3 research outputs found
Polarised Photoluminescence from Surface-Passivated PbS Nanocrystals
Effective surface-passivation of PbS nanocrystals in aqueous colloidal
solution has been achieved following treatment with CdS precursors. The
resultant photoluminescent emission displays two distinct components, one
originating from the absorption band-edge and the other from above the
absorption band-edge. We show that both of these components are strongly
polarised but display distinctly different behaviours. The polarisation arising
from the band-edge shows little dependence on the excitation energy while the
polarisation of the above-band-edge component is strongly dependent on the
excitation energy. In addition, time resolved polarisation spectroscopy reveals
that the above-band-edge polarisation is restricted to the first couple of
nanoseconds, while the band-edge polarisation is nearly constant over hundreds
of nanoseconds. We recognise an incompatibility between the two different
polarisation behaviours, which enables us to identify two distinct types of
surface-passivated PbS nanocrystal.Comment: Preprint, 19 pages, 4 figure