Laser Flash Photolysis of Colloidal Indium Phosphide Quantum Dots

Colloidal quantum dots of indium phosphide and indium phosphide with a thin zinc sulfide shell have been synthesized, which have spectral absorption maxima of exciton peaks at 584 and 603 nm, respectively. For these particles, the induced absorption relaxation kinetics were obtained by flash photolysis (in the time range from similar to 50 fs to 0.5 ns), and the luminescence decay kinetics after pulsed excitation were also measured (in the time range from similar to 0.1 to similar to 130 ns). A comparison of these kinetics in the region of their overlap showed that the transient absorption decays much more slowly than the luminescence. In accordance with the concepts available in the literature, this behavior can be explained by the fact that the hole formed as a result of excitation is captured by surface traps, thereby blocking radiative recombination but having almost no effect on the induced absorption, which is mainly due to the electron formed during excitation. The unshelled particles obtained in this study, having a lower fluorescence quantum yield, exhibit faster hole trapping.