Addition of 4-tert-butylpyridine (4TBP) to redox electrolytes used in dye-sensitized TiO2 solar cells has a large effect on their performance. In an electrolyte containing 0.7 M LiI and 0.05 M I2 in 3-methoxypropionitrile, addition of 0.5 M 4TBP gave an increase of the open-circuit potential of 260 mV. Using charge extraction and electron lifetime measurements, this increases could be attributed to a shift of the TiO2 band edge toward negative potentials (responsible for 60% of the voltage increase) and to an increase of the electron lifetime (40%). At a lower 4TBP concentration the shift of the band edge was similar, but the effect on the electron lifetime was less pronounced. The working mechanism of 4TBP can be summarized as follows: (1) 4TBP affects the surface charge of TiO2 by decreasing the amount of adsorbed protons and/or Li+ ions. (2) It decreases the recombination of electrons in TiO2 with triiodide in the electrolyte by preventing triiodide access to the TiO2 surface and/or by complexation with iodine in the electrolyte.

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The solar‐to‐electric power‐conversion efficiency (η) of dye‐sensitized solar cells can be greatly enhanced by integrating a mesoporous, nanoparticle‐based, 1D photonic crystal as a coherent scattering layer in the device. The photogenerated current is greatly improved without altering the open‐circuit voltage of the cell, while keeping the transparency of the cell intact. Improved average η values between 15% and 30% are attained.

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Films of the hybrid lead halide perovskite CH3NH3PbI3 were found to react with pyridine vapor at room temperature leading to complete bleaching followed by recrystallization of the film.

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A multicell is presented as a tool for testing material components in encapsulated dyesensitized solar cells. The multicell is based on a four-layer monolithic cell structure and an industrial process technology. Each multicell plate includes 24 individual well-encapsulated cells. A sulfur lamp corrected to the solar spectrum has been used to characterize the cells. Efficiencies up to 6Á8% at a light-intensity of 1000 W/m 2 (up to 7Á5% at 250 W/m 2 ) have been obtained with an electrolyte solution based on -butyrolactone. Additionally, a promising long-term stability at cell efficiencies close to 5% at 1000 W/m 2 has been obtained with an electrolyte based on glutaronitrile. The reproducibility of the cell performance before and after exposure to accelerated testing has been high. This means that the multicell can be used as an efficient tool for comparative performance and stability tests. INTRODUCTIONT he electrochemical dye-sensitized photovoltaic cell (dye PV cell) technology differs from conventional solar cell technologies in fundamentals and device components. In a dye PV cell, the light absorption and the charge-transport processes are separated, with a dye absorbing the light, whereupon the excited electrons are injected into, and transported through, a semi-conducting nanocrystalline film onto which the dye is adsorbed. A redox-couple dissolved in an electrolyte is used to reduce the oxidized dye. At the counter electrode, the opposite reaction takes place, creating a regenerative system. Thus, key components of a dye PV cell are the nano-structured semiconductor, the light-absorbing dye, the counter electrode, and the electrolyte. As a result of