CAREER: Controlling the Deformability of Quantum Dots Solids for Wearable NIR Optoelectronics

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Nontechnical Wearable electronics that emit and detect near-infrared (IR) light hold promise for affordable and non-invasive healthcare, including early detection of disease and light therapy. In order to adapt to the natural movements of the skin, materials must maintain their structural integrity and electronic properties while being deformed or stressed. Many materials active in the near-IR are rigid and brittle, and thus cannot be used for wearable devices. The discovery of new materials for near-IR electronics is hindered due to a lack of fundamental understanding of how they behave under stress or strain. This project directly addresses that challenge. The PI will synthesize and systematically investigate composites that combine the strong near-IR optical response of quantum dots with the attractive electronic and physical properties of organic semiconductors. Through seamless integration of these materials, the PI will control their interactions and investigate their mechanical, optical, and electronic behavior. The fundamental understanding of molecular interactions developed through this project will enable breakthroughs in flexible electronics for healthcare, soft robotics, and in other fields. The PI is committed to broadening participation in STEM through strengthening pathway for students from high school through postgraduate studies. Education efforts will engage high school students in learning about nanomaterials and nanotechnology. The PI will create a new undergraduate course with interactive STEM outreach, and host a summer undergraduate research intern, thereby fostering diversity, equity, and inclusion in STEM. Technical This project aims to better understand how colloidal quantum dot (CQD) solids respond to strain, by developing crucial structure-property relationships to reveal how the molecular-level chemical and structural interactions between CQD and conjugated polymers (CP) impact the mechanical, optical, and electronic properties of the resulting heterostructures, and importantly how these key properties respond to mechanical deformation. However, it is currently unclear how the molecular-level chemical and structural interactions between these two components impact the carrier transport and recombination process, their ability to deform, and, more critically, how the chemical, structural, and optoelectronic properties change under strain. This project develops critical fundamental understandings of the mechano-optoelectronic properties of the CQD-CP heterostructures by (1) investigating the chemical and structural interaction between CQD and CP and their impact on the charge carrier transport and recombination characteristics of the CQD-CP heterostructures with different interfacial chemistry; (2) understanding the changes of the key chemical, structural and optoelectronic properties under strain and elucidate the underlying mechanism. To achieve this, the research team will first utilize a unique ligands exchange strategy to construct CQD - CP heterostructures with controllable interfaces at the molecular level. The research team will then employ X-ray photoelectron and X-ray diffraction spectroscopy, transmission electron spectroscopy, steady and time-resolved optical spectroscopy, and electrical characterization, with and without applied strain, to provide insights into how structure, charge transport, and recombination are impacted by the interfacial chemistry, and how they change under strain. The research activities provide fundamental knowledge that is foundational toward the rational design of CQD-based wearable optoelectronics and unlock their potential in personal healthcare, and soft robotics. 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.