Actively Controlled Purcell Enhancement of Colloidal Quantum Dots in Gated Plasmonic Heterostructures

Controlling light emission of quantum emitters, such as semiconductor quantum dots, is a central theme of nanotechnology. Typically, the emitted power from an array of quantum emitters is modulated by changing the optical or electrical pump intensity, within a given nanostructured environment. We propose and demonstrate a conceptually different approach to dynamically control the power radiated by the emitter. We experimentally demonstrate the modulation of the radiative emission rate, the emitted power, and the quantum efficiency, at constant optical pump intensity, via dynamical changes to the local density states. The local density of states is modulated by changing the carrier density, under field effect gate control, in a plasmonic titanium nitride layer nearby the emitters. Our proof-of-principle experiment, which uses a TiN/SiO₂/Ag plasmonic heterostructure, demonstrates a new active plasmonic mechanism for modulating visible light emission that is extensible to other type of quantum emitters. Moreover, it also may pave a path towards ultrathin LCD-free displays with long durability, reduced pixel size and large viewing angle.