Lead sulfide (PbS) nanocrystals are chemically tunable,
high-extinction near-infrared absorbers and emitters, but, as synthesized, are
coated in long organic ligands and therefore form electrically insulating
films. Here, we optimize the interparticle ordering and particle density of
films treated with a series of short organic ligands. We find that the types
and densities of defects in the film depend on the chemical structure of the
binding headgroup, and the length and rigidity of
the ligand.
Electron microscope images of single PbS nanocrystals (left) and monolayers of PbS nanocrystals treated with formic acid at the liquid-air interface (top) or solid-air interface (bottom)
