Results and discussion
Characterization of the synthesized Cys-CdS QDs
The water-soluble cysteamine-modified CdS QDs (Cys-CdS QDs)
were synthesized by a simple one-pot method. The optical properties
of the synthesized QDs were characterized, and the results are
shown in Fig. 1. The synthesized Cys-CdS QDs exhibited a first excitonic
absorption at 425 nm and an emission maximum at 525 nm
upon excitation at 360 nm. The synthesized Cys-CdS QDs showed a
narrow and symmetrical emission spectrum, suggesting that the
Cys-CdS QDs are nearly homogeneous and monodisperse [27].
The fluorescence emission spectrum did not exhibit a tail at longer
wavelengths, indicating the absence of surface energy traps [28].
Furthermore, the morphology of Cys-CdS QDs was examined by
transmission electron microscopy (TEM), as shown in Fig. S1 (ESI).