Unconventional line defects engineering in two-dimensional boron monolayers

Line defects (LDs) are a kind of lattice imperfection widely existing in two-dimensional materials, which may play a significant role in the properties of materials. Different from the negative effect of LDs for stability in most 2D materials, we have proposed a simple universal rule to construct stable 2D boron isomers based on the LDs engineering, where the self-assembled monolayers are unconventionally enhanced. Based on the self-assembly of LDs from ${\ensuremath{\beta}}_{12}$ and ${\ensuremath{\chi}}_{3}$ monolayers, we have found several boron monolayers with higher stability on the Ag (111) substrate than the experimental phases, and two monolayers in our prediction have been confirmed by the recent experiments. Notably, the mechanical response of the boron monolayers also can be enhanced by the LDs, indicating the potential application for advanced flexible electronic devices.