Porphyrin-based sensitizers have become an important sub-class due to their strong absorption characteristics in the visible region, convenient modulation of properties through synthetic manipulation and class-leading power conversion efficiencies. In this article, we report the synthesis and characterization of two porphyrin-based dyes and their application as sensitizers in DSSCs. A thiophene and a furan moiety have been incorporated into the push–pull architecture as a π-bridge, allowing the systematic investigation of how these moieties influence the physical properties of the dyes and the performance of their resulting DSSCs. A significant difference in PCEs has been observed, with the furan containing dye (PorF, PCE = 4.5%) being more efficient than the thiophene-based analogue (PorT, PCE = 3.6%) in conjunction with the iodide/triiodide redox electrolyte

Robust High-performance Dye-sensitized Solar Cells Based on Ionic Liquid-sulfolane Composite Electrolytes

Novel ionic liquid-sulfolane composite electrolytes based on the 1,2,3-triazolium family of ionic liquids were developed for dye-sensitized solar cells. The best performing device exhibited a short-circuit current density of 13.4 mA cm(-2), an open-circuit voltage of 713 mV and a fill factor of 0.65, corresponding to an overall power conversion efficiency (PCE) of 6.3%. In addition, these devices are highly stable, retaining more than 95% of the initial device PCE after 1000 hours of light-and heat-stress. These composite electrolytes show great promise for industrial application as they allow for a 14.5% improvement in PCE, compared to the solvent-free eutectic ionic liquid electrolyte system, without compromising device stability

Influence of the Adsorption of Phycocyanin on the Performance in DSS Cells: and Electrochemical and QCM Evaluation

The influence of some coadsorbents and different pH values on the efficiency of DSS cells assembled with phycocyanin was evaluated using quartz crystal microbalance (QCM) and electrochemical techniques as impedance spectroscopy (EIS) and cyclic voltammetry (CV). Chlorophyll, heptadecanoic acid and 7.5 or 8.5 pH values were applied when nanostructured TiO2 electrode was dipped in the dye solution. Best efficiency conversion values were obtained when using fatty acids as coadsorbents, reaching a conversion efficiency of 0.04 % for open cells

A cockspur for the DSS cells: Erythrina crista-galli sensitizers

Dye sensitized solar cells were assembled employing a mixture of anthocyanins extracted from red ceibo's flowers. At the literature different extraction procedures are reported to extract anthocyanins from natural products and sensitize the cells. In order to compare them, different methods were followed to set the cells under the same conditions. Assembled cells showed very interesting conversion efficiency values, reaching a 0.73% value for extracts purified using C18 column, in open cells under illumination using a solar light simulator, 1 sun, 1.5 AM. Data reported herein prove that anthocyanins obtained from ceibo's flower, after simple further purification, might represent an excellent, cheap and clean alternative for the development of DSS cells. (C) 2017 Elsevier B.V. All rights reserved

Molecular Engineering of Pyrido[3,4-b]pyrazine-Based Donor-Acceptor-pi- Acceptor Organic Sensitizers: Effect of Auxiliary Acceptor in Cobalt- and Iodine-Based Electrolytes

Due to the ease of tuning its redox potential, the cobalt-based redox couple has been extensively applied for highly efficient dye-sensitized solar cells (DSSCs) with extraordinarily high photovoltages. However, a cobalt electrolyte needs particular structural changes in the organic dye components to obtain such high photovoltages. To achieve high device performance, specific requirements in the molecular tailoring of organic sensitizers still need to be met. Besides the need for large electron donors, studies of the auxiliary acceptor segment of donor-acceptor-pi-acceptor (D-A-pi-A) organic sensitizers are still rare in molecular optimization in the context of cobalt electrolytes. In this work, two novel organic D-A-pi-A-type sensitizers (IQ13 and IQ17) have been developed and exploited in cobalt-and iodine-based redox electrolyte DSSCs, specifically to provide insight into the effect of pi-bridge modification in different electrolytes. The investigation has been focused on the additional electron-withdrawing acceptor capability with grafted long alkoxy chains. Optoelectronic transient measurements have indicated that IQ17 containing a pyrido[3,4-b]pyrazine moiety bearing long alkoxyphenyl chains is more suitable for application in cobalt-based DSSCs

Effect of Sensitizer Adsorption Temperature on the Performance of Dye-Sensitized Solar Cells

Employing a mesoscopic titania photoanode whose bilayer structure was judiciously selected to fit the optoelectronic characteristics of the Ru-based heteroleptic complex Na-cis-Ru(4,4'-(5-hexyltiophen-2-yl)-2,2'-bipyridine)(4-carboxylic-acid-4'-carboxylate-2,2'-bipyridine)(thiocyanate)(2), coded as C101, we investigated the effect of temperature for dye adsorption on the photovoltaic performance of dye-sensitized solar cells (DSCs). We found a significant efficiency enhancement upon lowering the temperature applied during the sensitizer uptake from solution. When the dye adsorption was performed at 4 degrees C, the photovoltaic performance parameters measured under standard reporting conditions (AM1.5 G sunlight at 1000 W/m(2) intensity and 25 degrees C), i.e., the open circuit voltage (V-oc), the short circuit photocurrent density (J(sc)), the fill factor (FF), and consequently the power conversion efficiency (PCE), improved in comparison to cells stained at 20 and 60 degrees C.Results from electrochemical impedance spectroscopy (EIS) and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) show that the self-assembled layer of C101 formed at lower temperature impairs the back-electron transfer from the TiO2 conduction band to the triiodide ions in the electrolyte more strongly than the film produced at 60 degrees C. Profiting from the favorable influence that the low-temperature dye uptake exerts on photovoltaic performance, we have realized DSCs showing a power conversion efficiency of 11.5%

A vacuum flash-assisted solution process for high-efficiency large-area perovskite solar cells

Metal halide perovskite solar cells (PSCs) currently attract enormous research interest because of their high solar-to-electric power conversion efficiency (PCE) and low fabrication costs, but their practical development is hampered by difficulties in achieving high performance with large-size devices. We devised a simple vacuum flash-assisted solution processing method to obtain shiny, smooth, crystalline perovskite films of high electronic quality over large areas. This enabled us to fabricate solar cells with an aperture area exceeding 1 square centimeter, a maximum efficiency of 20.5%, and a certified PCE of 19.6%. By contrast, the best certified PCE to date is 15.6% for PSCs of similar size. We demonstrate that the reproducibility of the method is excellent and that the cells show virtually no hysteresis. Our approach enables the realization of highly efficient large-area PSCs for practical deployment

Porphyrin Sensitizers Bearing a Pyridine-Type Anchoring Group for Dye-Sensitized Solar Cells

Three novel efficient donor-acceptor porphyrins, MH1-MH3, with a pyridine-type acceptor and anchoring group were synthesized and their optical, electrochemical, and photovoltaic properties investigated. Replacing the commonly used 4-carboxyphenyl anchoring group with 2-carboxypyridine, 2-pyridone, and pyridine did not significantly change the absorption and electrochemical properties of the porphyrin dyes. These new porphyrin dyes MH show power conversion efficiencies of 8.3%, 8.5%, and 8.2%, which are comparable to that of the benchmark YD2-o-C8 (eta = 8.25%) under similar conditions. It was demonstrated that 2-carboxypyridine is an efficient and stable anchoring group as MH1 and showed better cell performance and long-term stability than YD2-o-C8 under light soaking conditions

Stable and Efficient Organic Dye-Sensitized Solar Cell Based on Ionic Liquid Electrolyte

Dye-sensitized solar cells (DSCs) for outdoor applications must show both high efficiency and long-term stability. Here we introduce a co-sensitized, ionic liquid electrolyte-based DSC meeting these requirements. A key feature of our embodiment is the concerted action of two judiciously designed organic dyes, whose co-adsorption at the surface of a mesoscopic TiO(2 )scaffold results in the formation of a compact and highly robust self-assembled monolayer, harvesting sunlight across the whole visible region and converting the photons into charges with near-unity quantum efficiency. Apart from producing a high photocurrent, the dense dye layer blocks the back electron transfer from TiO2 to the redox electrolyte, increasing the photovoltage. This allows for the first time to attain a solar to electric power-conversion efficiency of 10% with an ionic liquid-based DSC Remarkably, the co-sensitized cell is stable under both full-sunlight soaking at 60 degrees C and heat stress at 85 degrees C for 1,000 hr

Influence of Ionic Liquid Electrolytes on the Photovoltaic Performance of Dye-Sensitized Solar Cells

New binary ionic liquid electrolytes based on 1-methyl-1-butylpyrrolidinium bis(trifluromethylsulfonyl)imide, 1-butylpyridinium bis(trifluromethylsulfonyl)imide, 1-methyl-3-ethylimidazolium bis(trifluromethylsulfonyl)imide, 1-methyl-3-ethylimidazolium tetracyanoborate, or 1-methyl-3-ethylimidazolium tricyanomethanide coupled with 1-methyl-3-propyl-imidazolium iodide were developed for dye-sensitized solar cells (DSCs). We examined these ionic liquid compositions in conjunction in conjunction with a diketopyrrolopyrrole-based donor-bridge acceptor dye (DPP-13) in dye-sensitized solar cells and also investigated the influence of adding lithium ions to the electrolyte to enhance the device performance. The best device exhibited a short-circuit current density of 15.2mAcm(-2), an open-circuit voltage of 678mV, and a fill factor of 71%, corresponding to an overall power conversion efficiency (PCE) of 7.1% under standard AM1.5G illumination at 100mWcm(-2)