Abstract
Emission control of colloidal quantum dots (QDs) is a cornerstone of modern high-quality lighting and display technologies. Dynamic emission control of colloidal QDs in an optoelectronic device is usually achieved by changing the optical pump intensity or injection current density. Here we propose and demonstrate a distinctly different mechanism for the temporal modulation of QD emission intensity at constant optical pumping rate. Our mechanism is based on the electrically controlled modulation of the local density of optical states (LDOS) at the position of the QDs, resulting in the modulation of the QD spontaneous emission rate, far-field emission intensity, and quantum yield. We manipulate the LDOS via field effect-induced optical permittivity modulation of an ultrathin titanium nitride (TiN) film, which is incorporated in a gated TiN/SiO2/Ag plasmonic heterostructure. The demonstrated electrical control of the colloidal QD emission provides a new approach for modulating intensity of light in displays and other optoelectronics.
Highlights
Emission control of colloidal quantum dots (QDs) is a cornerstone of modern high-quality lighting and display technologies
We use InP/ZnS core–shell colloidal QDs, which are of greater application interest because they are free of heavy metals and may be beneficial in considering health and environmental concerns
This results in a modulation of the complex refractive index of titanium nitride (TiN) and, modulation of the local density of optical states (LDOS) at the position of QDs embedded in the SiO2 layer
Summary
Emission control of colloidal quantum dots (QDs) is a cornerstone of modern high-quality lighting and display technologies. The spontaneous emission decay rate of a solid state emitter can be modified by coupling the emitter to a nanostructured environment with a tailored local density of optical states (LDOS)[2,3]. This phenomenon, known as the Purcell effect, has yielded a 540-fold increase of the emission decay rate and a simultaneous 1900-fold increase of total emission intensity for colloidal QDs coupled to a plasmonic nanocavity[4]. Our proof-of-principle experiment demonstrates an active plasmonic mechanism for modulating visible light that is extensible to other types of quantum emitters
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