Electrical control of single-photon emission in highly charged individual colloidal quantum dots

Abstract

Electron transfer to an individual quantum dot promotes the formation of charged excitons with enhanced recombination pathways and reduced lifetimes. Excitons with only one or two extra charges have been observed and exploited for very efficient lasing or single–quantum dot light-emitting diodes. Here, by room-temperature time-resolved experiments on individual giant-shell CdSe/CdS quantum dots, we show the electrochemical formation of highly charged excitons containing more than 12 electrons and 1 hole. We report the control over intensity blinking, along with a deterministic manipulation of quantum dot photodynamics, with an observed 210-fold increase in the decay rate, accompanied by 12-fold decrease in the emission intensity, while preserving single-photon emission characteristics. These results pave the way for deterministic control over the charge state, and room-temperature decay rate engineering for colloidal quantum dot–based classical and quantum communication technologies.

Purifying single photon emission from giant shell CdSe/CdS quantum dots at room temperature

“…2d) deviate from singleexponential decays and both of them contain a short and long decay components. In the low pump fluency case (pink curve), the short decay component does not originate from the multiexciton emission, as its contribution is negligible, thus we assign it to the trion emission visible in the blinking dynamics [24,25]. At the saturating pump fluency (blue in Fig.…”

“…We assign the intensity response at low pump fluency (Fig. 2a) to the blinking primarily between neutral and positively charged excitons [24,25]. The flickering at high pump fluency (Fig.…”

“…Multi-excitons are characterized by short radiative lifetimes as the Auger-related non-radiative relaxation rate grows quadratically with the number of charges [21,24]. The decay histograms measured at the low and saturating pump fluency (Fig.…”

Laser Writing of Color Centers

“…Compared to probabilistic entangled photon pairs generated by spontaneous parametric down-conversion, [21][22][23][24] solid-state SPE can be electrically and optically excited and fabricated deterministically with scalability. [25][26][27][28][29][30] Recently, color centers in various materials have been developed for photonic integration with other components, such as waveguides, [31][32][33] and resonators. [34][35][36][37][38] Taking advantage of their unique spin or single-photon emission characteristics, quantum devices, such as single-photon level quantum-optical switching, [39] and quantum memory have been proposed.…”

Room‐Temperature Low‐Voltage Control of Excitonic Emission in Transition Metal Dichalcogenide Monolayers

“…Manipulation of excitons via charge injection enables numerous optoelectronic functionalities, including sub‐exciton lasing in quantum dots, [ 1 ] single‐photon generation from light‐emitting diodes (LEDs), [ 2 ] control of photoluminescence blinking, [ 3 ] and tuning photon emission lifetimes. [ 4 ] Similar doping techniques have been applied to control the charge state in atomically thin materials; in particular, to tune the zero‐phonon line in hexagonal boron nitride (hBN), [ 5 ] to electrically drive single‐photon emission in tungsten diselenide (WSe 2 ) and tungsten disulfide (WS 2 ), [ 6 ] and to harness electroluminescence from multi‐particle exciton complexes in WSe 2 and WS 2 , [ 7 ] and other TMD‐based LEDs with unique properties. [ 8 ]…”