Article
Chemistry, Physical
Lifeng Wang, Dongmei Xiang, Kaimin Gao, Junhui Wang, Kaifeng Wu
Summary: Colloidal n-doped CdSe and CdSe/ZnS nanoplatelets have been achieved through a photochemical doping method, demonstrating successful additional electron doping at the conduction band edge. The key to successful doping lies in a high surface ligand coverage, while unpassivated surface cations may lead to depletion of the doped electrons.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Physical
Dongmei Xiang, Yulu Li, Lifeng Wang, Tao Ding, Junhui Wang, Kaifeng Wu
Summary: In this study, the electron and hole spin dynamics in CdSe colloidal nanoplatelets of varying thicknesses were investigated using circularly polarized transient absorption spectroscopy. The results showed that hole spin-flip occurred within 200 fs, while the electron spin lifetime decreased as the platelet thickness was reduced. The findings suggest an exchange interaction between the electron and the hole, and/or surface dangling bond spins enhanced by quantum confinement.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Andrew A. Marder, James Cassidy, Dulanjan Harankahage, Jacob Beavon, Luis Gutierrez-Arzaluz, Omar F. Mohammed, Aditya Mishra, Austen C. Adams, Jason. D. Slinker, Zhongjian Hu, Stephen Savoy, Mikhail Zamkov, Anton V. Malko
Summary: Compared to zero-dimensional (0D) semiconductor quantum dots, 2D semiconductor nanoplatelets (NPLs) offer a spectrally narrow luminescence and superior absorption coefficients. However, optical devices based on NPLs still suffer from nonradiative Auger decay, which limits the efficiency of various processes. In this study, it is demonstrated that Auger recombination is strongly suppressed in spherically shaped nanoplatelets called quantum shells (QSs), leading to improved performance in terms of biexciton emission yield, amplified spontaneous emission, and electroluminescence enhancement. These results are significant for the development of solution-processed colloidal lasers and LEDs.
ACS MATERIALS LETTERS
(2023)
Article
Chemistry, Physical
Z. Ouzit, G. Baillard, J. Liu, B. Wagnon, L. Guillemeney, B. Abecassis, L. Coolen
Summary: This study compares the luminescence decay dynamics of single CdSe nanoplatelets, clusters of a few platelets, and self-assembled chains. The luminescence decay becomes faster as the number of stacked platelets increases, indicating the FRET-mediated effect of quenchers. Additionally, a slow decay component is observed for both single platelets and platelet chains, suggesting trapping-detrapping mechanisms in nearby trap states. Toy models are developed to analyze the effects of FRET-mediated quenching and trapping on decay curves.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Alexander M. Smirnov, Anastasia D. Golinskaya, Vladimir N. Mantsevich, Maria Kozlova, Kseniia V. Ezhova, Bedil M. Saidzhonov, Roman B. Vasiliev, Vladimir S. Dneprovskii
Summary: Experimental investigations were conducted on the transient absorption of colloidal heterostructured CdSe/CdS nanoplatelets under high-intensity nanosecond laser pulses, revealing a strong dependence on nanoplatelets concentration and pump intensities. Nonlinear transmission changes in nanoplatelets solutions were explained by various factors, and the identification of conditions for optical gain in colloidal solutions was a significant result.
RESULTS IN PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Avisek Dutta, Anusri Medda, Soubhik Ghosh, Sumanta Sain, Amitava Patra
Summary: This work highlights the influence of reaction growth time on the properties of cadmium chalcogenide nanoplatelets, with a focus on structural and photophysical aspects. By extending the growth time, improvements in photoluminescence emission and decay time have been achieved, as well as slower dynamics in bleach recovery. The CdSe/CdS CS NPLs-based photodetectors show promising performance for next-generation optoelectronic applications.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Huan Liu, Peixian Chen, Xuanyu Zhang, Xiongbin Wang, Tingchao He, Rui Chen
Summary: Two-dimensional colloidal CdSe nanoplatelets (NPLs) with different structures were synthesized and their optical properties were characterized. It was found that the photoluminescence quantum yield of the NPLs improved significantly after the growth of the CdS crown layer. The emission intensity ratio at low temperatures suggested that the radiative recombination centers were mainly located on the lateral surface, which was confirmed by surface passivation experiment. Additionally, the ligand exchange experiment confirmed the presence of nonradiative recombination centers on the lateral surface. These findings highlight the importance of understanding the optical properties of the lateral surface of NPLs for optoelectronic applications.
Article
Chemistry, Physical
Nina N. Kurus, Alexander G. Milekhin, Roman Sklyar, Bedil M. Saidzhonov, Roman B. Vasiliev, Sergei Adichtchev, Nikolai Surovtsev, Alexander Latyshev, Dietrich R. T. Zahn
Summary: The phonon spectra of core/shell CdSe/CdS nanoplatelets with different shell thicknesses were studied, revealing frequency shifts of optical modes as the shell thickness increases, which can be explained in terms of the stress state in the core and shell, as well as the influence of phonon confinement.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Alexander Lebedev, Bedil M. Saidzhonov, Konstantin A. Drozdov, Andrey A. Khomich, Roman B. Vasiliev
Summary: The vibrational spectroscopy of semiconductor nanostructures can provide important information regarding their structure. In this study, experimental and calculated vibrational spectra of CdSe/CdS core/shell nanoplatelets were compared, revealing the phonon behavior and surface atomic vibration relaxation in nanostructures. The results indicate a noticeable surface relaxation of the outer Cd layer in the nanostructure, affecting the thickness dependence of certain modes.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Alexandra Brumberg, Nicolas E. Watkins, Benjamin T. Diroll, Richard D. Schaller
Summary: Colloidal semiconductor nanocrystals, such as CdSe nanoplatelets and quantum dots, offer advantages in optoelectronics but are affected by rapid nonradiative Auger recombination at high excitation intensities. This study investigates the temperature dependence of excited state lifetime and fluence-dependent emission, revealing fundamental differences between CdSe nanoplatelets and core-only quantum dots, and highlighting the increased utility of photogenerated excitons and multiexcitons at low temperatures.
Article
Optics
I. D. Laktaev, B. M. Saidzhonov, R. B. Vasiliev, A. M. Smirnov, O. V. Butov
Summary: The photoluminescence features of a light-hole - electron exciton transition in CdSe/CdS nanoplatelets colloidal solution under resonant two-photon excitation were investigated. The powerlaw dependence of the photoluminescence intensity on the excitation laser femtosecond pulses intensity was discovered to be related to biexciton radiation. In addition, the conditions for the photoluminescence growth and quenching were determined based on the concentration and pump intensity.
JOURNAL OF LUMINESCENCE
(2022)
Article
Chemistry, Multidisciplinary
Hongyu Yang, Lei Zhang, Wenbin Xiang, Changgui Lu, Yiping Cui, Jiayu Zhang
Summary: In this study, room-temperature exciton-polariton Bose-Einstein condensation was achieved and the realization of polariton laser was confirmed. Colloidal nanoplatelets show great prospects in low-cost, high-performance polariton devices and coherent light sources.
Article
Chemistry, Multidisciplinary
Olga O. Smirnova, Ina V. Kalitukha, Anna V. Rodina, Grigorii S. Dimitriev, Victor F. Sapega, Olga S. Ken, Vladimir L. Korenev, Nikolai V. Kozyrev, Sergey V. Nekrasov, Yuri G. Kusrayev, Dmitri R. Yakovlev, Benoit Dubertret, Manfred Bayer
Summary: This study investigates the optical alignment and orientation of excitons in colloidal nanoplatelets and evaluates their properties through theoretical analysis and experimental data.
Article
Chemistry, Multidisciplinary
Carmelita Roda, Alessio Di Giacomo, Lucia Camila Tasende Rodriguez, M. Chandra Sekhar, Jari Leemans, Zeger Hens, Pieter Geiregat, Iwan Moreels
Summary: We synthesized CdSe/CdS nanoplatelets with 3.5 monolayers, which exhibit saturated blue emission and high photoluminescence quantum efficiency (PL QE) up to 55%. Compared to core-only nanoplatelets, the PL intensity decays exponentially due to suppressed deep trapping and delayed emission. Both core-only and core/crown nanoplatelets show biexciton-mediated optical gain between 470 and 510 nm, with higher gain coefficients in crowned nanoplatelets. However, the gain lifetimes are limited to 40 ps due to residual ultrafast trapping and higher exciton densities at threshold. These findings provide guidelines for optimizing CdSe nanoplatelets for lighting and light-amplification applications.
Article
Chemistry, Physical
Yonglei Sun, Hua Zhu, Na Jin, Ou Chen, Jing Zhao
Summary: Lifetime blinking, a phenomenon of fluctuations in the fluorescence lifetime of a single quantum dot over time while its fluorescence intensity remains relatively stable, has been reported in a few QD systems. In this study, statistical methods demonstrate that compact CdSe/CdS core/shell QDs also exhibit short-lived lifetime blinking events, possibly due to the activation of efficient nonradiative processes leading to intensity blinking.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Materials Science, Multidisciplinary
Leonie Gomell, Tobias Haeger, Moritz Roscher, Hanna Bishara, Ralf Heiderhoff, Thomas Riedl, Christina Scheu, Baptiste Gault
Summary: The microstructure of a material plays an important role in its thermoelectric performance. In this study, the researchers investigated the microstructure and local properties of the Heusler-Fe2VAl compound using advanced microscopy techniques. They found that laser surface remelting can be used to manipulate the microstructure, leading to improved thermoelectric performance at room temperature.
Article
Materials Science, Multidisciplinary
Thomas Riedl, Joerg K. N. Lindner
Summary: An automated analysis method for SEM images was developed in this study to efficiently recognize and quantify the size of nanospheres, mask openings, and sphere-sphere separations in colloidal nanosphere monolayers, providing important technical support for cost-effective patterning.
MICROSCOPY AND MICROANALYSIS
(2022)
Article
Materials Science, Multidisciplinary
A. Mayer, T. Haeger, M. Runkel, J. Staabs, J. Rond, F. van Gen Hassend, P. Goerrn, T. Riedl, H-C Scheer
Summary: Promising new materials like solution-processable perovskites may provide devices with superior properties. This study focuses on the organic-inorganic perovskite methylammonium lead bromide (MAPbBr(3)) and investigates its imprinting process. The results show that starting with a large-grained layer is optimal for replicating micro/nano-structures. Analogies with thermoplastic polymers are used to understand the shaping process of polycrystalline perovskites, and it is discovered that grain size and shape can be controlled by the imprinted pattern.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Chantal Martin, Anatol Prudnikau, Leonardo Orazi, Nikolai Gaponik, Vladimir Lesnyak
Summary: A new approach is proposed to directly form red-emitting perovskite nanocrystals in a polymer matrix through anion exchange. Green-emitting templates and iodine source are used, and photo-assisted termination reaction is demonstrated to control the optical properties. The findings enable the selective generation of green- and red-emitting features with high resolution on a thin film using an ultrashort UV laser.
ADVANCED OPTICAL MATERIALS
(2022)
Editorial Material
Nanoscience & Nanotechnology
Peter Muller-Buschbaum, Thomas Riedl
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Ankita Bora, Anatol Prudnikau, Ningyuan Fu, Rene Huebner, Konstantin B. L. Borchert, Dana Schwarz, Nikolai Gaponik, Vladimir Lesnyak
Summary: The article introduces a method for synthesizing luminescent In-rich Cu-Zn-In-S NPLs using a one-pot approach, and successfully prepares quaternary NPLs with improved stability and optical properties.
CHEMISTRY OF MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Tim Hasselmann, Bujamin Misimi, Nils Boysen, David Zanders, Jan-Lucas Wree, Detlef Rogalla, Tobias Haeger, Florian Zimmermann, Kai Oliver Brinkmann, Sebastian Schaedler, Detlef Theirich, Ralf Heiderhoff, Anjana Devi, Thomas Riedl
Summary: In this study, highly conductive silver films were successfully grown at low temperatures using plasma-enhanced spatial ALD with a newly introduced nitrogen-based silver precursor. These silver films, used as bottom electrodes in organic solar cells, showed comparable performance to those made by traditional high-temperature vacuum processes.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Chemistry, Physical
Artsiom Antanovich, Lan Yang, Steven C. Erwin, Beatriz Martin-Garcia, Rene Huebner, Christine Steinbach, Dana Schwarz, Nikolai Gaponik, Vladimir Lesnyak
Summary: Cadmium chalcogenide nanoplatelets (NPLs) are promising materials for optoelectronic applications, but their thickness tuning is limited. This study overcomes this limitation by using highly reactive chalcogen sources to achieve precise control over the thickness of alloyed CdSexS1-x NPLs.
CHEMISTRY OF MATERIALS
(2022)
Article
Physics, Applied
Thomas Riedl, Vinay S. Kunnathully, Akshay K. Verma, Timo Langer, Dirk Reuter, Bjoern Bueker, Andreas Huetten, Joerg K. N. Lindner
Summary: A process for the large-area fabrication of nanopillar-patterned semiconductor templates for selective-area heteroepitaxy has been developed. The growth of defect-free nanoscale InAs islands on the nanopillar tops has been observed using electron microscopy.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Condensed Matter
Falco Meier, Mario Littmann, Julius Buerger, Thomas Riedl, Daniel Kool, Joerg Lindner, Dirk Reuter, Donat Josef As
Summary: In this study, the researchers investigated the possibility of nanoselective area growth (NSAG) of cubic gallium nitride on 3C-SiC/Si (001) pseudo substrates. The growth was controlled by SiO2 patterns. Nanosphere lithography and block-copolymer lithography were used to create patterned holes. It was demonstrated that pure phase nucleation of cubic gallium nitride could be achieved on the surface and facets of 3C-SiC. High-resolution X-ray diffraction measurements confirmed a hexagonal fraction on a macroscopic scale. Furthermore, the researchers showed the possibility of coalescence with the dominant cubic phase after NSAG.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2022)
Article
Chemistry, Physical
Jarla Thiesbrummel, Francisco Pena-Camargo, Kai Oliver Brinkmann, Emilio Gutierrez-Partida, Fengjiu Yang, Jonathan Warby, Steve Albrecht, Dieter Neher, Thomas Riedl, Henry J. Snaith, Martin Stolterfoht, Felix Lang
Summary: Understanding the performance losses in all-perovskite tandem photovoltaics is crucial for advancing toward commercialization. This study characterizes the individual sub-cells in all-perovskite tandem stacks and shows that non-radiative losses dominate the overall recombination. Through various approaches, the open-circuit voltage of the high-gap perovskite subcell is enhanced, leading to improved efficiency in all-perovskite tandem solar cells.
ADVANCED ENERGY MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Ye Yu, Anatol Prudnikau, Vladimir Lesnyak, Robert Kirchner
Summary: In the past two decades, direct laser writing (DLW) technologies have experienced significant growth, but there is still a lack of strategies to enhance printing resolution and develop materials with diverse functionalities. This study presents a cost-effective method to address this bottleneck by utilizing semiconductor quantum dots (QDs) through surface chemistry modification. The evaluations showed that QDs exhibited excellent colloidal stability and preserved photoluminescent properties, enabling further exploration of the printing characteristics of the composite material.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Charles Otieno Ogolla, Yannik Loth, Tobias Haeger, Cedric Kreusel, Manuel Runkel, Thomas Riedl, Benjamin Butz, Anna Katharina Wigger, Stephan Schaeffer, Peter Haring Bolivar
Summary: In this study, THz-sSNOM was used for nanoscale imaging of CsPbBr3 thin films, and the local THz nanoscale conductivity was derived using a scattering model. The analysis of the obtained signals confirmed the presence of halide vacancies (VBr) and Pb-Pb bonds at the CsPbBr3 grain boundaries, which resulted in charge carrier trapping and nonradiative recombination. This study establishes THz-sSNOM as a powerful analysis platform for thin-film semiconductors like LHPs.
Article
Chemistry, Multidisciplinary
Liudmila Trotsiuk, Alina Muravitskaya, Artur Movsesyan, Andrei Ramanenka, Anatol Prudnikau, Artsiom Antanovich, Vladimir Lesnyak, Sergey V. Gaponenko, Alexander O. Govorov
Summary: This article investigates the metal-enhanced photoluminescence phenomenon of semiconductor nanocrystals under nonplasmonic conditions and correlates it with charge exchange processes. The study found that injecting holes into semiconductor nanocrystals can increase the photoluminescence intensity.
Article
Computer Science, Information Systems
Utpal Kalita, Christian Tueckmantel, Thomas Riedl, Ullrich R. Pfeiffer
Summary: This paper presents a multi-finger doubler based on amorphous-indium gallium zinc oxide (a-IGZO) thin film transistors (TFT) operating at GHz frequency. The doubler and the TFTs have been fabricated in-house with chromium (Cr) gate electrodes. The device output power, the threshold voltage mismatch, and breakdown characteristics are explained with the help of the model. The peak second harmonic conversion gain of the doubler is measured to be -32 dB at a gate overdrive voltage of around 2.8 V for a 500 MHz input signal. This second harmonic output frequency exceeds the TFT's transit and maximum oscillation frequencies.