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Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm^-2.

ABSTRACT: Colloidal quantum dots (QDs) are attractive materials for the realization of solution-processable laser diodes. Primary challenges towards this objective are fast optical-gain relaxation due to nonradiative Auger recombination and poor stability of colloidal QD solids under high current densities required to obtain optical gain. Here we resolve these challenges and achieve broad-band optical gain spanning the band-edge (1S) and the higher-energy (1P) transitions. This demonstration is enabled by continuously graded QDs with strongly suppressed Auger recombination and a current-focusing device design, combined with short-pulse pumping. Using this approach, we achieve ultra-high current densities (~1000 A cm^-2) and brightness (~10 million cd m^-2), and demonstrate an unusual two-band electroluminescence regime for which the 1P band is more intense than the 1S feature. This implies the realization of extremely large QD occupancies of up to ~8 excitons per-dot, which corresponds to complete filling of the 1S and 1P electron shells.

SUBMITTER: Jung H

PROVIDER: S-EPMC9243032 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Publications

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm<sup>-2</sup>.

Jung Heeyoung H Park Young-Shin YS Ahn Namyoung N Lim Jaehoon J Fedin Igor I Livache Clément C Klimov Victor I VI

Nature communications 20220629 1

Colloidal quantum dots (QDs) are attractive materials for the realization of solution-processable laser diodes. Primary challenges towards this objective are fast optical-gain relaxation due to nonradiative Auger recombination and poor stability of colloidal QD solids under high current densities required to obtain optical gain. Here we resolve these challenges and achieve broad-band optical gain spanning the band-edge (1S) and the higher-energy (1P) transitions. This demonstration is enabled by ...[more]

PMID: 35768407

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Project description:Pairs of coupled quantum dots with controlled coupling between the two potential wells serve as an extremely rich system, exhibiting a plethora of optical phenomena that do not exist in each of the isolated constituent dots. Over the past decade, coupled quantum systems have been under extensive study in the context of epitaxially grown quantum dots (QDs), but only a handful of examples have been reported with colloidal QDs. This is mostly due to the difficulties in controllably growing nanoparticles that encapsulate within them two dots separated by an energetic barrier via colloidal synthesis methods. Recent advances in colloidal synthesis methods have enabled the first clear demonstrations of colloidal double quantum dots and allowed for the first exploratory studies into their optical properties. Nevertheless, colloidal double QDs can offer an extended level of structural manipulation that allows not only for a broader range of materials to be used as compared with epitaxially grown counterparts but also for more complex control over the coupling mechanisms and coupling strength between two spatially separated quantum dots. The photophysics of these nanostructures is governed by the balance between two coupling mechanisms. The first is via dipole-dipole interactions between the two constituent components, leading to energy transfer between them. The second is associated with overlap of excited carrier wave functions, leading to charge transfer and multicarrier interactions between the two components. The magnitude of the coupling between the two subcomponents is determined by the detailed potential landscape within the nanocrystals (NCs). One of the hallmarks of double QDs is the observation of dual-color emission from a single nanoparticle, which allows for detailed spectroscopy of their properties down to the single particle level. Furthermore, rational design of the two coupled subsystems enables one to tune the emission statistics from single photon emission to classical emission. Dual emission also provides these NCs with more advanced functionalities than the isolated components. The ability to better tailor the emission spectrum can be advantageous for color designed LEDs in lighting and display applications. The different response of the two emission colors to external stimuli enables ratiometric sensing. Control over hot carrier dynamics within such structures allows for photoluminescence upconversion. This Account first provides a description of the main hurdles toward the synthesis of colloidal double QDs and an overview of the growing library of synthetic pathways toward constructing them. The main discoveries regarding their photophysical properties are then described in detail, followed by an overview of potential applications taking advantage of the double-dot structure. Finally, a perspective and outlook for their future development is provided.

Dataset Information

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm^-2.

Publications

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm<sup>-2</sup>.

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Dataset Information

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm-2.

Publications

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm<sup>-2</sup>.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm^-2.