Kinetics of Photoluminescence Decay of Colloidal Quantum Dots: Nonexponential Behavior and Detrapping of Charge Carriers

Understanding the physics behind the kinetics of photoluminescence (PL) decay of colloidal quantum dots (QDs) is of critical importance for the characterization and potential applications of these materials. The nonexponential decays typically observed present a challenge due to a lack of models for their description that are simultaneously physically meaningful and practical to use. In this work, a new function for the description of the whole PL decay curves of drop-cast films of CdSe/ZnS QDs at room temperature is proposed whose parameters have a straightforward physical meaning, accounting for the long-time tails of the decays and highlighting the role of detrapping of charge carriers. This function and the interpretation of the PL decay that it provides represent an alternative to the widespread assumption that Förster resonance energy transfer takes place in systems of densely packed nearly monodisperse colloidal QDs.