skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Ultrasmall HgTe Quantum Dots with Near-Unity Photoluminescent Quantum Yields in the Near and Shortwave Infrared
We demonstrate a low-temperature synthesis of ultrasmall (<2 nm) HgTe quantum dots (QDs) with superlative optical properties in the near and shortwave infrared. The tunable cold-injection synthesis produces HgTe QDs ranging from 1.7 to 2.3 nm in diameter, with photoluminescence maxima ranging from 900 to 1180 nm and a full-width at half-maximum of ∼100 nm (∼130 meV). The synthesized quantum dots display high photoluminescence quantum yields (PLQY) ranging from 80 to 95% based on both relative and absolute methods. Furthermore, samples retain their high PLQY (∼60%) in the solid state, allowing for first-of-their-kind photoluminescence imaging and blinking studies of HgTe QDs. The facile synthesis allows for the isolation of small, photostable HgTe quantum dots, which can provide valuable insight into the extremes of quantum confinement.  more » « less
Award ID(s):
1945572
PAR ID:
10572878
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
Chemistry of Materials
Volume:
36
Issue:
15
ISSN:
0897-4756
Page Range / eLocation ID:
7561 to 7569
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, ACS Energy Letters)
    Direct optical lithography presents a promising patterning method for colloidal quantum dots (QDs). However, additional care needs to be taken to prevent deterioration of the optical properties of QDs upon patterning, especially for InP-based QDs. This study proposes an efficient method for high-resolution patterning of InP-based QDs using a photoacid generator while preserving their optical properties. Specifically, our solid-state ligand exchange strategy, replacing chloride ligands with long-chain amine/carboxylate pair ligands, successfully recovered the photoluminescence quantum yield (PLQY) of the patterned InP-based QD films to ∼67% of the original PLQY. Upon examination of the origins of the PLQY reduction during patterning, we concluded that the formation of deep traps caused by the exchanged chloride ligands was the primary cause. Finally, we fabricated high-resolution (feature size: 1 μm), multicolored patterns of InP-based QDs, thereby demonstrating the potential of the proposed patterning method for next-generation high-resolution displays and optoelectronic devices. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Energy Materials)
    Abstract Metal cation‐doped lead halide perovskite (LHP) quantum dots (QDs) with photoluminescence quantum yields (PLQYs) higher than unity, due to quantum cutting phenomena, are an important building block of the next‐generation renewable energy technologies. However, synthetic route exploration and development of the highest‐performing QDs for device applications remain challenging. In this work, Smart Dope is presented, which is a self‐driving fluidic lab (SDFL), for the accelerated synthesis space exploration and autonomous optimization of LHP QDs. Specifically, the multi‐cation doping of CsPbCl3QDs using a one‐pot high‐temperature synthesis chemistry is reported. Smart Dope continuously synthesizes multi‐cation‐doped CsPbCl3QDs using a high‐pressure gas‐liquid segmented flow format to enable continuous experimentation with minimal experimental noise at reaction temperatures up to 255°C. Smart Dope offers multiple functionalities, including accelerated mechanistic studies through digital twin QD synthesis modeling, closed‐loop autonomous optimization for accelerated QD synthetic route discovery, and on‐demand continuous manufacturing of high‐performing QDs. Through these developments, Smart Dope autonomously identifies the optimal synthetic route of Mn‐Yb co‐doped CsPbCl3QDs with a PLQY of 158%, which is the highest reported value for this class of QDs to date. Smart Dope illustrates the power of SDFLs in accelerating the discovery and development of emerging advanced energy materials. 
    more » « less
  3. ; ; ; ; ; (, Reaction Chemistry & Engineering)
    null (Ed.)
    The multistep and continuous production of core–shell III–V semiconductor nanocrystals remains a technological challenge. We present a newly designed high-temperature and miniature continuous stirred-tank reactor cascade, for the continuous and scalable synthesis of InP/ZnS core–shell quantum dots with a safer aminophosphine precursor comparing to standard protocols involving (TMS) 3 P . The resulting InP/ZnS QDs exhibit emissions between 520 and 610 nm, narrow emission linewidths in the range of 46–64 nm and photoluminescence quantum yields up to 42%. 
    more » « less
  4. ; ; (, MRS Advances)
    Abstract The actual incorporation of dopant species into the ZnS Quantum Dots (QDs) host lattice will induce structural defects evidenced by a red shift in the corresponding exciton. The doping should create new intermediate energetic levels between the valence and conduction bands of the ZnS and affect the electron-hole recombination. These trap states would favour the energy transfer processes involved with the generation of cytotoxic radicals, so-called Reactive Oxygen Species, opening the possibility to apply these nanomaterials in cancer research. Any synthesis approach should consider the direct formation of the QDs in biocompatible medium. Accordingly, the present work addresses the microwave-assisted aqueous synthesis of pure and doped ZnS QDs. As-synthesized quantum dots were fully characterized on a structural, morphological and optical viewpoint. UV-Vis analyzes evidenced the excitonic peaks at approximately 310 nm, 314 nm and 315 nm for ZnS, Cu-ZnS and Mn-ZnS, respectively, Cu/Zn and Mn/Zn molar ratio was 0.05%. This indicates the actual incorporation of the dopant species into the host lattice. In addition, the Photoluminescence spectrum of non-doped ZnS nanoparticles showed a high emission peak that was red shifted when Mn 2+ or Cu 2+ were added during the synthesis process. The main emission peak of non-doped ZnS, Cu-doped ZnS and Mn-doped ZnS were observed at 438 nm, 487 nm and 521 nm, respectively. Forthcoming work will address the capacity of pure and Cu-, Mn-ZnS quantum dots to generate cytotoxic Reactive Oxygen Species for cancer treatment applications. 
    more » « less
  5. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Functional Materials)
    Abstract All‐inorganic CsPbI3quantum dots (QDs) have shown great potential in photovoltaic applications. However, their performance has been limited by defects and phase stability. Herein, an anion/cation synergy strategy to improve the structural stability of CsPbI3QDs and reduce the pivotal iodine vacancy (VI) defect states is proposed. The Zn‐doped CsPbI3(Zn:CsPbI3) QDs have been successfully synthesized employing ZnI2as the dopant to provide Zn2+and extra I−. Theoretical calculations and experimental results demonstrate that the Zn:CsPbI3QDs show better thermodynamic stability and higher photoluminescence quantum yield (PLQY) compared to the pristine CsPbI3QDs. The doping of Zn in CsPbI3QDs increases the formation energy and Goldschmidt tolerance factor, thereby improving the thermodynamic stability. The additional I−helps to reduce theVIdefects during the synthesis of CsPbI3QDs, resulting in the higher PLQY. More importantly, the synergistic effect of Zn2+and I−in CsPbI3QDs can prevent the iodine loss during the fabrication of CsPbI3QD film, inhibiting the formation of newVIdefect states in the construction of solar cells. Consequently, the anion/cation synergy strategy affords the CsPbI3quantum dot solar cells (QDSC) a power conversion efficiency over 16%, which is among the best efficiencies for perovskite QDSCs. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email