
16 Biosensors Based on Nanomaterials and Nanodevices
NIR-emitting QDs are lead chalcogenide QDs, which include PbS, PbSe, and PbTe, with
emission wavelength tuned over a broad NIR wavelength range [8,34,35].
An extremely promising type of QDs, derived from the aforementioned simple struc-
tures, are core-shell QDs, which consist of core QDs covered by the shell of a different
semiconductor material. Depending on the relative alignment of conduction- and valence-
band edges of core and shell semiconductors, the core-shell heterostructure can be denom-
inated as type-I, reverse type-I, and type-II (Figure 2.4a) [41–45]. In the type-I structure,
the ...