Photophysics of Charged CdSe Quantum Dots

Spectroscopic properties of CdSe quantum dots (QDs) have been extensively explored in the last decade. Charged QDs are expected to show different spectroscopic behaviors from uncharged ones. That is, a charged QD is believed to be 'dark', as the free charge quenches the photoluminescence (PL) through non-radiative Auger processes. This model has been applied to explain both photodarkening effects observed in QD glasses and PL intermittency observed in single QDs. Furthermore, absorption of the 1S_e states is expected to bleach as well. We report a thin film device that can electrically inject carriers into CdSe QDs causing reversible quenching of the PL and absorption.