Article
Chemistry, Multidisciplinary
Eugenii Evropeitsev, Dmitrii Nechaev, Valentin Jmerik, Yuriy Zadiranov, Marina Kulagina, Sergey Troshkov, Yulia Guseva, Daryia Berezina, Tatiana Shubina, Alexey Toropov
Summary: GaN/AlN heterostructures with thicknesses of one monolayer are considered to be the most promising material for UVC light-emitting devices. However, the intrinsic properties of these excitons are masked by fluctuations in the quantum wells' thicknesses. In this work, cylindrical nanocolumns were fabricated to reduce this effect, and it was found that excitons were localized on potential fluctuations attributed to GaN clusters. The emission dynamics were also found to be temperature-dependent.
Article
Materials Science, Multidisciplinary
Suman Chatterjee, Sarthak Das, Garima Gupta, Kenji Watanabe, Takashi Taniguchi, Kausik Majumdar
Summary: Monolayers of semiconducting transition metal dichalcogenides offer a promising platform for exploring many-body physics, and in this study, controlled kinetic manipulation of the charged biexciton was demonstrated through systematic dependence on excitation conditions.
Article
Chemistry, Multidisciplinary
Ying Tang, Qilin Qin, Hongyu Yang, Shengnan Feng, Chunfeng Zhang, Jiayu Zhang, Min Xiao, Xiaoyong Wang
Summary: This study demonstrates the ability to decrease the Auger decay and radiative rates in semiconductor nanocrystals by applying external electric fields. The decrease in the Auger rate is attributed to enhanced exciton-exciton repulsion, while the decrease in the radiative rate is attributed to weakened electron-hole exchange interaction. These findings highlight the potential of using external electric fields as a post-synthetic approach to manipulate the exciton recombination dynamics in semiconductor nanocrystals.
Article
Materials Science, Multidisciplinary
S. Andreev
Summary: The paper discusses quantum phase transitions in a system of bright dipolar excitons. It reveals that at sufficiently large density, an exciton superfluid transforms into a superfluid of biexcitons, accompanied by a reduction in photoluminescence intensity. The formation of a BCS-like biexciton condensate induces correlated alignment of the effective magnetic fields and excitonic spins, presenting important differences from the phenomenon of spin-orbit-coupled Bose-Einstein condensation.
Article
Chemistry, Physical
Goutam Ghosh, Kritiman Marjit, Srijon Ghosh, Amitava Patra
Summary: We investigate the fast hot-carrier (HC) relaxation and Auger recombination (AR) rates in hexapod CsPbBr3 NCs using ultrafast transient absorption (TA) spectroscopy. Our results show that hexapod CsPbBr3 has a prolonged HC cooling time and bi-exciton lifetime compared to cubic CsPbBr3. By employing the electron-phonon coupling model, we confirm the slower HC relaxation rate in hexapod CsPbBr3, suggesting a delayed decay of longitudinal optical (LO) phonons. We demonstrate that delocalization of charge carriers in shallow trap states leads to reduced overlap of electron and hole wave functions and suppresses the bi-exciton AR rate.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Yuri Y. Bleyan, Paytsar A. Mantashyan, Eduard M. Kazaryan, Hayk A. Sarkisyan, Gianluca Accorsi, Sotirios Baskoutas, David B. Hayrapetyan
Summary: This study presents a theoretical investigation of exciton and biexciton states in a strongly oblate ellipsoidal quantum dot made from GaAs. The study analyzes the energy levels, oscillator strength, optical susceptibilities, and absorption coefficients of the quantum dot.
Article
Chemistry, Physical
Go Yumoto, Yoshihiko Kanemitsu
Summary: Lead halide perovskite nanocrystals have gained considerable attention as next-generation optoelectronic materials. This article summarizes recent advances in the photophysics of excitons and biexcitons in these nanocrystals. Understanding their dynamics is crucial for optimal design of optoelectronic devices and the development of new functional properties.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Physics, Condensed Matter
Abeer Abdullah Al Anazi, Anupong Wongchai, M. Abdulfadhil Gatea, Rasha Fadhel Obaid, Karina Silvana Gutierrez Valverde
Summary: In this paper, the transfer of orbital angular momentum (OAM) between applied lights is studied through biexciton coherence and exciton spin coherence. The quantum dot is manipulated by two control fields that couple to a biexciton state, leading to destructive interference, while a weak probe light interacts with one of the ground-level exciton transitions. In this scenario, a new weak signal light can be generated via the four-wave mixing (FWM) mechanism in a second ground-level exciton transition. The role of exciton spin relaxation and intensity of coupling lights on the exchange efficiency of the FWM mechanism is examined. The spatially dependent optical effects are also discussed based on the OAM state and azimuthal angle of vortex light.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Jayanta Dana, Tal Binyamin, Lioz Etgar, Sanford Ruhman
Summary: Transient absorption measurements were conducted on CsPbBr3 nanocrystals within the regime of strong quantum confinement. Results show that a single exciton completely bleaches the band edge absorption peak and induces a new absorption, while the addition of a second exciton bleaches the blue-induced absorption band without producing net stimulated emission.
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
Physics, Condensed Matter
Nguyen Hong Quang, Nguyen Que Huong, Tran Anh Dung, Hoang Anh Tuan, Nguyen Toan Thang
Summary: Theoretical study on excitonic systems localized in a single InAs/GaAs parabolic quantum dot using unrestricted Hartree-Fock method reveals that under strong confinement, the binding energy of quadrons is positive while the binding energy of biexcitons is negative. This suggests that strong lateral confinement in the parabolic quantum dot favors the formation of quadrons rather than biexcitons.
PHYSICA B-CONDENSED MATTER
(2021)
Article
Optics
Anthonin Delphan, Maxim N. Makhonin, Tommi Isoniemi, Paul M. Walker, Maurice S. Skolnick, Dmitry N. Krizhanovskii, Dmitry V. Skryabin, Jean-Francois Carlin, Nicolas Grandjean, Raphael Butte
Summary: We observed polariton lasing in micro-ring resonators based on GaN/AlGaN slab waveguides in the UV spectral range, with stimulated polariton relaxation into multiple ring resonator modes. The strong exciton-photon coupling regime was confirmed by the reduction of the free spectral range and the blueshift of the exciton-like modes with increasing pulse energy. The absence of broadening in the exciton emission further confirmed lasing at low electron-hole densities. Overall, our work paves the way for the development of novel UV devices based on high-speed slab waveguide polariton geometry operating up to room temperature and integrated into complex photonic circuits.
Article
Crystallography
Jing Zhou, Peng Chen, Zili Xie, Xiangqian Xiu, Dunjun Chen, Ping Han, Yi Shi, Rong Zhang, Youdou Zheng
Summary: This paper investigates the behavior of exciton radiative recombination in a GaN-based triangular-like ridge cavity at room temperature. The results show a clear modulation of the spontaneous emission and the presence of a new transition channel in the microcavity, with the effect depending on the angle. Furthermore, changing the tilt angle reveals that the coupling between excitons and photons is strongest at a tilt angle of 10 degrees.
Article
Nanoscience & Nanotechnology
Andreas Liudi Mulyo, Anjan Mukherjee, Ida Marie Hoiaas, Lyubomir Ahtapodov, Tron Arne Nilsen, Havard Hem Toftevaag, Per Erik Vullum, Katsumi Kishino, Helge Weman, Bjorn-Ove Fimland
Summary: This study successfully demonstrates the fabrication of flip-chip ultraviolet light-emitting diodes based on self-assembled GaN/AlGaN nanocolumns, using single-layer graphene as both a growth substrate and a transparent conducting electrode. The high crystalline quality of the nanocolumns and the presence of intrinsic GaN quantum disk are confirmed through detailed electron microscopy characterization. The optical emission characteristics reveal the absence of defect-related yellow emission and the presence of blue-shifted emission, attributed to quantum confinement and strain effects.
ACS APPLIED NANO MATERIALS
(2021)
Article
Energy & Fuels
Weidong Zhang, Tyler A. Growden, Paul R. Berger, David F. Storm, David J. Meyer, Elliott R. Brown
Summary: The study investigates the electroluminescence phenomenon in unipolar-doped GaN/AlN/GaN double-barrier heterostructures without p-type contacts, showing changes in photon energy characteristics at different temperature ranges and confirming the emission source as excitonic radiative recombination.
Article
Materials Science, Multidisciplinary
Manoj Kumar, Hiroto Sekiguchi, Hiroshi Okada, Akihiro Wakahara
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2013)
Article
Engineering, Electrical & Electronic
Hiroshi Okada, Yuki Okada, Hiroto Sekiguchi, Akihiro Wakahara, Shin-ichiro Sato, Takeshi Ohshima
IEICE TRANSACTIONS ON ELECTRONICS
(2014)
Article
Physics, Applied
ChangYong Lee, Hiroto Sekiguchi, Hiroshi Okada, Akihiro Wakahara
JAPANESE JOURNAL OF APPLIED PHYSICS
(2012)
Article
Physics, Applied
Sang-Baie Shin, Hiroto Sekiguchi, Hiroshi Okada, Akihiro Wakahara
JAPANESE JOURNAL OF APPLIED PHYSICS
(2013)
Article
Physics, Applied
Hiroto Sekiguchi, Yasufumi Takagi, Tatsuki Otani, Ryota Matsumura, Hiroshi Okada, Akihiro Wakahara
JAPANESE JOURNAL OF APPLIED PHYSICS
(2013)
Article
Physics, Applied
Hiroto Sekiguchi, Yasufumi Takagi, Tatsuki Otani, Hiroshi Okada, Akihiro Wakahara
JOURNAL OF APPLIED PHYSICS
(2013)
Article
Optics
Akihiro Wakahara, Hiroto Sekiguchi, Hiroshi Okada, Yasufumi Takagi
JOURNAL OF LUMINESCENCE
(2012)
Article
Engineering, Electrical & Electronic
Manoj Kumar, Chang Yong Lee, Hiroto Sekiguchi, Hiroshi Okada, Akihiro Wakahara
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2013)
Article
Physics, Applied
Hiroto Sekiguchi, Masaru Sakai, Takuho Kamada, Keisuke Yamane, Hiroshi Okada, Akihiro Wakahara
JOURNAL OF APPLIED PHYSICS
(2019)
Article
Crystallography
Hiroto Sekiguchi, Kohei Date, Tomohiko Imanishi, Hiroki Tateishi, Keisuke Yamane, Hiroshi Okada, Katsumi Kishino, Akihiro Wakahara
JOURNAL OF CRYSTAL GROWTH
(2019)
Article
Crystallography
Jose A. Piedra-Lorenzana, Keisuke Yamane, Koki Shiota, Junya Fujimoto, Shunsuke Tanaka, Hiroto Sekiguchi, Hiroshi Okada, Akihiro Wakahara
JOURNAL OF CRYSTAL GROWTH
(2019)
Article
Materials Science, Multidisciplinary
Hiroshi Okada, Kiyomasa Miwa, Taichi Yokoyama, Keisuke Yamane, Akihiro Wakahara, Hiroto Sekiguchi
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2020)
Article
Physics, Applied
Hiroto Sekiguchi, Hayate Matsuhira, Ryota Kanda, Shuto Tada, Taiki Kitade, Masataka Tsutsumi, Atsushi Nishikawa, Alexander Loesing, Izumi Fukunaga, Susumu Setogawa, Noriaki Ohkawa
Summary: In this study, a biocompatible optical stimulation device was developed that can adhere to the brain surface and activate spatially separated brain regions. By using a hollow structure and a thermal release sheet, microLEDs were successfully transferred onto a biocompatible parylene film without any rotation or misalignment while retaining their characteristics.
APPLIED PHYSICS EXPRESS
(2022)
Article
Nanoscience & Nanotechnology
Tomohiro Okuno, Ryota Onoda, Lisa Toyoshima, Kasumi Miyata, Hiroto Sekiguchi, Akihiro Wakahara, Toshihiro Nakaoka
Summary: The study investigates the strain-dependent g-factors of Eu3+ centers in GaN: Eu thin films and finds a correlation between the effective g-factor and the emission energy shift induced by local strain. The research suggests that the g-factor can be tuned by local strain, providing a method to access individual spins.
Article
Optics
Hiroki Yasunaga, Hibiki Takeuchi, Koyo Mizuguchi, Atsushi Nishikawa, Alexander Loesing, Mikiko Ishikawa, Chikako Kamiyoshihara, Susumu Setogawa, Noriaki Ohkawa, Hiroto Sekiguchi
Summary: This study investigates the temperature rise characteristics in brain tissue using a MicroLED probe. The findings show that the temperature rise strongly depends on the surrounding environment and the area of contact. Additionally, a new method for in situ temperature monitoring using the electrical characteristics of the MicroLED is proposed. Furthermore, the study demonstrates the effective control of optogenetic neural activity through optical stimulation by MicroLEDs.
Article
Optics
R. B. Adamov, G. A. Melentev, I. V. Sedova, S. V. Sorokin, G. V. Klimko, I. S. Makhov, D. A. Firsov, V. A. Shalygin
Summary: This study investigates the THz luminescence in doped nanostructures with GaAs/AlGaAs quantum wells under interband optical pumping. The results show that the spatial separation of donors and acceptors can greatly enhance the integrated intensity of THz emission.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Yanru Li, Lei Zhong, Sha Jiang, Yutong Wang, Binyao Huang, Guotao Xiang, Li Li, Yongjie Wang, Chuan Jing, Xianju Zhou
Summary: In this study, a ratiometric luminescent thermometry based on dual-emission centers was developed using co-doped CaNb2O6 phosphors with Bi3+ and Pr3+. The obtained samples exhibited good thermosensitive and thermochromic characteristics, with a maximum absolute sensitivity of 0.09 K-1 @ 528 K and a maximum relative sensitivity of 2.17 % K-1 @ 453 K.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Yujing Gong, Yeqing Wang, Zhiyuan Wang, Yijian Sun, Yi Yu
Summary: Single crystals of Dy3+ single-doped and Dy3+/Tb3+ co-doped CaYAlO4 were grown and analyzed. The incorporation of Tb3+ resulted in increased absorption and emission cross sections. The fluorescence lifetimes and branching ratios of the yellow emission were affected by the presence of Tb3+. The deactivation effect of Tb3+ ions and energy transfer mechanism were also discussed.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Lu Chen, Zhuangzhuang Ma, Jian Chen, Wang Guo
Summary: This study focuses on enhancing the thermal robustness of phosphor converter materials by preparing composite ceramics of YAG:Ce combined with high-thermal-conductivity MgO. The composite ceramics showed high density and thermal conductivity at the optimum temperature of 1400℃. Stable laser-driven white light was obtained under blue laser excitation.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Yuwei Wu, Chunhui Niu, Lei Wang, Mingqing Yang, Shiyu Zhang
Summary: Er3+-doped germanate-tellurite glasses were prepared and their structure, luminescent, and temperature-sensing properties were studied. The glass exhibited large values of O2 and O6 and its luminescence intensity varied with temperature.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Kensei Ichiba, Takumi Kato, Kenichi Watanabe, Yuma Takebuchi, Daisuke Nakauchi, Noriaki Kawaguchi, Takayuki Yanagida
Summary: In this study, Eu-doped YVO4 single crystals with different concentrations were fabricated to evaluate their photoluminescence and scintillation properties. The results showed that the samples doped with Eu exhibited emission peaks due to 4f-4f transitions in PL and scintillation spectra. Based on the pulse height spectra, the light yield of the Eu-doped samples increased with increasing Eu concentration, while the afterglow level decreased.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Daiwen Xiao, Hei-Yui Kai, Anjun Huang, Menglin Song, Ka-Leung Wong, Peter A. Tanner
Summary: The emission spectra of Cs2NaEuCl6 nanoparticles synthesized by the hot injection method are explained. The dispersion of the nanoparticles in alkane solvents in the experiment allows the determination of the magnetic dipole radiative rate for the D-5(0) -F-7(1) channel in vacuum, which is in agreement with the calculated value.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Italia V. Barbosa, Geraldine Dantelle, Alain Ibanez, Lauro J. Q. Maia
Summary: The thermal response and luminescence properties of different oxide matrices were evaluated to design more accurate thermal probes. It was found that thermal probes emitting in BW-II provide better thermal sensing with higher signal-to-noise ratio. Additionally, doping Nd3+ in Y2O3 matrix maximizes luminescence intensity, making it a promising matrix for thermal sensing.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Xin Li, Yu Zhang, Hongrui Ren, Lunlong Xie, Yinsheng Di, Mengqing Han, Zhaohui Bai, Quansheng Liu, Liangliang Zhang, Jiahua Zhang
Summary: This study successfully prepared phosphor samples based on Ca3-xLuxSc2-xMgxSi3O12:Ce3+ and investigated their luminescence properties. With the increase in Lu-Mg concentration, the peak of the sample redshifted, but the thermal stability gradually decreased. The LD devices made from CLSMS:Ce3+ fluorescent materials showed a decrease in cyan-green light and an increase in red light as the Lu-Mg concentration increased.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Tim Pier, Julia Hopster, Thomas Juestel
Summary: This study investigates and reports on several samples of cerium-activated gallium-based garnet phosphors. The optimal activator concentration was found to be 1 atom-%. The size of non-emitting lanthanide ions and the molar concentration of cerium strongly influenced the crystal field splitting, which in turn shaped the excitation and emission wavelengths.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Guijie Zhao, Wei Shi, Xin Xin, Fengcai Ma, Yongqing Li
Summary: This study reveals for the first time the proton transfer pathways and changes in the photophysical properties of P-TNS with three intramolecular hydrogen bonds. The reaction mechanism and driving force for the proton transfer process are explained through analysis of potential energy surface, frontier molecular orbitals, and hydrogen bond parameters, among others.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Li He, Jinshu Huang, Zhengce An, Haozhang Huang, Yu Zhao, Kexin Zhong, Bo Zhou
Summary: In this study, we designed a NaYF4:Yb3+/Tm3+@NaYF4 core-shell nanostructure to achieve thermochromic upconversion and high thermal sensitivity. We found that the blue upconversion emission of Tm3+ decreased while the deep-red emission increased with elevating temperature. The sample also showed a gradual emission color change from blue to purplish-red, and the optimal relative sensitivity reached 2.79% K-1.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Rupesh A. Talewar
Summary: A series of Li2TiO3 phosphors doped with Mn4+ and codoped with Mn4+ and Er3+ were synthesized, which demonstrated the ability of Mn4+ ions to absorb UV-Vis photons and subsequently transfer energy to Er3+ ions, resulting in the emission of near-infrared light. These materials have the potential to enhance the absorption efficiency of Er3+-based luminescent materials.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
Xingyuan Ma, Jianfeng Li
Summary: Carbon quantum dots (CQDs) with tunable photoluminescence properties have been synthesized using suitable carbon and dopant sources in an aqueous system. The synthesized CQDs exhibited blue, green, yellow, and red emissions, and solid-state luminescence was achieved through the preparation of solid-state fluorescent films and phosphors. This study provides important technical support for the future development of CQDs synthesis.
JOURNAL OF LUMINESCENCE
(2024)
Article
Optics
De Bin Fu, Yang Bing Xu, Yu Teng Zhang, Shan Ting Liu, Xiao Fei Yang, Sheng Hua Liu
Summary: A pair of new chiral molecules, (S)-4 and (R)-4, have been designed and synthesized by introducing valine-containing groups at symmetrical positions on the periphery of an indolo[3,2-b]carbazole unit. These molecules exhibit aggregation-induced circular dichroism (AICD) properties in DMF/water mixtures, and in a mixture with 99% water fraction, they show strong, mirror-image, blue circularly polarized luminescence (CPL) signals.
JOURNAL OF LUMINESCENCE
(2024)
