  Very recently, borophene has been attracting extensive and ongoing interest
as the new wonder material with structural polymorphism and superior
attributes, showing that the structural imperfection of line defects (LDs)
occurs widely at the interface between $\nu_{1/5}$ ($\chi_3$) and $\nu_{1/6}$
($\beta_{12}$) boron sheets. Motivated by these experiments, here we present a
theoretical study of electron transport through two-terminal disordered
borophene nanoribbons (BNRs) with random distribution of LDs. Our results
indicate that LDs could strongly affect the electron transport properties of
BNRs. In the absence of LDs, both $\nu_{1/5}$ and $\nu_{1/6}$ BNRs exhibit
metallic behavior, in agreement with experiments. While in the presence of LDs,
the overall electron transport ability is dramatically decreased, but some
resonant peaks of conductance quantum can be found in the transmission spectrum
of any disordered BNR with arbitrary arrangement of LDs. These disordered BNRs
exhibit metal-insulator transition by varying nanoribbon width with tunable
transmission gap in the insulating regime. Furthermore, the bond currents
present fringe patterns and two evolution phenomena of resonant peaks are
revealed for disordered BNRs with different widths. These results may help for
understanding structure-property relationships and designing LD-based
nanodevices.
