Abstract:
The kinetics of luminescence decay of nanocrystals (NC) contains important information about the excited states of NC, the type and number of traps of charge carriers (electrons, holes) or excitation-energy acceptors (molecules, other closely located NC), the distribution of traps by energy, and the mechanism of electron excitation-energy transfer from NC to acceptors. Usually, the kinetics of NC luminescence decay is non-exponential and is approximated with good accuracy by the sum of two or three exponentials. In recent years, it has been experimentally observeg that after pulsed excitation, the luminescence intensity of an ensemble of NCs decreases at large times according to a power law. To explain this regularity, a new model of the NC ensemble and a corresponding new function for approximating the kinetics of luminescence decay are proposed. The basis for obtaining this function are the balance equations and assumptions about the exponential distribution of traps by energies and about the reversible return of charge carriers from traps to NC. Approximation of experimental data by the proposed function will allow to estimate the rate of capture of charge carriers by traps and the parameters of the distribution function of traps by energies.
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