Two-band optical gain and ultrabright electroluminescence from colloidal quantum dots at 1000 A cm<sup>-2</sup>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35768407.
- Also identified by DOI 10.1038/s41467-022-31189-4 and PMC identifier 9243032.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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<sup>-2</sup>) and brightness (~10 million cd m<sup>-2</sup>), 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.