In situ characterizations of charge injection dynamics, equilibrated concentration, and electric field distributions shed light on the critical mechanisms of quantum dot light-emitting diodes (QD-LEDs). In this work, we developed electrically excited transient absorption spectroscopy, which can provide the above key information, to investigate the efficiency roll-off of QD-LEDs. We found that the average electron populations per QD are low when QD-LEDs exhibit efficiency roll-off, excluding Auger recombination as the main cause. We also revealed that the weak electrical field inside the QD layer under forward biases has a negligible impact on the efficiency. Interestingly, we found that as the voltage increases the electron concentration in the QD layer saturates at very low levels. When combined with the concomitant efficiency roll-off, we propose electron leakage is the main loss at elevated driving voltages. We further demonstrate that increasing the electron confinement potential with the ZnS shell enables us to efficiently mitigate the efficiency roll-off.

Copper indium selenide (CISe) is a prototype infrared semiconductor with low toxicity and unique optical characteristics. Its quantum dots (QDs) accommodate ample intrinsic point defects which may actively participate in their rather complex photophysical processes. We synthesize CISe QDs with similar sizes but with distinct highly stoichiometry-deviating atomic ratios. The synthesis condition employing Se-rich precursors yields the Cu-deficient CISe QDs with special photophysical properties. The photoluminescence exhibits monotonic red shift from 680 to 775 nm when the ratio of Cu\'s proportion to In\'s decreases. The luminescence is found to stem from the copper vacancy and antisite defects. The CISe QDs exhibit Raman activity at 5.6, 6.9, and 8.7 THz that is separately assigned to Cu-Se and In-Se optical phonon modes and surface mode.

Nucleic acid detection plays a pivotal role in the accurate diagnosis of diseases. The CRISPR/Cas detection system, noted for its significant utility in a variety of applications, often necessitates enhanced sensitivity or specific signal amplification strategies, particularly for detecting low-abundance biomarkers. In this study, we present a quantum-dot-encoded beads (QDB)-energized CRISPR/Cas12-based lateral-flow assay (QDB-CRISPR-LFA). This method enables amplification-free, sensitive, and rapid detection (<40 min) of BRCA-1. We validated our method using contrived reference samples and nucleic acids extracted from tumor cells. The QDB-CRISPR-LFA provides a visual, more rapid alternative to the traditional BRCA-1 real-time RT-PCR assay. Significantly, through the integration of CRISPR\'s specificity and the high signal output of QDB, the detection threshold for BRCA-1 has been reduced to the femtomolar level, representing an enhancement of 2-4 orders of magnitude over existing CRISPR/Cas detection methods. This advancement underscores the potential of our approach in advancing nucleic acid detection techniques, which is crucial for the early and precise diagnosis of diseases.

Actin- and microtubule (MT)-based transport systems are essential for intracellular transport. During influenza A virus (IAV) infection, MTs provide long tracks for virus trafficking toward the nucleus. However, the role of the actin cytoskeleton in IAV entry and especially the transit process is still ambiguous. Here, by using quantum dot-based single-virus tracking, it was revealed that the actin cytoskeleton was crucial for the virus entry via clathrin-mediated endocytosis (CME). After entry via CME, the virus reached MTs through three different pathways: the virus (1) was driven by myosin VI to move along actin filaments to reach MTs (AF); (2) was propelled by actin tails assembled by an Arp2/3-dependent mechanism to reach MTs (AT); and (3) directly reached MTs without experiencing actin-related movement (NA). Therefore, the NA pathway was the main one and the fastest for the virus to reach MTs. The AT pathway was activated only when plenty of viruses entered the cell. The viruses transported by the AF and AT pathways shared similar moving velocities, durations, and displacements. This study comprehensively visualized the role of the actin cytoskeleton in IAV entry and transport, revealing different pathways for IAV to reach MTs after entry. The results are of great significance for globally understanding IAV infection and the cellular endocytic transport pathway.

In this study, the interaction of the human hemoglobin with cost effective and chemically fabricated CdS quantum dots (QDs) (average sizes ≈3nm) has been investigated. The semiconductor QDs showed maximum visible absorption at 445 nm with excitonic formation and band gap of ≈ 2.88 eV along with hexagonal crystalline phase. The binding of QDs-Hb occurs through corona formation to the ground sate complex formation. The life time of the heme pocket binding and reorganization were found to be t1 = 43 min and t2 = 642 min, respectively. The emission quenching of the Hb has been indicated large energy transfer between CdS QDs and Hb with tertiary deformation of Hb. The binding thermodynamics showed highly exothermic nature. The ultrafast decay during corona formation was studied from TCSPC. The results showed that the energy transfer efficiency increases with the increase of the QDs concentration and maximum ≈71.5 % energy transfer occurs and average ultrafast lifetime varies from 5.45 ns to1.51 ns. The deformation and unfolding of the secondary structure of Hb with changes of the α-helix (≈74 % to ≈51.07 %) and β-sheets (≈8.63 % to ≈10.25 %) have been observed from circular dichroism spectrum. The SAXS spectrum showed that the radius of gyration of CdS QDs-Hb bioconjugate increased (up to 23 ± 0.45 nm) with the increase of the concentration of QDs compare with pure Hb (11 ± 0.23 nm) and Hb becoming more unfolded.

Mercury (Hg), a notorious heavy metal with detrimental impacts on human health and the environment, necessitates the development of precise measurement methods. This study introduces an expeditious and straightforward photochemical approach to synthesize thioglycolic acid (TGA)-stabilized CdTe/CdS/ZnS core/multi-shell quantum dots (QDs). The synthesized CdTe/CdS/ZnS QDs were comprehensively characterized using fluorescence spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FESEM), and X-Ray diffraction (XRD). XRD and EDS results confirmed the successful formation of CdTe/CdS/ZnS structure. Also, FESEM and TEM results showed that CdTe/CdS/ZnS QDs were spherical. Results showed that synthesized Exhibiting vibrant green fluorescence and notable quenching in the presence of Hg2+ ions, these QDs emerge as promising candidates for fabricating a fluorescent sensor. The proposed sensor demonstrates notable sensitivity to Hg2+, featuring a detection limit of 16.32 nM and a linear range from 20 nM to 70 nM. The sensor\'s selectivity was confirmed by analyzing various anions and cations. Moreover, when tested with tap water, river water, and agricultural samples, the sensor exhibited reliable performance, validated by Inductively Coupled Plasma (ICP) analysis. Additionally, CdTe/CdS/ZnS QDs immobilized on micro pads proved effective for on-site water sample analysis, presenting a versatile solution for environmental monitoring.

CdS quantum dots (CdS QDs) are regarded as a promising photocatalyst due to their remarkable response to visible light and suitable placement of conduction bands and valence bands. However, the problem of photocorrosion severely restricts their application. Herein, the CdS QDs-Co9S8 hollow nanotube composite photocatalyst has been successfully prepared by loading Co9S8 nanotubes onto CdS QDs through an electrostatic self-assembly method. The experimental results show that the introduction of Co9S8 cocatalyst can form a stable structure with CdS QDs, and can effectively avoid the photocorrosion of CdS QDs. Compared with blank CdS QDs, the CdS QDs-Co9S8 composite exhibits obviously better photocatalytic hydrogen evolution performance. In particular, CdS QDs loaded with 30% Co9S8 (CdS QDs-30%Co9S8) demonstrate the best photocatalytic performance, and the H2 production rate reaches 9642.7 μmol·g-1·h-1, which is 60.3 times that of the blank CdS QDs. A series of characterizations confirm that the growth of CdS QDs on Co9S8 nanotubes effectively facilitates the separation and migration of photogenerated carriers, thereby improving the photocatalytic hydrogen production properties of the composite. We expect that this work will facilitate the rational design of CdS-based photocatalysts, thereby enabling the development of more low-cost, high-efficiency and high-stability composites for photocatalysis.

The self-assembly of nanocrystals (NCs) into close-packed, ordered superlattices (SLs) is of broad, engineering interest. The coherent orientation of polyhedral nanocrystals within NC SLs enhances electronic, magnetic, and vibrational coupling, leading to a variety of emergent phenomena. Here, we show that coherent orientation of polyhedral NCs in many SLs can be understood simply by considering its effect on the conformational entropy of surface ligands. We report the predicted nanocrystal orientations and entropic driving force to orient for a broad range of nanocrystal shapes and superlattice unit cells, and we show that ligand entropy is sufficient to reproduce a host of reported experimental and computational observations. We additionally use this framework to predict the expected distribution of interstitial species such as solvent or unbound ligands in an oriented NC SL. This work offers intuition for understanding the orientation of NCs in superlattices and a future framework for analyzing multinary structures.

Short-wave infrared (SWIR) light-emitting diodes (LEDs) have emerged as promising technologies for diverse applications such as optical communication, biomedical imaging, surveillance, and machine vision. Colloidal quantum dots (QDs) are particularly attractive for SWIR LEDs due to their solution processability, compatibility with flexible substrates, and tunable absorption and luminescence. However, the presence of toxic elements or precious metals in most SWIR-emitting QDs poses health, environmental, and cost challenges. In this context, CuInS2 (CIS) QDs are known for low toxicity, cost-effective fabrication, and SWIR-light emitting capability. However, CIS QDs have not yet been directly utilized to fabricate SWIR LEDs to date, which is due to low particle stability, inefficient charge carrier recombination, and significantly blue-shifted luminescence after integrating into LED devices. To address challenges, we propose a dual-passivation strategy using ZnI2 as a chemical additive to enhance both the optical property of plain CIS QDs and charge carrier recombination upon LED device implementation. The resulting CIS-QD-based LEDs exhibit a stable SWIR electroluminescence (EL) peak (over 1000 nm) with a high EL radiance and a record external quantum efficiency in the SWIR region. Our study represents a significant step forward in SWIR-QLED technology, offering a pathway for the development of high-performance, low-cost, and nontoxic SWIR light sources.

We study the electron tunneling (ET) and local Andreev reflection (AR) processes in a quantum dot (QD) coupled to the left and right ferromagnetic leads with noncollinear ferromagnetisms. In particular, we consider that the QD is also side-coupled to a nanowire hosting Majorana bound states (MBSs) at its ends. Our results show that when one mode of the MBSs is coupled simultaneously to both spin-up and spin-down electrons on the QD, the height of the central peak is different from that if the MBS is coupled to only one spin component electrons. The ET and AR conductances, which are mediated by the dot-MBS hybridization, strongly depend on the angle between the left and right magnetic moments in the leads. Interaction between the QD and the MBSs will result in sign change of the angle-dependent tunnel magnetoresistance. This is very different from the case when the QD is coupled to regular fermonic mode, and can be used for detecting the existence of MBSs, a current challenge in condensed matter physics under extensive investigations.