A new nearly cubic NH 2 CHNH 2 PbI 3 (FAPbI 3 ) perovskite was synthesized for the mesoscopic solar cells. The measured band gap of bulk FAPbI 3 is 1.43 eV and it is therefore potentially superior than the CH 3 NH 3 PbI 3 (MAPbI 3 ) as the light harvester. A homogeneous FAPbI 3 perovskite layer was deposited on the TiO 2 surface by utilizing the in situ dipping technology. As a result, a high efficiency of 7.5% was achieved using P3HT as the hole transport material. The nearly cubic crystal structure and appropriate band gap render this new FAPbI 3 perovskite extremely attractive for next generation high-efficiency low-cost solar cells.

In the past few years, the advent of lead halide perovskite solar cells (PSCs) has revolutionized the prospects of the third- generation photovoltaics and the reported power conversion efficiency (PCE) has been updated to 22%. Nevertheless, two main challenges, including the poisonous content of Pb and the vexing instability toward water, still lie between the lab-based PSCs technology and large scale commercialization. With this background, we first evaluated Pb concentration from the rainwater samples polluted by three types of markets promising PSCs with inductively coupled plasma mass spectrometry measurements (ICP-MS) as a case study. The influence of possible conditions (pH value and exposure time) on the contents of Pb from the three PSCs was systematically compared and discussed. Furthermore, an optimized glutathione functionalized gold nanoparticles (GSH-AuNPs) colorimetric sensing assay was used to determine Pb leaking from PSCs for the first time. The Pb-induced aggregation of sensing assay could be monitored via both naked eye and UV-vis spectroscopy with a detection limit of 15 and 13 nM, which are all lower than the maximum level in drinking water permitted by WHO. The quantitative detection results were compared and in good agreement with that of ICP-MS. The results indicate that the content of Pb from three PSCs are in the same order of magnitude under various conditions. By the use of the prepared GSH-AuNPs self-assembled sensing assay, the fast and on-site detection of Pb from PSCs can be realized.

Due to lots of carboxyl groups introduced uniformly on the carbon nanotube (CNT) surface, platinum-ruthenium nanoparticles were highly dispersed on the 3,4,9,10-perylene tetracarboxylic acid-functionalized CNT surface and showed improved electrochemical properties for methanol electrooxidation.

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