The Versatility of Light

16 Jun 2019

The preparation of shape-controlled semiconductor nanocrystals

© Jan Greune / LMU

The research carried out at the Chair fort Photonics and Optoelectronics have one thing in common: All their experiments involve nanocrystals. Dr. Lakshminarayana Polavarapu is one of the Project Leaders in the Chair. He has a PhD in chemistry, and his research interests focus on the Synthetic Chemistry and Optical Spectroscopy of Colloidal Nanocrystals. Keeping in mind that a nanometer means one billionth of a meter, it is extremely challenging to control the dimensions nanocrystals with atomic precision. Over the last few years he has developed several synthetic methods for the preparation of shape-controlled semiconductor nanocrystals. But that’s not all: “I am also responsible for the work safety and instrumentation in the chemistry laboratory,” Polavarapu explains. For this reason, he was also involved in the planning of the Nano-Institute from a very early stage, and the Institute’s Chemistry Laboratory was built according to his specifications. “Not only do we have more work space in the new laboratories, we also have more space for instruments, which is important for a pleasant environment for our research. In addition, we are much closer together. Previously, the Department’s facilities were located in different places. Our new labs are well connected each other,” he says. “That’s a great advantage when it comes to the interdisciplinary research work carried out in different laboratories (Chemistry and Optics) at the Chair.”

Dr. Polavarapu has been actively working on the shape-controlled synthesis of halide perovskite nanocrystals. “Working with nanocrystals is tremendously exciting, because they exhibit completely different properties compared to their bulk counterparts” he says. The properties of colloidal nanocrystals are extremely dependent on their size, shape and chemical composition. For instance, simply changing the dimensions of the crystals by a few nanometers is sufficient to change the color of the emitted luminescence,” he explains. The versatility of the technology makes perovskite nanocrystals of particular interest for use in LED-based applications, as LEDs made of the new materials promise to be more economical and more durable. Polavarapu collaborates with other members of the SolTech consortium to further explore the photovoltaic applications of perovskite nanocrystals prepared in the chemistry laboratory of the Nano-institute Munich. He strongly believes that the nanocrystal based perovskite solar cells exhibit greater stability. One major problem with halide perovskite-based devices is that they contain lead as an essential component. Polavarapu’s aim to reduce the amounts required for function and ultimately to replace it with a more environmentally benign constituent.

Dr. Polavarapu obtained PhD from the National University of Singapore and then he was a postdoctoral fellow in Spain before he joined the research group of Professor Jochen Feldmann in 2015 as a Humboldt Fellow. In the meantime, as Head of the chemistry laboratory, he is an indispensable member of the team at the Nano-Institute. He is particularly impressed by the foresight that went into the planning of the new building – specifically with an eye on potential future developments. As a result, not only does the Institute conform to the current state of the art, it also has the potential to accommodate other research areas in the future.

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