Article
Chemistry, Multidisciplinary
Kazuhiro Nemoto, Junpei Watanabe, Hong-Tao Sun, Naoto Shirahata
Summary: This study reports the coherent growth of zinc sulfide on a colloidal indium phosphide quantum dot, resulting in an InP/ZnS core/shell structure with a single lattice constant. The bandgap of the core quantum dot increases under certain conditions, leading to a blueshift in absorption and photoluminescence spectra. The quantum yield and bandwidth of photoluminescence are enhanced based on the strengthened quantum confinement effect.
Article
Chemistry, Physical
Paul Cavanaugh, Ilan Jen-La Plante, Christian Ippen, Ruiqing Ma, David F. Kelley, Anne Myers Kelley
Summary: Resonance Raman spectra and absolute cross sections of InP/ZnSe/ZnS core/shell/shell nanocrystals were obtained at different excitation wavelengths, revealing differences in phonon features attributed to various stoichiometries of the structures. The presence of excess indium in the ZnSe shell was found to influence the Raman intensities and frequency distributions, supporting previous assignments of hole trapping at indium defects in the shell.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Zhiwei Long, Gaoling Yang, Ruiwen Shao, Zhuo Chen, Yang Liu, Ronghui Liu, Haizheng Zhong
Summary: The growth of ZnS shell on ZnSe cores of different sizes is investigated. By controlling the reactivity of Zn and S precursors, the ZnS shell growth can be tuned to defect-related strain-released or defect-free strained mode, resulting in blue and red-shifts of the nanocrystals. The shape of the nanocrystals evolves differently depending on the growth mode, and the strain between the core and shell affects the band alignment and quantum yield.
Article
Chemistry, Physical
Haochen Sun, Paul Cavanaugh, Ilan Jen-La Plante, Christian Ippen, Maria Bautista, Ruiqing Ma, David F. Kelley
Summary: Transient absorption and time-resolved photoluminescence spectroscopies were used to study the hole tunneling and Auger dynamics in high-quality InP/ZnSe/ZnS quantum dots. The study revealed that trapped holes can tunnel into the valence band, converting one type of biexciton to another type.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Wandi Chen, Wenwen Wang, Lei Sun, Shiyao Chen, Qun Yan, Tailiang Guo, Xiongtu Zhou, Chaoxing Wu, Yongai Zhang
Summary: A study on InP/ZnSe/ZnS quantum dot photoresist film was conducted, investigating the influence of film thickness and the mass ratio of quantum dots to photoresist on the photoluminescence quantum yield. The results showed that patterned quantum dot layers exhibited higher photoluminescence quantum yield and color coordinates under certain conditions.
OPTICAL MATERIALS EXPRESS
(2022)
Article
Chemistry, Multidisciplinary
Taehee Kim, Yu-Ho Won, Eunjoo Jang, Dongho Kim
Summary: The study reveals that the Auger recombination processes of InP/ZnSe/ZnS quantum dots are influenced by the midshell structures, ultimately affecting the performance of QD-LEDs. The midshell thickness impacts the exciton-exciton binding energy and the negative trion Auger recombination behavior.
Article
Chemistry, Physical
Jiakuan Zhang, Chuyue Li, Jiongzhao Li, Xiaogang Peng
Summary: Size- and shape-controlled CdSe/ZnSe core/shell and CdSe/ZnSe/ZnS core/shell/shell nanocrystals with zinc-blende structure are synthesized. The ligand strain between the inorganic crystal surface and organic ligands plays a key role in ZnSe epitaxy. The lattice strain between the CdSe and ZnSe affects the photoluminescence of CdSe/ZnSe/ZnS core/shell/shell QDs.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Physical
Paulina Jaimes, Tsumugi Miyashita, Tian Qiao, Kefu Wang, Ming Lee Tang
Summary: In this study, an inverse Type-I heterostructure with an inner InP shell was used for triplet-triplet annihilation-based photon upconversion. The addition of a ZnS shell on ZnSe/InP core/shell particles increased the photoluminescence quantum yield and transmitter triplet lifetime, while decreasing the rate of triplet energy transfer. The photon upconversion quantum yield of the ZnSe/InP/ZnS nanocrystals was found to be around 4.0%, suggesting their potential for converting near-infrared photons to visible light.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Paulina Jaimes, Tsumugi Miyashita, Tian Qiao, Kefu Wang, Ming Lee Tang
Summary: In this work, nanocrystals with an inner InP shell were used for triplet-triplet annihilation-based photon upconversion. The InP-based nanocrystals are earth-abundant and can be synthetically tuned to absorb in the NIR window. A two monolayer ZnS shell was used to passivate surface defects and improve the photoluminescence quantum yield of the InP nanocrystals. The ZnSe/InP/ZnS nanocrystals showed promising results in photon upconversion and can potentially convert NIR photons to visible light.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Physics, Applied
Takafumi Moriyama, Akihito Kumamoto, Makoto Kido, Hirokazu Sasaki, Thomas Novet, Naoya Shibata, Yuichi Ikuhara
Summary: Indium phosphide (InP) quantum dots (QDs) are attractive alternatives to cadmium- and lead-based emitters for wide-color gamut displays. However, the wider emission full-width at half-maximum (FWHM) of InP-QDs has hindered their application. This study demonstrates that the presence of ZnCl2 during shell formation significantly improves the emission properties of InP-QDs. The addition of ZnCl2 results in the formation of uniform and spherical particles, enabling kilogram-scale synthesis while maintaining excellent emission properties.
APPLIED PHYSICS EXPRESS
(2023)
Article
Chemistry, Physical
Shijia Zeng, Wenjiang Tan, Jinhai Si, Liuhao Mao, Jinwen Shi, Yuren Li, Xun Hou
Summary: Through ultrafast spectroscopy, it was found that InP/ZnSe/ZnS core/shell/shell quantum dots exhibit better electron transfer capability compared to InP/ZnS quantum dots, as the introduction of ZnSe midshell improves passivation and enhances exciton delocalization. Temperature-dependent PL spectra indicate that the exciton-phonon coupling strength and exciton binding energy of InP/ZnSe/ZnS quantum dots are smaller. Further photocatalytic hydrogen evolution testing shows that InP/ZnSe/ZnS quantum dots have significantly higher photocatalytic activity and improved stability.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Paul Cavanaugh, Haochen Sun, Ilan Jen-La Plante, Maria J. Bautista, Christian Ippen, Ruiqing Ma, Anne Myers Kelley, David F. Kelley
Summary: In this study, time-correlated single photon counting was used to investigate the radiative dynamics of InP/ZnSe/ZnS core/shell/shell quantum dots with varying amounts of excess indium. The results show that QDs with excess indium exhibit different luminescence kinetics, attributed to the transient population of indium-based hole traps in the ZnSe shell. This indicates a complex interplay between shell thickness, core/shell interfaces, and the distribution of indium-based hole traps within the QDs.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Jingwen Feng, Maocheng Jiang, Dong Li, Yuanming Zhang, Chen Pei, Li Zhou, Zhuo Chen, Yanzhao Li, Xinguo Li, Xiaoguang Xu
Summary: Researchers have successfully developed a high-performance, heavy metal-free quantum dot light-emitting diode for eco-friendly displays. By adjusting the ratio of Te/Se in the core, they were able to create blue quantum dots with adjustable energy levels and emission peaks. By optimizing the microcavity structure and electrical properties, they achieved a chroma efficiency of 72 for the blue devices, which is 2.2 times higher than the control device.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Nayon Park, Forrest W. Eagle, Asher J. DeLarme, Madison Monahan, Talia LoCurto, Ryan Beck, Xiaosong Li, Brandi M. Cossairt
Summary: This study demonstrates fine-tuning of the atomic composition of InP/ZnSe quantum dots at the core/shell interface, affecting their optical properties. Reactive trimethylsilyl reagents were used to shift the nanocrystal stoichiometry, resulting in changes in absorption, excitonic photoluminescence, and trap-based photoluminescence. Time-resolved photoluminescence data suggest that the low photoluminescence quantum yields may be attributed to the creation of new charge trap states and a dark population within the QDs.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Anh T. Nguyen, Paul Cavanaugh, Ilan Jen-La Plante, Christian Ippen, Ruiqing Ma, David F. Kelley
Summary: This study investigates the negative trion and biexciton Auger dynamics in high-quality InP/ZnSe/ZnS quantum dots with varying amounts of indium-based traps in the ZnSe shell. The Auger times are found to vary and scale linearly with particle volume, with excess indium leading to the transient population of hole traps. Biexciton dynamics, including XX and XT states, are determined through transient absorption measurements, revealing differences in Auger recombination between stoichiometric and nonstoichiometric particles. Additionally, the study shows a correlation between the fraction of XT state formation and the product of slow photoluminescence rise and rise time constant following one-photon excitation.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Marina Rodio, Matthias Graf, Florian Schulz, Niclas S. Mueller, Manfred Eich, Holger Lange
Article
Multidisciplinary Sciences
Niclas S. Mueller, Yu Okamura, Bruno G. M. Vieira, Sabrina Juergensen, Holger Lange, Eduardo B. Barros, Florian Schulz, Stephanie Reich
Article
Multidisciplinary Sciences
Florian Schulz, Ondrej Pavelka, Felix Lehmkuehler, Fabian Westermeier, Yu Okamura, Niclas S. Mueller, Stephanie Reich, Holger Lange
NATURE COMMUNICATIONS
(2020)
Article
Optics
Kartik Ayyer, P. Lourdu Xavier, Johan Bielecki, Zhou Shen, Benedikt J. Daurer, Amit K. Samanta, Salah Awel, Richard Bean, Anton Barty, Martin Bergemann, Tomas Ekeberg, Armando D. Estillore, Hans Fangohr, Klaus Giewekemeyer, Mark S. Hunter, Mikhail Karnevskiy, Richard A. Kirian, Henry Kirkwood, Yoonhee Kim, Jayanath Koliyadu, Holger Lange, Romain Letrun, Jannik Lubke, Thomas Michelat, Andrew J. Morgan, Nils Roth, Tokushi Sato, Margin Sikorski, Florian Schulz, John C. H. Spence, Patrik Vagovic, Tamme Wollweber, Lena Worbs, Oleksandr Yefanov, Yulong Zhuang, Filipe R. N. C. Maia, Daniel A. Horke, Jochen Kuepper, N. Duane Loh, Adrian P. Mancuso, Henry N. Chapman
Summary: Single particle imaging at XFELs has the potential to determine the structure and dynamics of single biomolecules at room temperature. By overcoming hurdles in collecting high-quality diffraction patterns and computational purification, researchers have successfully obtained sub-nano meter resolution 3D reconstructions for biomolecular imaging. These advancements in X-ray sources, detectors, sample delivery, and data analysis algorithms illuminate new possibilities for characterizing diverse ensembles at the structural level.
Article
Chemistry, Multidisciplinary
Niclas S. Mueller, Emanuel Pfitzner, Yu Okamura, Georgy Gordeev, Patryk Kusch, Holger Lange, Joachim Heberle, Florian Schulz, Stephanie Reich
Summary: Research shows that plasmonic supercrystals, with a high density of hotspots, are an excellent platform for enhancing vibrational spectra by increasing the cross section of Raman scattering and infrared absorption. The study demonstrates that the intensity of surface-enhanced Raman scattering inside the crystal is uniform and predictable, with supercrystal polaritons inducing resonances in the enhanced cross section for both Raman scattering and infrared absorption. The enhancement of infrared absorption within supercrystals is attributed to the combined effects of hotspot formation and the excitation of standing polariton waves.
Article
Nanoscience & Nanotechnology
Yannic U. Staechelin, Dominik Hoeing, Florian Schulz, Holger Lange
Summary: Hot electrons in metal nanoparticles thermalize with the lattice via electron-phonon coupling, and this process is influenced by the particle's crystalline structure and size. Size dependency is not observed in polycrystalline particles, while monocrystalline particles exhibit a size-dependent electron-phonon coupling, with larger particles showing slower coupling due to decreased electron-surface scattering effects.
Article
Chemistry, Physical
Yannic U. Staechelin, Michael Deffner, Sonja Krohn, Christian Castillo Delgadillo, Jan Steffen Niehaus, Holger Lange
Summary: By optical and THz pump-probe spectroscopy, we find that only shell-located electrons in quantum rods contribute to photoconductivity, while core-located carriers form immobile excitons that respond to external electrical fields.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Yulong Zhuang, Salah Awel, Anton Barty, Richard Bean, Johan Bielecki, Martin Bergemann, Benedikt J. Daurer, Tomas Ekeberg, Armando D. Estillore, Hans Fangohr, Klaus Giewekemeyer, Mark S. Hunter, Mikhail Karnevskiy, Richard A. Kirian, Henry Kirkwood, Yoonhee Kim, Jayanath Koliyadu, Holger Lange, Romain Letrun, Jannik Luebke, Abhishek Mall, Thomas Michelat, Andrew J. Morgan, Nils Roth, Amit K. Samanta, Tokushi Sato, Zhou Shen, Marcin Sikorski, Florian Schulz, John C. H. Spence, Patrik Vagovic, Tamme Wollweber, Lena Worbs, P. Lourdu Xavier, Oleksandr Yefanov, Filipe R. N. C. Maia, Daniel A. Horke, Jochen Kuepper, N. Duane Loh, Adrian P. Mancuso, Henry N. Chapman, Kartik Ayyer
Summary: One of the outstanding problems in X-ray single-particle imaging is the classification of structural heterogeneity. This paper proposes two methods that can account for orientation-induced variation and determine the structural landscape of a sample ensemble. The methods are validated using experimental data and can recover discrete structural classes and continuous deformations.
Article
Chemistry, Multidisciplinary
Hannes Van Avermaet, Pieter Schiettecatte, Sandra Hinz, Luca Giordano, Fabio Ferrari, Celine Nayral, Fabien Delpech, Janina Maultzsch, Holger Lange, Zeger Hens
Summary: This study presents a synthesis protocol for forming InP-based quantum dots with high quantum efficiency across the full visible spectrum. By introducing specific interfacial treatments and a core/shell/shell structure, the researchers achieved the intended emission color while minimizing line broadening caused by lattice mismatch. The realization of this high quantum efficiency in full-spectrum color conversion will greatly facilitate research into light-matter interaction.
Article
Materials Science, Multidisciplinary
Florian Schulz, Holger Lange
Summary: Periodic arrangements of plasmonic nanoparticles in supercrystals exhibit strong light-matter interaction. This study analyzes experimental data to investigate the reproducibility and tunability of gap sizes in relation to the particle diameter and molecular weight of stabilizing ligands. Different behaviors of polystyrene-based ligands are observed depending on their molecular weight, leading to important consequences for the correlation between nanoparticle diameter and resulting gaps in supercrystals. An alternative volume-based approach is proposed for predicting gap sizes in larger nanoparticles, which provides robust guidelines for achieving gaps below 5 nm for enhanced light-matter coupling.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Chemistry, Physical
Robert Salzwedel, Andreas Knorr, Dominik Hoeing, Holger Lange, Malte Selig
Summary: We present a microscopic approach to understand the beginning of radial oscillation in silver nanoparticles. Using the Heisenberg equation of motion framework, we demonstrate that the coupled dynamics of coherent electron occupation and coherent phonon amplitude induce periodic size oscillations in the nanoparticle. Our results suggest a more direct coupling mechanism between field intensity and coherent phonons, which triggers size oscillations via optically induced electron density gradient. This mechanism is more efficient than the incoherent heating process commonly discussed in literature and provides a better explanation for the early onset of oscillations observed in recent experiments.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Dominik Hoeing, Robert Salzwedel, Lena Worbs, Yulong Zhuang, Amit K. K. Samanta, Jannik Lubke, Armando D. D. Estillore, Karol Dlugolecki, Christopher Passow, Benjamin Erk, Nagitha Ekanayake, Daniel Ramm, Jonathan Correa, Christina C. Papadopoulou, Atia Tul Noor, Florian Schulz, Malte Selig, Andreas Knorr, Kartik Ayyer, Jochen Kupper, Holger Lange
Summary: Currently, the dynamics of optically excited plasmonic nanoparticles are explained as a series of scattering events caused by nanoparticle breathing oscillations initiated by statistical heat transfer from thermalized electrons to the lattice. However, a phase mismatch between theory and experiments suggests an additional excitation mechanism. Through optical transient absorption spectroscopy and time-resolved single-particle X-ray diffractive imaging, we found that optically induced electron density gradients are the initial driving source for breathing oscillation and confirmed the need for an additional excitation mechanism for thermal expansion. Our new model reproduces all experimental observations.
Article
Optics
Yannic U. Staechelin, Tobias Kroh, Franz X. Kaertner, Holger Lange
Summary: Optical-pump-terahertz-probe (OPTP) experiments are commonly used to study the behaviors of excited carriers in semiconductors. However, the size difference between the probe beam and the pump beam can cause distortions in the sample response and uncertainties in calculated conductivities and models. By investigating the influence of pump beam spot size and evaluating model calculations, we show the impact of this effect on the acquired data and provide guidelines for optimal experimental configurations.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2023)
Article
Chemistry, Physical
Matias Herran, Sabrina Juergensen, Moritz Kessens, Dominik Hoeing, Andrea Koeppen, Ana Sousa-Castillo, Wolfgang J. Parak, Holger Lange, Stephanie Reich, Florian Schulz, Emiliano Cortes
Summary: The researchers present a two-dimensional bimetallic catalyst for efficient hydrogen generation under visible light illumination and solar irradiance by incorporating platinum nanoparticles into a well-defined supercrystal of gold nanoparticles. They observe a correlation between the intensity of the electric field in the hotspots and the boosted catalytic activity of platinum nanoparticles, while identifying a minor role of heat and gold-to-platinum charge transfer in the enhancement.
