This CAREER award supports research and education in computational and theoretical condensed matter and materials physics. The research part of this project focuses on the development and application of new computational tools to study the electronic properties of heterogeneous interfaces formed between molecules and solid substrates. Such interfaces find broad applications in energy conversion materials, such as photovoltaics that convert solar energy into electric current and photocatalytic materials that harvest solar light to drive chemical reactions. To understand and control these complex processes at a fundamental level, it is essential to accurately describe the electronic structure based on quantum mechanical simulations of the materials. Given the large system size and the accuracy needed to quantitatively understand the energy conversion mechanisms at heterogeneous interfaces, most conventional simulation methods are unfortunately either inefficient or inaccurate.
The objective of the research part of this project is to develop a suite of new computational schemes that are both accurate and efficient in the characterization of the electronic structure at heterogeneous molecule-substrate interfaces. These methods will significantly expand the scope of materials and interfaces that can be routinely modeled as compared to the current state of the art. The basic idea is to divide the interface into its smaller constituents or building blocks and then treat each component with high-level theory while considering it embedded in the environment of the others. Using this embedding approach, the team will quantitatively investigate how the electronic structure of each component of the interface is affected by the others, and how the electronic structure of the entire interface is different from those of the individual constituents. The team will apply the new computational approach to a few emerging systems of experimental significance, especially interfaces involving multiple light absorbers and interfaces featuring electronic and optical properties which differ considerably when measured in different directions. The research will lead to new insights into energy conversion mechanisms and the rational design of new energy materials.
The research activity is closely integrated with the education and outreach parts of this project. The PI will organize a summer camp annually for local high school students in the southeastern Michigan area, promoting the awareness of the importance of computation and its power in scientific research. The summer camp also addresses the diversity challenge in science, technology, engineering, and mathematics in the metropolitan Detroit area. Additionally, the PI will provide summer intern positions in his research group for local high school students and teachers, broadening the impact of the PI’s undertaking in educating the next generation of scientists beyond training graduate students. Furthermore, the PI will continue the development of a Computational Chemistry course at Wayne State University for both undergraduate and graduate students. The PI will continuously add course content based on his research expertise in materials chemistry and customize the topics to meet the research needs of the enrolled students. Moreover, the PI plans to organize mini-workshops on the basic use of mathematical software in the Chemistry Department at Wayne State University for both undergraduate and graduate students, offered twice a year, as an endeavor to mitigate the students’ common math anxiety in the learning of science courses.
This CAREER award supports research and education in computational and theoretical condensed matter and materials physics. The research part of this project focuses on the development and application of new computational methods to study the quasiparticle electronic structure and optical excitations at heterogeneous interfaces formed between molecules and solid substrates. Such interfaces are ubiquitous in nanoscale energy conversion applications, such as photovoltaics and photocatalysis. Although many-body perturbation theory such as the GW-BSE formalism (G is the Green’s function, W is the screened Coulomb interaction, and BSE stands for Bethe-Salpeter equation) provides a rigorous theoretical framework, first-principles calculations of large molecule-substrate interfaces are computationally expensive. Lack of efficient yet reliable computational schemes for large heterogeneous interfaces hinders fundamental understanding of the molecule-substrate interactions and interfacial charge dynamics.
The research part of this project aims to develop a suite of new tools, termed as “dielectric embedding GW-BSEâ€, to make such calculations practically affordable for large interfaces without sacrificing accuracy. The essential idea is to confine explicit GW-BSE calculations within each component of the interface while treating the effect of the others as a dielectric environment. This project will leverage the newly developed methods to study a few systems of experimental significance, including: (1) interfaces formed between monolayer transition-metal dichalcogenides (TMDs) and (metallo)phthalocyanines, where the gaps and excitons of both components as well as the valley pseudospin of the TMD substrates within the interface will be studied; (2) interfaces involving black phosphorus, where the anisotropy of the dielectric screening at such interfaces will be scrutinized; and (3) charge-transfer systems modulated by interfaces, such as molecular donor-acceptor pairs adsorbed on metal or semiconductor substrates and large organic adsorbates on bilayer TMDs featuring inter-layer charge-transfer excitons.
The research activity is closely integrated with the education and outreach parts of this project. The PI will organize a summer camp annually for local high school students in the southeastern Michigan area, promoting the awareness of the importance of computation and its power in scientific research. The summer camp also addresses the diversity challenge in science, technology, engineering, and mathematics in the metropolitan Detroit area. Additionally, the PI will provide summer intern positions in his research group for local high school students and teachers, broadening the impact of the PI’s undertaking in educating the next generation of scientists beyond training graduate students. Furthermore, the PI will continue the development of a Computational Chemistry course at Wayne State University for both undergraduate and graduate students. The PI will continuously add course content based on his research expertise in materials chemistry and customize the topics to meet the research needs of the enrolled students. Moreover, the PI plans to organize mini-workshops on Mathematica and WolframAlpha in the Chemistry Department at Wayne State University for both undergraduate and graduate students, offered twice a year, as an endeavor to mitigate the students’ common math anxiety in the learning of science courses.
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.
