Foundational Synthesis and Structure-Optical Property Relations of Linear Quantum Dot Heterostructures

Nontechnical Description Quantum dots are tiny semiconductor particles with optical and electronic properties that can be tuned by changing their size. Q-dots have already enabled important technologies such as vivid, bright and efficient flat panel displays. Control over their shape and how they form nanostructures could open new ways of tailoring their properties for innovative uses. This project seeks to develop a new class of materials consisting of quantum dots, each with independently tuned size, shape, and composition. Through exquisite control over their characteristics, researchers will elucidate how these materials interact with light and electricity and how those interaction can be controlled. This empowering knowledge can accelerate the design and customization of complex materials for emerging technologies in communications, sensing, energy, and more. The challenges to be tackled in this interdisciplinary project will provide ample educational and training opportunities for participants. Results from this project will be incorporated into lectures and laboratory courses for graduate and undergraduate students. The PI will also host tours for K-12 students to stimulate their imagination and promote public interest in science and technology. Technical Description The successful application of colloidal quantum dots (QDs) in technologies such as displays has largely been enabled by the improvements in performance and stability afforded by the growth of heterostructures. The introduction of anisotropic shapes to these materials is now broadening the engineering space for tailoring properties that could lead to transformative advances in multiple areas. This project aims to establish the fundamental knowledge necessary to develop deterministic and robust routes to synthesize complex heterostructures based on colloidal QDs. The focus here is on solution growth of linear QD heterostructures, the simplest of anisotropic shapes. Through systematic studies examining thermodynamics of interfaces and kinetic barriers to growth, this project will elucidate how these factors impact regioselectivity, size/shape, and directionality of heterogeneous nucleation and growth. This knowledge will then allow precision in unidirectional growth of QD heterostructures with independently variable diameter, length, and composition for each segment. These QD heterostructures represent a new class of tunable materials and will allow the exploration of how key structural parameters, which can be varied systematically, determine their optical and electronic properties. This foundational knowledge should accelerate the design and implementation of complex nanoscale materials that can be tailored on demand for a wide range of applications from imaging, photovoltaics, and optoelectronics to quantum photonic technologies. 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.