Investigating the effects of thermal-opto-mechanical interactions on optical responses of multilayer semiconductor nanocrystals

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This project will investigate the optical characteristics of multilayer semiconductor nanocrystals under different thermal environments and mechanical stresses. Semiconductor nanocrystals are nanoscale crystalline particles with physical and optical properties that are tunable through controlling their size and geometric shape. This project will study the characteristics of multilayer semiconductor nanocrystals made from cadmium selenide, cadmium sulphide and zinc sulphide, which are synthesized in a microreactor system. A comprehensive understanding of the thermal-opto-mechanical properties in these multilayer semiconductor nanocrystals can lead to the development of nanocrystal-based devices and systems, as well as better design approaches for their applications in optomechanical devices and systems, nanophotonics, and biosensors, such as white light-emitting diodes. The results from this research will help strengthen U.S. standing and influence in nanoelectronics, solar energy and nanophotonics. The interdisciplinary nature of this research will help the American workforce become more competitive in both materials processing and photonics through the training of graduate and undergraduate students. These students will master the synthesis and characterization skills of semiconductor nanocrystals and will develop the skills for solving technical problems. The investigator will actively recruit women and underrepresented minorities in order to promote their inclusion in the fields of nanophotonics and biophotonics.Semiconductor nanocrystals as potential building blocks of nanophotonics and biophotonics have attracted great interest in a variety of applications. The comprehensive understanding of the effects of the geometric dimensions and thermal-opto-mechanical interactions on the optical characteristics of the multilayer semiconductor nanocrystals can help develop better performing and more reliable nanocrystal-devices and systems. This research project will investigate the optical characteristics of the multilayer semiconductor nanocrystals under thermomechanical loading, including tension, compression and cyclic heating-cooling via a closely coupled experimental and modeling approach, and the dependence of the geometrical dimensions of the multilayer semiconductor nanocrystals on the precursor concentrations, temperature and residence time. A microreactor in a microfluidic system will be developed to synthesize the multilayer semiconductor nanocrystals and to investigate the rate mechanisms controlling the growth of the multilayer semiconductor nanocrystals in a flow environment. The research team will establish correlations between optical properties of the multilayer semiconductor nanocrystals, stress, and temperature as well as the geometrical dimensions. The team will develop numerical models that can quantitatively analyze optical responses of nanocrystals under thermomechanical loading. These relationships provide fundamental understanding of the thermal-opto-mechanical coupling in semiconductor nanocrystals and can provide guidelines to better design nanocrystal-based devices and systems with high performance and reliability. Students will be trained on the design of microfluidic reactors and the development of the techniques for local characterization of thermal-opto-mechanical behavior of semiconductor nanocrystals. A design project of developing microfluidic systems for chemical reactions will be developed and offered to high school and undergraduate students, from which students can learn both the technical and nontechnical requirements for the design of a useful product.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.