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A thin-layer electrochemical cell is used to study the redox potential of sensitizers that are anchored on a mesophorous film, in conjunction with square-wave voltammetry. An efficiency of 6.6 percent is obtained for the first time in dye-sensitized nanocrsytalline solar cells with pure ionic liquid electrolytes, at an illumination of air mass (AM 1.5) sunlight.

Four organic donor-π-bridge-acceptor dyes containing phenothiazine as a spacer and cyanoacrylic acid as an acceptor were synthesized and tested as sensitizers in dye-sensitized solar cells (DSCs). The influence of iodide- and cobalt-based redox electrolytes on the photovoltaic device performance was investigated. In these new dyes, systematic π-conjugation was extended by inserting one or two phenothiazine moieties and investigated within the context of the resulting photoinduced charge-transfer properties. A detailed investigation, including transient absorption spectroscopy and quantum chemical methods, provided important information on the role of extended π-conjugation on the photophysical properties and photovoltaic device performance. Overall, the results showed that the extension of π-conjugation by one phenothiazine unit resulted in the best device performance owing to reduced recombination rates, whereas extension by two phenothiazine units reduced dye adsorption on TiO2 probably owing to the increase in molecular size. The performance of the dyes in DSCs was found to be a complex interaction between dye structure and size. [ABSTRACT FROM AUTHOR]

Ruthenium und Co: Ruthenium(II) ‐ Komplexe sind nach wie vor die „heißesten Kandidaten“ für Farbstoffsolarzellen, doch derzeit bekannte Ru ‐ Sensibilisatoren sind nicht mit CoII/III ‐ Elektrolyten kompatibel. Der Effekt einer Oberflächenisolierung auf die Leistungsfähigkeit einer Zelle wurde durch den Vergleich zweier cyclometallierter RuII ‐ Komplexe studiert. Der Ansatz zeigt ein allgemeines Prinzip für beispiellose Effizienzen bei der Kombination von RuII ‐ Sensibilisatoren mit einem Cobalt ‐ Elektrolyt. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSCs) have achieved impressive conversion efficiencies for solar energy of over 11% with an electrolyte that contains triiodide/iodide as a redox couple. Although triiodide/iodide redox couples work efficiently in DSCs, they suffer from two major disadvantages: electrolytes that contain triiodide/iodide corrode electrical contacts made of silver (which reduces the options for the scale up of DSCs to module size) and triiodide partially absorbs visible light. Here, we present a new disulfide/thiolate redox couple that has negligible absorption in the visible spectral range, a very attractive feature for flexible DSCs that use transparent conductors as current collectors. Using this novel, iodide-free redox electrolyte in conjunction with a sensitized heterojunction, we achieved an unprecedented efficiency of 6.4% under standard illumination test conditions. This novel redox couple offers a viable pathway to develop efficient DSCs with attractive properties for scale up and practical applications. [ABSTRACT FROM AUTHOR]

Nanocrystalline dye-sensitized solar cells (DSCs) are attracting considerable academic and industrial interest as low-cost, high-efficiency alternatives to the conventional solid p-n junction photovoltaic devices. A record of 10.6% total power conversion efficiency has recently been reached using a liquid organic electrolyte based on the iodide/triiodide redox couple. The recentachievement of long-term thermal stability by molecular-scale interface engineering has undoubtedly injected new momentum into this field. However, the sealing of volatile electrolytes in large scale modules still remains a critical issue in view of the practical application.

We elaborated a new electrolyte composition, based on butyronitrile solvent, that exhibits low volatility for use in dye-sensitized solar cells. The strong point of this new class of electrolyte is that it combines high efficiency and excellent stability properties, while having all the physical characteristics needed to pass the IEC 61646 stability test protocol. In this work, we also reveal a successftil approach to control, in a sub-Nernstian way, the energetics of the distribution of the trap states without harming cell stability by means of incorporating Nal in the electrolyte, which shows good compatibility with butyronitrile. These excellent features, in conjunction with the recently developed thiophene-based C106 sensitizer, have enabled us to achieve a champion cell exhibiting 10.0% and even 10.2% power conversion efficiency (PCE) under 100 and 51.2 mW·cm-2 incident solar radiation intensity, respectively. We reached >95% retention of PCE while displaying as high as 9.1% PCE after 1000 h of 100 mW·cm-2 light-soaking exposure at 60 °C. [ABSTRACT FROM AUTHOR]