Carrier recombination in CdS nanocrystals under single-electron and high-density excitation

Abstract

Room-temperature green luminescence has been studied in laser-modified (darkened) CdS nanocrystals with the average radii B ranging above the exciton Bohr radius (from 3.3 nm to 100 nm). Under high picosecond-pulse excitation, the electron-hole plasma decay kinetics exhibited adecrease of lifetime with decreasing crystallite size, enabling the surface recombination with the velocity of 1.3 x lo3 cm s-' to be revealed. Under low cw excitation, a striking increase in the luminescence intensity of nanocrystals with one excited electron-hole pair was discovered for average radii below 10 nm. The bulk-like bimolecular recombination with the constant of 3 x 10"0cm3s-' was shown to account for the observed size dependence.

An investigation of semiconductor nanoparticles for application to all-optical switching

“…This generalized result is seen in the literature [22] . For this case, with small , the decay coefficient is Γ ≈ 1 and the cardinal sine term in Eq.…”

Nucleotide-stabilized cadmium sulfide nanoparticles

“…Reports on the synthesis of nucleic acid-templated nanoparticles have yielded preliminary information concerning how these biomolecules can be used as ligands. [6][7][8][9][10][11] However, a comprehensive understanding of how nucleic acids function in semiconductor nanocrystal synthesis has not been attained.…”

Ultrafast Charge-Carrier Dynamics of Copper Oxide Nanocrystals

“…The long duration of this process matches typical time constants seen for trap-assisted charge-carrier recombination in semiconductor nanocrystals. 41,49,51 The authors note that the associated weighting of the third time constant's term, denoted by , is positive, which indicates that the observed response is dominated by state-filling-induced bleaching of transitions from the VB up to mid-gap states. This is in contrast to free-carrier absorption, which would induce a negative change in transmission.…”