Quantum Times

Simpler method for building varieties of nanocrystal superlattices

Collaboration by chemists, physicists and materials scientists at the University of Pennsylvania has created a simple and inexpensive method to rapidly grow centimeter-scale membranes of binary nanocrystal superlattices, or BNSLs, by crystallizing a mixture of nanocrystals on a liquid surface.The study demonstrates a new and spontaneous way to grow long-range-ordered BNSL membranes with rigorous control of nanocrystal size, shape and concentration by combining two types of nanocrystals and assembling them during a drying stage at the surface of a liquid under normal conditions.The method overcomes several limitations of the existing assembly strategies and produces large, free-standing membranes that can be transferred to any desired substrate such as silicon wafers, glass slides and plastic substrates, allowing the nanocryatalline films to be introduced at any stage in the device fabrication process.   The team demonstrated the potential for integrating these novel materials by growing millimeter-scale super

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