Quenching our thirst

Adelaide Festival of Ideas session, Bonython Hall, 2.30pm, Sunday 9th October, 2011.Mina Gulihttp://adelaidefestivalofideas.com.au

Can a Carbon Price Save Us from Catastrophic Global Warming?

Adelaide Festival of Ideas session, Adelaide Town Hall, 12:00pm, Saturday 8th October, 2011. Chaired by Peter Mares. Scientists say significant climate change is already locked in and urgent action is needed to limit global temperature rises to 2°C – the target set by world leaders at Cancun. From next July, big emitters in Australia will pay $23 for every tonne of CO2 pumped into the atmosphere, but this still leaves coal-fired electricity far cheaper than gas, let alone renewable energy. Is it too little, too late? The task of cutting emissions poses a far bigger technical challenge than flying to the moon, so why don’t we have programs of Apollo-like proportions to further develop and deploy alternative energy? And why would we rule out an existing technology, like nuclear power?http://adelaidefestivalofideas.com.a

Role of Formamidinium (FA) In the Electronic and Thermodynamic Properties of MA(Pb: Sn)I3 Perovskites Using First Principle Calculations

Research on perovskite solar cells employing tin to replace or partially replace lead is becoming more popular because of the recent achievement of about 24.2% conversion efficiency for ecologically benign mixed Pb-Sn perovskite solar cells. However, a smaller effect on cohesive energies caused by the addition of a Sn metal has a considerable effect on thermodynamic properties of Pb-Sn perovskites under high-temperature effects. This paper investigates the role of formamidinium in the electronic and thermodynamic properties of MA(Pb: Sn)I3 perovskite alloy using density functional theory and CASTEP analysis through the Materials Studio. The intended A-cation perovskites have typical compounds FAxMA1-xSn0.5Pb0.5I3, where x=0, 0.2, 0.4 and 0.6. The control and FA-based perovskites were computed through CASTEP analysis from Material studio to determine the electronic and thermodynamic properties. The findings revealed an improved thermodynamic properties of FA added perovskites compared to control ones whereby no significant effect was found in band gap of MAPb0.5Sn0.5I3 perovskite due to addition of formamidinium. However, when x is above 0.5, the quality of the perovskite films declined, with a wide grain size dispersion and little crystallization as well as the phase impurities were detected. This necessitated a theoretical approach to achieve an optimum amount of FA additive required to improve the properties as well as providing a theoretical guidance for improving the properties of perovskite materials before carrying out experiments. Furthermore, the study predicts that it is possible to create a stable thermal MA(Pb: Sn)I3 alloy, if there is a well-thought-out design, which lays a foundation for the development and application of tin-lead mixed perovskite devices.   &nbsp

Dimension-Controlled Growth of Antimony-Based Perovskite-like Halides for Lead-Free and Semitransparent Photovoltaics

Antimony (Sb) has been identified as a promising candidate for replacing toxic lead (Pb) in perovskite materials because Sb-based perovskite-like halides exhibit not only intrinsic thermodynamic stability but also a unique set of intriguing optoelectronic characteristics. However, Sb-based perovskite-like halides still suffer from poor film morphology and uncontrollable halide constituents, which result from the disorder of the growth process. Herein, we propose a simple strategy to facilitate heterogeneous nucleation and control the dimension transformation by introducing bis(trifluoromethane)sulfonimide lithium (LiTFSI), which produces high-quality two-dimensional MA(3)Sb(2)I(9-x)Cl(x) films. As the spacer molecule among Sb-based pyramidal clusters, LiTFSI plays a role in forming a zero-dimensional intermediate phase and retarding crystallization. The slower dimension transformation well stabilizes the band gap of perovskite-like films with a fixed Cl/I ratio (similar to 7:2) and avoids random "x" values in MA(3)Sb(2)I(9-x)Cl(x) films prepared from the conventional method. Based on this method, Sb-based perovskite-like solar cells (PLSCs) achieve the highest recorded power conversion efficiency (PCE) of 3.34% and retain 90% of the initial PCE after being stored under ambient conditions for over 1400 h. More importantly, semitransparent Sb-based PLSCs with PCEs from 2.62 to 3.06% and average visible transparencies from 42 to 23% are successfully obtained, which indicates the great potential of the emerging Pb-free halide semiconductor for broad photovoltaic applications