Identification of Semiconductor Nanocrystals with Bright Ground-State Excitons.
ACS Nano
; 2024 Jul 22.
Article
in En
| MEDLINE
| ID: mdl-39037050
ABSTRACT
While semiconductor nanocrystals provide versatile fluorescent materials for light-emitting devices, their brightness suffers from the "dark exciton"âan optically inactive electronic state into which nanocrystals relax before emitting. Recently, a theoretical mechanism, the Rashba effect, was discovered that can overcome this limitation by inverting the lowest-lying levels and creating a bright excitonic ground state. However, no methodology is available to systematically identify materials that exhibit this inversion, hindering the development of superbright nanocrystals and their devices. Here, based on a detailed understanding of the Rashba mechanism, we demonstrate a procedure that reveals previously unknown "bright-exciton" nanocrystals. We first define physical criteria to reduce over 500,000 known solids to 173 targets. Higher-level first-principles calculations then refine this list to 28 candidates. From these, we select five with high oscillator strength and develop effective-mass models to determine the nature of their lowest excitonic state. We confirm that four of the five solids yield bright ground-state excitons in nanocrystals. Thus, our results provide a badly needed roadmap for experimental investigation of bright-exciton nanomaterials.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
ACS Nano
Year:
2024
Document type:
Article
Affiliation country:
United States
Country of publication:
United States