Understanding Quantum Effects in 2D polymeric Systems
Abstract
Overview and Merit: Two-dimensional polymers (2DPs) consist of covalently bonded molecular tiles (ligands) that extend across two dimensions to form layered van der Waals (vdW) materials similar to graphene and other 2D inorganic materials (MoS2, WSe2, h-BN, etc.). While quantum effects are well-established for inorganic vdW solids, properties of 2DPs remain largely unknown. This is mainly due to difficulties in 2DPs sample preparation, characterization, as well as instrumentation inadequacies. Thus, studies are often restricted to simulations or thick polymers. However, true merits of 2DPs lie in two-dimensions when quantum effects become prominent. For example, theoretical studies predict and our preliminary experimental findings hint many exciting properties and quantum phenomena on 2DPs at the nanoscale. Precisely focused on these merits, the scientific objective of this Short Term Innovative Research (STIR) project is to enable, discover, and understand emergent optical and electronic behavior of optically active 2DPs. The novelty of the approach in this research effort is three-folds: 1) We have identified and synthesized optically and electronically active 2DPs using octaaminonaphthalene (OAN) and hexaaminobenzene (HAB) monomers. Our preliminary predictions and experimental findings point towards exciting properties relevant to DoD. These properties include high carrier mobility, presence of direct band gap from IR to UV, and optical activity (strong light-matter interactions) that are not observed in other 2DPs. 2) In past, the lateral sizes of 2DPs could only reach up to 100nm-1um which largely limited their characterization. 3) Non-destructive structural, electrical, and optical characterization of these soft materials are only enabled by cryogenic-TEM, nano-EELS, and nm-spatial resolution optical techniques available to us. The project will systematically investigate material behavior of 2DPs from bulk to monolayers to capture quantum confinement effects. Studies will help to test theoretical predictions and unravel novel quantum phenomena at nanoscale. If successful, this research effort will 1) offer the first look at electronic, optical properties of 2DPs, 2) provide atomic resolution insight into crystallographic properties of 2DPs, and 3) establish how material behavior of 2DPs changes when quantum size confinement effects become dominant. Impact: Considering the technological and practical impact that traditional polymers have had to date, 2DPs are anticipated to lead to a wide range of new applications e.g., semiconductors, organic electronics, communication technologies, and separation membranes. Within this STIR proposal, accessing the quantum confinement limit on these highly attractive OAN and HAB based 2DPs, testing theoretically predicted novel effects, and the quantum effects to be discovered, and understood will push the boundary of materials behavior beyond its current limitations. These material systems have been predicted to have high-carrier mobilities, exhibit direct gap values in IR to UV energy ranges, and have strong light emission and absorption characteristics. As such, they have the potential to make transformative impact in new generation IR, electronic, and optical communication technologies for military applications. In addition, entirely new applications in nanoelectronics, photonics, and energy conversion/storage are also expected. Of which, the details and defense impact can only be appreciated after the results of this proposed effort are brought to light. This experimental effort pioneers a new material system and associated science that is exciting but also high-risk as it is largely an uncharted research exploration. However, in light of the DoDÕs continued efforts to seek new materials with unique properties for advanced military applications, the potential outcome of this proposed research significantly outweighs the associated risk.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810381
Entities
People
- Sefaattin Tongay
Organizations
- Arizona State University
- Army Contracting Command
- United States Army