Two-Dimensional Materials with Giant Optical Nonlinearities near the Theoretical Upper Limit.
basic_science · Level V
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- Record sourced from PubMed, PMID 33724766.
- Also identified by DOI 10.1021/acsnano.1c00344.
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Abstract
Nonlinear optical (NLO) phenomena such as harmonic generation and Kerr and Pockels effects are of great technological importance for lasers, frequency converters, modulators, switches, <i>etc</i>. Recently, two-dimensional (2D) materials have drawn significant attention due to their strong and peculiar NLO properties. Here, we describe an efficient first-principles workflow for calculating the quadratic optical response and apply it to 375 non-centrosymmetric semiconductor monolayers from the Computational 2D Materials Database (C2DB). Sorting the nonresonant nonlinearities with respect to bandgap <i>E</i><sub>g</sub> reveals an upper limit proportional to <i>E</i><sub><i>g</i></sub><sup>-4</sup>, which is neatly explained by two distinct generic models. We identify multiple promising candidates with giant nonlinearities and bandgaps ranging from 0.4 to 5 eV, some of which approach the theoretical upper limit and greatly outperform known materials. Our comprehensive library of <i>ab initio</i> NLO spectra for all 375 monolayers is freely available <i>via</i> the C2DB Web site.