Article
Chemistry, Analytical
Luping Tang, Yangyang Zhang, Chen Liao, Yingqing Guo, Yingtao Lu, Yixuan Xia, Yiwei Liu
Summary: In this study, the temperature-dependent photoluminescence (PL) properties of CdS/ZnS core/shell quantum dots (QDs) were investigated. The results showed that the band-edge emission (BEE) intensity decreased with increasing temperature, while the surface-state emission (SSE) intensity first increased and then decreased. The PL spectra exhibited a redshift in peak energies and an increase in full width at half-maximum (FWHM) as the temperature increased. Furthermore, the CIE chromaticity coordinates showed a dramatic change with temperature. These findings suggest that CdS/ZnS core/shell QDs have potential applications as temperature sensors.
Article
Chemistry, Physical
Byeong Guk Jeong, Jun Hyuk Chang, Donghyo Hahm, Seunghyun Rhee, Myeongjin Park, Sooho Lee, Youngdu Kim, Doyoon Shin, Jeong Woo Park, Changhee Lee, Doh C. Lee, Kyoungwon Park, Euyheon Hwang, Wan Ki Bae
Summary: This study presents an approach to control the potential profile of III-V-II-VI h-NCs by steering dipole densities at the interface, allowing for control of the optical and electrical characteristics of these heterostructured nanocrystals. The synthesis of h-NCs with atomic precision enables correlation of interfacial dipole moments with the crystals' photochemical stability and optoelectronic performance. Controlled synthesis of heterostructured III-V-II-VI nanocrystals demonstrates that dipole moments formed at the core-shell interface can tune the optoelectronic properties of these nanomaterials and their performance in light-emitting devices.
Article
Chemistry, Physical
Vineet Sharma, Mohan Singh Mehata
Summary: Water dispersible 3-mercaptoproponic acid protected Mn@ZnSe QDs were used for sensing mercury and lead ions. The system showed strong interaction and response to the metal ions, providing a new possibility for dual response ion detection in real samples.
CHEMICAL PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Rui Cheng, Zhi-Bin Liang, Haixia Shen, Jiazhuang Guo, Cai-Feng Wang, Su Chen
Summary: In this work, color-tunable fluorescent formamidinium lead halogen (FAPbX3, X = Cl, Br, I) PQDs/polymer core-shell nanofiber films were fabricated using a microfluidic electrospinning method. The high stability and PL quantum yield make these films highly promising for optoelectronic applications.
CHINESE CHEMICAL LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Xue Bai, Finn Purcell-Milton, Yurii K. Gun'ko
Summary: Cu-Based quantum dots are being explored as a potential replacement for toxic Cd- or Pb-based QDs, with studies focusing on the impact of different reaction conditions on the resulting morphologies and optical properties. By carefully controlling the ZnS shell deposition, researchers have optimized the synthesis of CIZS/ZnS/ZnS QDs and produced highly fluorescent core/shell/shell heterostructured QDs with high PLQYs. Additionally, the successful creation of giant ZnS shell QDs opens up possibilities for further development in this area.
Article
Optics
Yanqing Zhu, Cong Shen, Xueqing Xu, Jianhua Zou, Lei Wang, Xudong Cheng, Jingqiu Liang, Xiudi Xiao, Gang Xu
Summary: This study investigates the effect of halogen acid treatment on the luminescence properties of InP/GaP/ZnS quantum dots (QDs). It is found that hydrofluoric acid (HF) and hydrochloric acid (HCl) can improve the optical properties of QDs, while hydrobromic acid (HBr) and hydroiodic acid (HI) are not conductive to enhance the photoluminescence quantum yield (PL QY) of QDs. HF and HCl can effectively etch the oxidative layer and passivate the surface indium dangling bonds in the form of atomic ligands. The proposed charge carrier recombination model suggests that the significantly improved PL QY after acid treatment is attributed to the recombination of electron-hole pairs mainly from the conduction band and valence band. InP QDs treated with HF exhibit the best luminescence properties, with a high PL QY of 96%, offering great potential for advanced optoelectronic devices.
JOURNAL OF LUMINESCENCE
(2023)
Article
Materials Science, Multidisciplinary
Faiza Mustafa, Samia Aslam, Asim Arshad, Ashfaq Ahmad, Sadia Sagar, Sining Yun
Summary: This research presents the successful formation of ZnSe/amino functionalized graphene quantum dots (af-GQDs) with type-II core-shell structures. The structures show potential as a single emissive layer and exhibit tunable photoluminescence emission in the visible region. The introduction of functional groups on af-GQDs enhances their properties and reduces Auger recombination. The study also investigates the emission properties of ZnSe/af-GQDs through steady state and temperature dependent photoluminescence spectroscopy, as well as characterizes the structure using X-ray photon spectroscopy measurements. The findings suggest that ZnSe/af-GQDs have great potential for LEDs and display devices.
APPLIED MATERIALS TODAY
(2022)
Article
Chemistry, Physical
Dipika Das, Raj Kumar Dutta
Summary: In this study, a methodology using photoluminescence lifetime of glutathione capped CdTe/CdS core-shell quantum dots probe was demonstrated to detect nickel ions in aqueous medium. The ratio of (tau avg)probe/(tau avg)probe+Ni2+ was developed as an analytical signal with sensitivity of 0.61 L/mg and detection limit of 23 μg/L. The method was not applicable for detecting Cu2+, but the results suggest promising potential for detecting metal ions, particularly those exhibiting dynamic photoluminescence quenching.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
(2021)
Article
Biochemical Research Methods
Olga A. Goryacheva, K. David Wegner, Aleksandr M. Sobolev, Ines Haeusler, Nikolai Gaponik, Irina Y. Goryacheva, Ute Resch-Genger
Summary: Light-emitting nanoparticles, known as quantum dots (QDs), have great potential for biosensing and bioimaging applications. However, their use in biological systems requires them to be water-dispersible without affecting their optical properties. In this study, researchers developed a new surface silanization method to preserve the optical properties of QDs and successfully prepared water-dispersible QDs.
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
(2022)
Article
Nanoscience & Nanotechnology
Hongyue Wang, Jialiang Gao, Miao Zhang, Peng Liu, Yangyang Guo, Huixin Li, Guanguan Zhao, Siliang Hu, Zeyi Cheng, Jianyang Zang, Ruijuan Wen, Taihong Liu, Yu Tong, Zhenhua Sun, Hongqiang Wang
Summary: This work systematically investigates the spectroscopic properties of Mn2+-doped ZnSe/ZnS core-shell quantum dots (QDs). It is found that increasing the doping concentration can enhance the photoluminescence quantum yield (PL QY) of the Mn2+ dopant, but excessive doping leads to the magnetic coupling of Mn2+ ions, resulting in abnormal variations in the photoluminescence intensity and linewidth with temperature.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Muhammad Haroon Rashid, Ants Koel, Toomas Rang, Nadeem Nasir, Nadeem Sabir, Faheem Ameen, Abher Rasheed
Summary: Quantum-dot-based core/shell structures have gained significance recently due to their optical, optoelectronic, and magnetic attributes. This study developed novel Cu-doped CdS/ZnS shell structures to enhance photoluminescence properties. Experimental results showed that Cu-doped ZnS shells adopted the crystal structure of CdS, minimizing lattice mismatch and offering better passivation, resulting in increased photoluminescence.
Article
Chemistry, Physical
Ho-Kyung Lee, Ye-Jun Ban, Hyun-Jong Lee, Ji-Hyeon Kim, Sang-Joon Park
Summary: In this paper, a new blue-emitting material called CuCrS2/ZnS QDs (CCS QDs) was introduced. The CCS QDs were prepared in a core/shell structure through a one-pot synthesis using 1-dodecanethiol as a sulfur source and co-ligand. The CCS QDs exhibited a semi-spherical colloidal nanocrystalline shape with an average diameter of 9.0 nm and ZnS shell thickness of 1.6 nm. The PL max was observed at 465 nm with an excitation wavelength of 400 nm and PLQY was 5% at an initial [Cr3+]/[Cu+] molar ratio of one in the core synthesis. With an increase in the initial molar ratio, the CCS QDs showed slightly blue-shifted PL emission spectra and increased PLQY, reaching a maximum of 10% at a molar ratio of 2.0 (462 nm PL max). However, when the initial molar ratio exceeded two, non-emissive Cr2S3 nanoflakes formed, resulting in a lower photoluminescence quantum yield of 4.5% with a PL max of 461 nm at a molar ratio of four.
Article
Optics
E. Irani, E. Yazdani, A. Bayat
Summary: The structural and optical properties of high luminescent CdTe/CdS core/shell quantum dots in a stable, aqueous medium have been investigated, revealing wavelength tunability by adjusting the shell thickness. A 10 nm shell thickness for CdS showed higher photoluminescence quantum yield and improved optical nonlinearities compared to CdTe quantum dots and CdTe/CdS core/shell quantum dots with 16 nm thickness.
Article
Optics
Xia Ran, Congcong Chen, Zhongran Wei, Zhen Chi, Yatao Pan, Yanmin Kuang, Xiaojuan Wang, Lijun Guo
Summary: This study investigates the shell-dependent blinking behavior and carrier dynamics in CdxZn1-xSeyS1-y@ZnS core/shell quantum dots. The results show that the on-time fraction of blinking emission can be effectively increased by capping the ZnS shell, and the carrier dynamics exhibit dependence on the shell thickness. These findings demonstrate the importance of shell encapsulation in regulating the optical properties of quantum dots.
JOURNAL OF LUMINESCENCE
(2022)
Article
Nanoscience & Nanotechnology
Swati Mukherjee, Joicy Selvaraj, Thangadurai Paramasivam
Summary: The study presents a synthesis method for non-toxic Ag:ZIS/ZS core/shell QDs, showing that the shell thickness has a significant impact on the photophysics of the QDs.
ACS APPLIED NANO MATERIALS
(2021)
Article
Chemistry, Physical
Vineet Sharma, Mohan Singh Mehata
Summary: Water dispersible 3-mercaptoproponic acid protected Mn@ZnSe QDs were used for sensing mercury and lead ions. The system showed strong interaction and response to the metal ions, providing a new possibility for dual response ion detection in real samples.
CHEMICAL PHYSICS LETTERS
(2022)
Article
Chemistry, Analytical
Nupur Pandey, Sanjay Pant, Mohan Singh Mehata
Summary: This study explored the fluorescence quenching of 3-aminoquinoline by halide ions in an aqueous acidic medium, and found that I- ions showed the strongest quenching effect on the fluorescence intensity.
Article
Materials Science, Multidisciplinary
Preeti Bhatt, Chandra Kala Pant, Pramod Pandey, Yogesh Pandey, Satish Chandra Sati, Mohan Singh Mehata
Summary: This study systematically investigated the adsorption behavior of the nucleic acid base Cytosine (CYN) on the surface of Montmorillonite (MMT). It was found that metal ions have a significant impact on the quantity of CYN adsorbed on different solid surfaces. Langmuir isotherm model showed that the adsorption behavior is a monolayer formation on MMT and MMT-M2+ surfaces. SEM, XRD, and FTIR confirmed the results. This research sheds light on the interaction between MMT clay and biogenic metal ions, providing insights into the protection and stabilization of biomonomers during chemical evolution.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Chemistry, Analytical
Babita Bisht, Pinki Dey, Avinash Kumar Singh, Sanjay Pant, Mohan Singh Mehata
Summary: This study investigated the interaction between DY-27 and BSA using multi-spectroscopic techniques. The results showed the formation of a stable complex between DY-27 and BSA, leading to fluorescence quenching and conformational changes in the secondary structure of BSA. The calculated parameters supported the proposed quenching mechanism and confirmed the spontaneity of the binding process. Docking studies provided further insights into the interactions between DY-27 and serum albumin.
METHODS AND APPLICATIONS IN FLUORESCENCE
(2022)
Article
Chemistry, Physical
Shahid Husain, Nupur Pandey, Nisha Fatma, Sanjay Pant, Mohan Singh Mehata
Summary: The effect of solvents on the absorption and fluorescence spectra of 3,5-diaminobenzoic acid was investigated. It was found that the polarity and hydrogen bonding ability of solvents can modify its spectral characteristics. The solvent acidity and dipolarity were shown to influence the absorption and fluorescence spectra. The preferential solvation concept was used to explain the spectral variations in different solvents.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Physical
Neha Bhatt, Mohan Singh Mehata
Summary: Highly stable gold nanoparticles (AuNPs) of different sizes were successfully synthesized using a specific plant, Kalanchoe fedtschenkoi, through an eco-friendly and cost-efficient method. The AuNPs showed strong surface plasmon resonance (SPR) at around 525 nm. The physiochemical environments, pH, and temperature were investigated, and the crystal structure, stability, morphology, structure, and bonds of the AuNPs were analyzed. Additionally, the interaction of AuNPs with plasma protein and their catalytic activity in the degradation of methylene blue (MB) dye were studied.
Article
Chemistry, Analytical
Nisha Fatma, Sanjay Pant, Nupur Pandey, Mohan Singh Mehata
Summary: This study investigated the influence of different halides on the excited state dynamics of 6-methoxyflavone (6MF) in an aqueous solution. The fluorescence of 6MF quenched significantly upon addition of I- and Br- ions. The quenching process was categorized by Stern-Volmer and Lehrer equations, and parameters such as K-SV, KSV-L, and k(q) were higher for I- ions than Br- ions. The study reveals the importance of 6MF for sensing/detection applications, particularly in a pure aqueous environment (pH > 7).
METHODS AND APPLICATIONS IN FLUORESCENCE
(2023)
Article
Materials Science, Multidisciplinary
Aneesha, Nobuhiro Ohta, Mohan Singh Mehata
Summary: Stable blue fluorescent WS2 quantum dots were successfully synthesized via a single-step hydrothermal method at pH 11. The WS2 QDs exhibited excellent stability, water dispersibility, and significant photoluminescence properties. The absorption and photoluminescence of the WS2 QDs were highly sensitive to hydrogen peroxide, allowing for quenching and recovery through oxidation-reduction reactions. This study demonstrates the potential of WS2 QDs as a sensitive and stable fluorescent probe for biological applications.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Electrochemistry
R. Kumar, R. K. Ratnesh, Jay Singh, R. Chandra, G. Singh, V. Vishnoi
Summary: This paper presents a cost-effective data acquisition and medical imaging system using electrical impedance tomography (EIT). The system utilizes a modified imaging algorithm to reconstruct images from the electrical conductivity distribution of a test object or phantom. The experimental setup includes convertible electrodes and a static current source, while the data acquisition procedure utilizes a GUI to provide a user-friendly interface. Performance testing with various phantom models demonstrates the innovative and enhanced functionality of the proposed system in the engineering society.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2023)
Article
Engineering, Electrical & Electronic
Vijay Singh Meena, Ajay Kumar Saini, Anand Singh, Sumit Jain, Devendra Kumar Rana, Mohan Singh Mehata
Summary: Four-layer anti-reflection coating film stacks were grown on the backside of the HgCdTe-CdZnTe assembly using the thermal-evaporation deposition technique. The ARC film stacks exhibited desired surface morphology, elemental composition, and micro-structural features. The reflectance of HgCdTe-CdZnTe assembly was reduced to less than 1.0% within the mid-wave infrared spectral region, proving the effectiveness of the four-layer ARC film stacks.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Vijay Singh Meena, Ajay Kumar Saini, Anand Singh, Sumit Jain, Ranveer Singh, Mohan Singh Mehata
Summary: Gold (Au) thin films were deposited on the HgCdTe surface using thermal evaporation deposition. The thermally grown Au films had desired structure, elemental compositions, and purity. The films exhibited low roughness and ideal grain size. The optimized Au films were used to fabricate Ohmic contacts for HgCdTe infrared detectors, exhibiting low specific contact resistance.
Article
Biochemistry & Molecular Biology
Mohan Singh Mehata, Aneesha
Summary: 7-azaindole (7AI) dimer is a model molecule that helps with understanding mutagenic behavior in DNA through a proton transfer process. The fluorescence intensity of both neutral and protonated forms of 7AI can be used to create a fluorescent sensor for selective metal ion recognition. Among various metal ions, the absorption, fluorescence, and fluorescence lifetime of 7AI in water are specifically sensitive to ferric (Fe3+) ions. The detection limit (LoD) for Fe3+ ions using fluorescence spectra is around 0.46 +/- 0.02 μM for the neutral form and 0.49 +/- 0.02 μM for the protonated form of 7AI.
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
(2023)
Proceedings Paper
Materials Science, Multidisciplinary
Vijay Singh Meena, Ajay Kumar Saini, Devendra Kumar Rana, Mohan Singh Mehata
Summary: Polycrystalline CdS thin films with a hexagonal crystal structure were grown on a silicon substrate using thermal evaporation deposition method. The films exhibited pure and stoichiometric composition, uniform and smooth surface, and good adhesion. The CdS films have potential applications in solar cell and infrared detector fabrication due to their stability, wide bandgap, high transmission, environmental tolerance, and mechanical strength.
MATERIALS TODAY-PROCEEDINGS
(2022)
Article
Engineering, Multidisciplinary
Deepak Kumar, Mohan Singh Mehata
Summary: Diamagnetic zinc oxide nanoparticles with a wurtzite structure were synthesized. The nanoparticles exhibited dual photoluminescence peaks and showed high efficiency in the photocatalytic degradation of congo red dye under UV irradiation.
INDIAN JOURNAL OF ENGINEERING AND MATERIALS SCIENCES
(2022)
Proceedings Paper
Materials Science, Multidisciplinary
Samiksha Shukla, Anne Masih, Aryan, Mohan Singh Mehata
Summary: This study presents a green route to synthesize silver nanoparticles (Ag-NPs) using green leaves of Crinum asiaticum and investigates how biomolecules in Crinum asiaticum lead to the formation of Ag-NPs. The size, morphology, crystalline structure, and stability of Ag-NPs were examined using various techniques, and the results show that Ag-NPs exhibit appreciable catalytic properties.
MATERIALS TODAY-PROCEEDINGS
(2022)
