  Two-dimensional (2D) materials are among the most promising candidates for
beyond-silicon electronic, optoelectronic and quantum computing applications.
Recently, their recognized importance sparked a push to discover and
characterize novel 2D materials. Within a few years, the number of
experimentally exfoliated or synthesized 2D materials went from a couple of
dozens to more than a hundred, with the number of theoretically predicted
compounds reaching a few thousands. In 2018 we first contributed to this effort
with the identification of 1825 compounds that are either easily (1036) or
potentially (789) exfoliable from experimentally known 3D compounds. Here, we
report on a major expansion of this 2D portfolio thanks to the extension of the
screening protocol to an additional experimental database (MPDS) as well as to
the updated versions of the two databases (ICSD and COD) used in our previous
work. This expansion has led to the discovery of additional 1252 unique
monolayers, bringing the total to 3077 compounds and, notably, almost doubling
the number of easily exfoliable materials (2004). Moreover, we optimized the
structural properties of all these monolayers and explored their electronic
structure with a particular emphasis on those rare large-bandgap 2D materials
that could be precious to isolate 2D field effect transistors channels.
Finally, for each material containing up to 6 atoms per unit cell, we
identified the best candidates to form commensurate heterostructures, balancing
requirements on the supercells size and minimal strain.
