BNL Home
August 2016
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  1. Center for Functional Nanomaterials Seminar

    11 am, CFN, Bldg 735, Conference Room A, 1st Floor

    Hosted by: '''''Mircea Cotlet'''''

    Perovskite Photovoltaics: Renewable energies are one of the most important components of the global new energy strategy. Utilizing the power of the sun is one of the most viable ways to solve the foreseeable world's energy crisis. With increasing attention toward carbon-neutral energy production, solar electricity, or photovoltaic (PV) technology, is the object of steadily growing interest. The International Energy Agency's technology roadmap estimates that by 2050, PV will provide ~ 11% of all global electricity production & avoid 2.3 gigatonnes of CO2 emissions per year. A new solar cell material has evolved with transformative potential with laboratory efficiencies of 19.7%. Perovskite absorber materials are very inexpensive to synthesize & simple to manufacture, making them an extremely commercially viable option. Solar cell efficiencies of devices using these materials have increased from 3.8% in 2009 to a certified 20.1% in 2015, making this the fastest-advancing solar cell technology to date. These devices are also known for their high photon absorptivity, ideal direct band gaps with superior carrier charge transports, & cost-effective modes of fabrication scalability. Gama-ray Radiation Detectors: Cadmium zinc telluride (Cd1-xZnxTe or CZT), a ternary semiconductor material is well suited for good charge collection efficiency & high energy resolution room temperature x- & gamma (γ) -ray radiation detectors. In addition, these detectors can be small in size & have fast timing characteristics. Key semiconductor material properties required for high efficiency, & high energy resolution radiation detectors operable at room temperature are a high atomic number, ideal bandgap & low leakage current, high carrier mobility-lifetime (µτ) product to ensure complete charge collection, & high-purity, homogenous, & defect-free. CZT is recognized as one of the leading materials for fabrication.

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  1. Center for Functional Nanomaterials Seminar

    1:30 pm, CFN, Bldg. 735, 1st floor, conf. rm. A

    Hosted by: 'Alexei Tkachenko'

    Self-assembling materials have been extensively studied in recent years. It is now possible to achieve a considerable degree of complexity using simple building blocks. For example, using computer simulations, we have found that 2D particles with regularly arranged 'patches' spontaneously form dodecagonal quasicrystals in certain conditions. I will show that the quasicrystal phase has the lowest free energy over a range of conditions and is stabilized by its greater configurational entropy over the crystalline phases. The patchy particles of the model can be thought of as a coarse-grained representation of DNA multi-arm 'star' motifs. I will present several possible design strategies to construct soft two-dimensional DNA-based quasicrystals. However, simple building blocks such as these can only go so far and self-assembling truly 'complex' structures requires us to introduce more distinct building blocks into the system, which makes the problem of self-poisoning ever more difficult to counter. In 2012, Ke and co-workers reported that DNA bricks successfully self-assembled into structures containing not just a handful, but hundreds of distinct components [Science 338, 1117 (2012)]. However, it is not immediately obvious why such self-assembly should succeed where colloidal systems have failed. In my talk, I will present our computational and theoretical work explaining how nucleation governs the self-assembly of these many-component systems and the role this plays in the rational design of the target structure.

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  1. SEP

    8

    Thursday

    CFN Colloquium

    "Billions and Billions of molecules: Exploring chemical space for functional molecular materials"

    Presented by Alan Aspuru-Guzik, Department of Chemistry and Chemical Biology, Harvard University

    4 pm, CFN, Bldg 735, Seminar Room, 2nd Floor

    Thursday, September 8, 2016, 4:00 pm

    Hosted by: ''''Qin Wu''''

    Many of the challenges of the twenty-first century are related to molecular processes such as the generation and storage of clean energy, water purification and desalination. These transformations require a next generation of more efficient, chemically stable, and non-toxic materials. Chemical space, the space of all possible synthesizable molecules, is practically infinite and promises to have relevant candidate functional molecules to address these challenges. One of the main goals of my research group is to develop understanding and tools for the exploration chemical space in order to accelerate the discovery of organic materials. Our design cycle is sped up by the constant interaction of theoreticians and experimentalists, the use of high-throughput computational techniques, machine learning, and the development of specialized big data tools. We have had recent successes in theoretically predicting and experimentally confirming in record times top performers in the areas of organic electronics, organic flow batteries and organic light-emitting diodes. In this talk, I will discuss what I consider are the key factors related with a successful high-performance screening approach as illustrated by these three different applications. I will end by discussing the future prospects and challenges associated with developing appropriate metrics for the cartography of chemical space.