Direct Conversion of CH3NH3PbI3 from Electrodeposited PbO for Highly Efficient Planar Perovskite Solar Cells.

Organic-inorganic hybrid perovskite materials have recently been identified as a promising light absorber for solar cells. In the efficient solar cells, the perovskite active layer has generally been fabricated by either vapor deposition or two-step sequential deposition process. Herein, electrochemically deposited PbO film is in situ converted into CH3NH3PbI3 through solid-state reaction with adjacent CH3NH3I layer, exhibiting a large-scale flat and uniform thin film with fully substrate coverage. The resultant planar heterojunction photovoltaic device yields a best power conversion efficiency of 14.59% and an average power conversion efficiency of 13.12 ± 1.08% under standard AM 1.5 conditions. This technique affords a facile and environment-friendly method for the fabrication of the perovskite based solar cells with high reproducibility, paving the way for the practical application.

Electrodeposition of PbO and its in situ conversion to CH3NH3PbI3 for mesoscopic perovskite solar cells.

The perovskite CH3NH3PbI3 was prepared on a mesoscopic TiO2 film, starting from electrodepositing PbO, to iodination to PbI2, and then interdiffusion reaction with CH3NH3I. The as-prepared film was used as a light absorber for the perovskite solar cells, exhibiting a high PCE of 12.5% under standard AM 1.5 conditions.

[Fluorescence spectroscopy characterization of asphaltene liquefied from coal and study of its association structure].

Structure and association of asphaltenes from coal direct hydroliquefaction were studied by fluorescence spectrometry and UV-Vis absorption spectrometry in this paper. The results indicate that asphaltene is aromatic mixtures mainly containing naphthalene nucleus and shows strong fluorescent characteristic. The forming of exciplex between asphaltene and solvent results in the red shift of fluorescence peak and fluorescence quenching of asphaltene that increases with the polarity and electron acceptability. The self-aggregation of asphaltene is formed by non-covalent bond interaction, so that the asphaltene liquefied at higher temperture that shows high aromaticity has stronger association than that liquefied at lower temperature. Aggregation of asphaltene has been found to be a gradual process, in which there is no critical aggregation constant observed, and the inflection point of the plot of apparent fluorescence intensity as a function of asphaltene concentration varies with the excitation wavelength.