Progress on lead-free metal halide perovskites for photovoltaic applications: a review

ABSTRACT: Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low. This fact opened up a new research field on lead-free metal halide perovskites, which is currently remarkably vivid. We took this as incentive to review this emerging research field and discuss possible alternative elements to replace lead in metal halide perovskites and the properties of the corresponding perovskite materials based on recent theoretical and experimental studies. Up to now, tin-based perovskites turned out to be most promising in terms of power conversion efficiency; however, also the toxicity of these tin-based perovskites is argued. In the focus of the research community are other elements as well including germanium, copper, antimony, or bismuth, and the corresponding perovskite compounds are already showing promising properties. GRAPHICAL ABSTRACT: [Image: see text

New π-electron donor (1,4-thioxane-2,3-diyldithio)ethylenedithiotetrathiafulvalene (ETOEDT-EDT-TTF) and its derivatives. Synthesis and characterization

We report more efficient way for the synthesis of 4,5-(1,4-oxathiane-2,3-diyldithio)-1,3-dithiole-2-thione and three new TTF-derived nonsymmetrical electron donors: the (1,4-thioxane-2,3-diyldithio)ethylenedithiotetrathiafulvalene (ETOEDT-EDT-TTF), (1,4-thioxane-2,3-diyldithio)propylenedithiotetrathiafulvalene (ETOEDT-PDT-TTF), and (1,4-thioxane-2,3-diyldithio)dimethylenedithiotetrathiafulvalene (ETOEDT-DMDT-TTF). For the first time we also present extended studies of the molecular structure, vibrational and electronic excitations of the donors. Based on theoretical and experimental Raman and infrared spectra as well as analysis of electron excitations of three new TTF-derived donors their spectral properties were described and discussed. © 2007 Elsevier Ltd. All rights reserved

First sitting of the Government Savings Bank's new board, New South Wales, ca. 1925, 2 [picture].

Title devised from accompanying information where available.; Part of the: Fairfax archive of glass plate negatives.; Fairfax number: 4385.; From left: Mr M.B. Young, Sir Clifton Love, President Mr W.H. O'Malley Wood, Vice President Sir John Butters, Sirn William Vicards and Former Commissioner Mr H.D. Hall; Also available online at: http://nla.gov.au/nla.pic-vn6251426; Acquired from Fairfax Media, 2012