Stable two-dimensional materials are promising nanoelectronic materials due to their relatively small form factor and the great variety of chemical and electronic structure of 2D materials, allowing for the design of light-weight and low-cost materials for opto-electronic devices such as transistors, solar cells, and lasers. Here, we utilize first-principles theory to investigate the optoelectronic function of these monolayer materials, emphasizing the role of defects and electron-phonon interactions; two phenomena that will be present in and can domminate the properties of real materials.<br/><br/>For the recently synthesized 2D boron (borophene), we utilize density functional theory and density functional perturbation theory to understand the electron conductivity, optical transparency and plasmon resonances of a freestanding monolayer, as well as the monolayer on a Ag(111) substrate. Furthermore, we demonstrate that strains consistent with change in substrate can be utilized to modify the optoelectronic properties of borophene, suggesting that modification of growth conditions can be used to tune these properties.<br/><br/>Additionally, we employ first-principles many-body perturbation theory within the GW/BSE approximation to investigate the influence of point defects on the opto-electronic properties of a monolayer semiconductor composed of GeSe. We systematically study a series of charged vacancies, their trap state energies, and their impact on optical absorption. We determine that the excitonic properties of the material are significantly affected by the presence of defects, with implications for devices fabricated using this material system.

Excited-state properties of imperfect 2D materials: Impact of defects and temperature from first principles

2019 Fall National Meeting

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