SURFACE EFFECTS ON THE OPTICAL-PROPERTIES OF CADMIUM SELENIDE QUANTUM DOTS

Cadmium selenide quantum dots were synthesized with different functional groups attached to their surfaces. The effect of surface chemistry on the optical properties was determined through optical hole-burning and luminescence measurements. Nanosecond hole burning probed ground-state recovery due to recombination at trap states, and the results indicate that nanocrystallites with better surface passivation and stronger bonds to terminating ligands have longer ground-state recovery times. Better surface passivation and stronger bond strength were also correlated with increased luminescence intensity, which shows the relative amount of radiative recombination. The luminescence spectrum changed very little as a function of the terminating ligand, indicating little or no excitation transfer from the crystallite to the ligand for these samples.