Article
Materials Science, Multidisciplinary
Raquel Esteban-Puyuelo, Biplab Sanyal
Summary: This study systematically investigated the role of point defects in the recombination time of monolayer MoS2, demonstrating that defects significantly accelerate electron-hole recombination, especially interstitial S atoms. Mo defects introduce multiple de-excitation pathways via various defect levels in the energy gap, providing fundamental understanding of photoinduced de-excitation dynamics in 2D MoS2 with defects.
Article
Chemistry, Physical
Vinod K. Rajput, Dipak Maity, Bedanta K. Deka, Tharangattu N. Narayanan, Sri Ram G. Naraharisetty
Summary: Scientists study the carrier dynamics of 3-4 layered MoS2 using ultrafast visible pump and mid-IR probe spectroscopy, revealing the significant role of defect states in the optoelectronic properties of the material.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Tanmay Goswami, Himanshu Bhatt, K. Justice Babu, Gurpreet Kaur, Nandan Ghorai, Hirendra N. Ghosh
Summary: This study employed transient absorption spectroscopy to investigate the optical processes related to different excitonic features in few layer WS2, a TMDC representative. It revealed a strong intervalley coupling across the momentum space and slower dynamics for C and D excitons compared to A and B excitons. All four excitons were observed to emerge in the system and influence each other, regardless of the incident photon energy.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Naseem Ud Din, Volodymyr Turkowski, Talat S. Rahman
Summary: The interplay of ultrafast charge dynamics and electron-phonon interaction in AA' stacked bilayer MoS2 is crucial for understanding the emission spectrum features. The analysis of the wave vector dependencies of the electron-phonon interaction helps trace the higher energy peak in the spectrum.
Article
Chemistry, Physical
Wenyan Wang, Ning Sui, Xiaochun Chi, Zhihui Kang, Qiang Zhou, Li Li, Hanzhuang Zhang, Jianbo Gao, Yinghui Wang
Summary: The hot carrier cooling dynamics in monolayer MoS2 C-excitonic state is affected by the hot phonon bottleneck and Auger heating effects, and can be prolonged by increasing the excitation photon energy or absorbed photon flux. The combination of these effects weakens the hot phonon bottleneck and extends the hot carrier lifetime, which has implications for various applications in advanced energy conversion and quantum technology.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Optics
Susobhan Das, Yadong Wang, Yunyun Dai, Shisheng Li, Zhipei Sun
Summary: This study reports the ultrafast transient absorption of monolayer molybdenum disulfide in its sub-bandgap region, revealing significant absorbance enhancement below the bandgap. The different rise times at different wavelengths indicate various contributions of carrier states, providing insights into optical properties and carrier dynamics for potential photonic and optoelectronic applications beyond intrinsic bandgap limitations.
LIGHT-SCIENCE & APPLICATIONS
(2021)
Article
Chemistry, Physical
Arshdeep Kaur, Tanmay Goswami, Kaliyamoorthy Justice Babu, Hirendra N. Ghosh
Summary: A 1D/0D SnS@CdS heterostructure was successfully synthesized by hot injection method, where CdS QDs were uniformly anchored on the surface of SnS NRs. Photoluminescence and transient absorption studies confirmed the transfer of photoexcited holes and efficient charge separation across the p-n heterojunction. These findings offer a new paradigm for improving the efficiency of optoelectronic devices.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Review
Chemistry, Multidisciplinary
Ravi Kumar Venkatraman, Andrew J. Orr-Ewing
Summary: Photochemical reactions are increasingly used for chemical and materials synthesis, involving photoexcitation of molecular chromophores dissolved in solvent. The choice of solvent influences the outcomes by modifying the energies and crossings between electronic states of chromophores. Ultrafast laser spectroscopy can resolve the dynamics of photoexcited molecules, with femtosecond to picosecond resolution, revealing the influences of solvents on internal conversion and intersystem crossing in nonradiative relaxation pathways. Different solvents can selectively affect the excited-state dynamics, as illustrated by examples of aromatic compounds and sunscreen molecules. Ultimately, understanding how solvents impact photodynamics can help control the outcomes of photochemical reactions.
ACCOUNTS OF CHEMICAL RESEARCH
(2021)
Article
Chemistry, Multidisciplinary
Duan Luo, Jian Tang, Xiaozhe Shen, Fuhao Ji, Jie Yang, Stephen Weathersby, Michael E. Kozina, Zhijiang Chen, Jun Xiao, Yusen Ye, Ting Cao, Guangyu Zhang, Xijie Wang, Aaron M. Lindenberg
Summary: The study utilized ultrafast electron diffraction to simultaneously visualize charge transfer and electron-phonon coupling in MoS2-graphene heterostructures. It was found that the timescale of charge transfer and relaxation varies significantly with twist angle, indicating that twist angle can serve as an additional tuning knob for interlayer charge transfer in heterobilayers. The research deepened the understanding of fundamental photophysical processes in heterostructures, which is important for future applications in optoelectronics and light harvesting.
Article
Chemistry, Multidisciplinary
Yanyu Yin, Xingju Zhao, Xiaoyan Ren, Kun Liu, Jin Zhao, Lili Zhang, Shunfang Li
Summary: In this study, the interlayer carrier dynamics of black phosphorus and MoS2 heterostructure were investigated through simulations. The results showed that the electron and hole transfer time depended on the layer number of black phosphorus, with linear and exponential relationships respectively. These findings provide new insights for improving the ultrafast carrier dynamics process in two-dimensional heterostructures.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Nikhil Tilak, Guohong Li, Takashi Taniguchi, Kenji Watanabe, Eva Y. Andrei
Summary: Artificially twisted heterostructures of semiconducting transition-metal dichalcogenides (TMDs) provide control over their electronic and optical properties via spatial modulation of interlayer interactions and structural reconstruction. This study investigates twisted MoS2 bilayers at twist angles near 0 degrees using scanning tunneling microscopy/spectroscopy. The moire pattern, dominated by lattice reconstruction for small angles, reveals large triangular domains with rhombohedral stacking. Spectroscopy measurements show a strong moire potential for angles below 3 degrees. In reconstructed regions, an asymmetry between neighboring domains is observed, which is attributed to the vertical polarization intrinsic to rhombohedral stacked TMDs. This study offers insights into interfacial ferroelectrics and has implications for designing novel heterostructures harnessing this effect.
Article
Materials Science, Multidisciplinary
Yu Liang, Bo-Han Li, Ziling Li, Guanhua Zhang, Julong Sun, Chuanyao Zhou, Youtian Tao, Yu Ye, Zefeng Ren, Xueming Yang
Summary: This study investigated the ultrafast carrier dynamics of two-dimensional molybdenum disulfide (MoS2) flakes using femtosecond time-resolved micro-area photoelectron spectroscopy and photoemission electron microscopy. Spatial heterogeneity and defect effects were observed, with defects significantly shortening charge carrier lifetime while acting as recombination centers. Three relaxation processes were identified in the photoelectron intensity dynamics, with different rates influenced by defect density and bulk electron transportation. The results deepen the understanding of interfacial carrier dynamics and defect effects on charge carrier lifetime in MoS2 materials.
MATERIALS TODAY PHYSICS
(2021)
Article
Multidisciplinary Sciences
Ke Wang, Gang Xu, Fei Gao, He Liu, Rong-Long Ma, Xin Zhang, Zhanning Wang, Gang Cao, Ting Wang, Jian-Jun Zhang, Dimitrie Culcer, Xuedong Hu, Hong-Wen Jiang, Hai-Ou Li, Guang-Can Guo, Guo-Ping Guo
Summary: Hole-spin qubits in germanium show promise for rapid, all-electrical qubit control. The authors demonstrate ultrafast single-spin manipulation in a hole-based double quantum dot in a germanium hut wire, with a record Rabi frequency exceeding 540 MHz. These results suggest the potential for ultrafast coherent control of hole spin qubits to meet the requirements for scalable quantum information processing.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Neha Nayyar, Duy Le, Volodymyr Turkowski, Talat S. Rahman
Summary: In this study, we investigated the effect of electron-phonon coupling on electron doped monolayer MoS2 using a combination of theoretical methods. The results showed that even with low doping levels, the electron-phonon coupling had a significant impact on the emissive properties and response to femtosecond laser pulses. The monolayer MoS2 also exhibited ultrafast relaxation of the electronic subsystem and high carrier mobility.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Jianbo Hu, Yang Xiang, Beatrice Matilde Ferrari, Emilio Scalise, Giovanni Maria Vanacore
Summary: Transition metal dichalcogenides layered nano-crystals show great potential as next-generation optoelectronic and quantum devices. Understanding the interaction between excitonic states and atomic vibrations is crucial for their fundamental properties. This study investigates the structural dynamics of low-energy indirect excitons in MoS2 following nearly-resonant excitation using ultrafast electron diffraction and ab initio calculations. The results reveal the specific phononic excitations associated with the wavelength-dependent electronic transitions of the system, highlighting their strong selectivity.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Review
Chemistry, Multidisciplinary
Zhihao Zhang, Lu Qiao, Ke Meng, Run Long, Gang Chen, Peng Gao
Summary: Lead halide perovskite solar cells have achieved significant progress in efficiency and stability. This review discusses various passivation strategies to address the challenges of defects, charge recombination, and stability in perovskite materials. The article also highlights the need for advanced characterization techniques to understand the mechanisms behind the passivation strategies, and proposes future research directions.
CHEMICAL SOCIETY REVIEWS
(2023)
Article
Chemistry, Physical
Hua Wang, Zhaohui Zhou, Run Long, Oleg Prezhdo
Summary: Compared to the bare Fe2O3 (0001) surface, an alpha-Ga2O3 overlayer reduces surface states and suppresses charge recombination, resulting in a cathodic shift in the onset potential for water oxidation.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Ran Shi, Meng Guo, Run Long
Summary: Simulations show that mixing tin and lead in CH3NH3PbI3 can passivate the midgap state created by an interstitial iodine, reduce electron-hole wave functions overlap, and shorten pure-dephasing time. The charge carrier lifetime extends to 3.6 ns due to reduced nonradiative electron-hole recombination, which is longer than other materials. Tin-lead alloying also increases the defect formation energy, effectively enhancing defect tolerance. Overall, this study reveals the factors controlling the enhanced performance of tin-lead mixed perovskite solar cells.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Cheng Cheng, Oleg V. Prezhdo, Run Long, Wei-Hai Fang
Summary: Identifying photolysis and photothermolysis during a photochemical reaction is challenging due to the non-equilibrium and ultrafast nature of the processes. In this study, the authors use advanced ab initio molecular dynamics to investigate the photodissociation of N2O on a TiO2 surface. They establish the detailed mechanism and find that photothermolysis governs the dissociation when N2O- is short-lived, while photolysis becomes dominant as the N2O- resonance lifetime increases. The authors also demonstrate that thermal dissociation of N2O can be achieved by choosing appropriate metal dopants. Overall, this study provides a fundamental understanding of the competition and synergy between photocatalytic and photothermocatalytic dissociation of N2O and has implications for designing high-performance transition-metal oxide catalysts.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Chenhui Ma, Konghua Yang, Shibo Zhao, Yu Xie, Chunbao Liu, Nan Chen, Chunzhong Wang, Deping Wang, Dong Zhang, Ze Xiang Shen, Fei Du
Summary: We propose an I2-assisted processing method to fabricate the ZnO interface layer on the Zn anode (IAZO), which effectively suppresses Zn dendrite and side reactions. This method has the advantages of sustainability with a high recovery ratio of 67.25% for the raw material I2, and rapid processing time of only 5 minutes. The IAZO anode shows exceptional cycle life (over 3100 hours) and high depth of discharge (52%), outperforming the original Zn anode (less than 220 hours and 1.7%).
ACS ENERGY LETTERS
(2023)
Review
Chemistry, Multidisciplinary
Ahmed Elbanna, Hao Jiang, Qundong Fu, Juan-Feng Zhu, Yuanda Liu, Meng Zhao, Dongjue Liu, Samuel Lai, Xian Wei Chua, Jisheng Pan, Ze Xiang Shen, Lin Wu, Zheng Liu, Cheng-Wei Qiu, Jinghua Teng
Summary: In recent years, two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides, black phosphorus, MXenes, and semimetals, have received extensive attention due to their intriguing properties, underlying physics, and potential for applications. The diverse traits and possibilities offered by 2D materials and their heterostructures provide great opportunities for photonics and plasmonic devices.
Article
Chemistry, Multidisciplinary
Man Zhang, Xiaoxu Liu, Jiangdong Gu, Hui Wang, Hui Liu, Zexiang Shen
Summary: In this study, a self-fractal structure electrode was designed to overcome the challenges of low efficiency and volume expansion when using metal compounds as anodes in sodium-ion batteries. The electrode showed excellent electrochemical performance and stability.
CHINESE CHEMICAL LETTERS
(2023)
Article
Chemistry, Physical
Run Long, Ran Shi
Summary: Defects such as metal vacancies deteriorate the photoelectric properties of metal halide perovskites. Alkali metal dopants have been shown to improve the performance of mixed tin-lead perovskites. Tin vacancies produce iodine trimers and cause rapid electron-hole recombination, but alkali metal additives eliminate trap states and decelerate charge recombination, enhancing the defect tolerance of tin-lead mixed perovskites.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Lin Zhang, Hengwei Qiu, Ran Shi, Jinsong Liu, Guangliu Ran, Wenkai Zhang, Genban Sun, Run Long, Weihai Fang
Summary: This work reports the attractive performance of perovskite photoconductors based on epitaxial CsPbBr3-Pb4S3Br2 Janus nanocrystals, as well as the carrier relaxation and transfer mechanism of the heterojunction. By combining transient optical absorption and quantum dynamics simulation, it is demonstrated that the photogenerated holes on CsPbBr3 can be successfully extracted by Pb4S3Br2, with hole transfer proceeding about three times faster than energy loss and remaining hot for about 300 fs. This feature favors long-range charge separation and transport, resulting in exceptional responsivity (34.0 A W-1) and specific detectivity (1.26 x 1014 Jones) of the Janus nanocrystal photoconductors.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Haoran Lu, Run Long
Summary: The giant spin-orbit coupling (SOC) of lead significantly prolongs the charge carrier lifetimes of lead halide perovskites (LHPs). It is revealed that SOC reduces the non-radiative electron-hole recombination by decreasing the non-adiabatic coupling primarily through reshaping the electron and hole wave functions. Additionally, SOC causes spin mismatch and further decreases the non-adiabatic coupling. The presence of SOC extends the charge carrier lifetime in LHPs by approximately three times compared to the absence of SOC. This study provides fundamental understanding of how SOC minimizes non-radiative charge and energy losses in LHPs.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Hongliang Li, Meng Guo, Zhaohui Zhou, Run Long, Wei-Hai Fang
Summary: Experiments have shown that the lifetime of photoexcited carriers in alpha-Fe2O3 is significantly dependent on the excitation wavelength, but the underlying physical mechanism remains unresolved. In this study, we used nonadiabatic molecular dynamics simulation based on a well-described electronic structure of Fe2O3 to rationalize the puzzling excitation-wavelength dependence of the carrier dynamics. We found that electrons with lower-energy excitation relax fast in the conduction band, while those with higher-energy excitation undergo a slower interband relaxation before a faster intraband relaxation. This study provides insights into the excitation-wavelength dependence of carrier lifetime in Fe2O3, and offers a reference for regulating carrier dynamics in transition-metal oxides through light excitation wavelength.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Ran Shi, Run Long, Wei-Hai Fang, Oleg V. Prezhdo
Summary: By doping complementary cations into 2D layered metal halide perovskites, spontaneous charge separation can be accelerated and charge recombination can be slowed down, resulting in improved photovoltaic performance. Using ab initio nonadiabatic molecular dynamics combined with time-dependent density functional theory, it was found that cesium doping broadens the bandgap and breaks structural symmetry, leading to accelerated charge separation and increased charge carrier lifetime. These findings provide guidelines for future material discovery and perovskite solar cell design.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Hengwei Qiu, Fu Li, Shan He, Ran Shi, Yaoyao Han, Hannikezi Abudukeremu, Lin Zhang, Yan Zhang, Song Wang, Wangyu Liu, Chao Ma, Honghua Fang, Run Long, Kaifeng Wu, Hao Zhang, Jinghong Li
Summary: This study reports the synthesis of uniform, epitaxially grown CsPbBr3/CdS Janus nanocrystal heterostructures with ultrafast charge separation across the electronically coupled interface. Each Janus nanocrystal contains a CdS domain that grows exclusively on a single {220} facet of CsPbBr3 nanocrystals. The promoted charge separation and extraction in epitaxial Janus nanocrystals leads to photoconductors with drastically improved responsivity and detectivity, which is promising for ultrasensitive photodetection.
Article
Nanoscience & Nanotechnology
Nikolaos Aspiotis, Katrina Morgan, Benjamin Maerz, Knut Mueller-Caspary, Martin Ebert, Ed Weatherby, Mark E. Light, Chung-Che Huang, Daniel W. Hewak, Sayani Majumdar, Ioannis Zeimpekis
Summary: This work demonstrates a scalable process for producing large area atomically thin 2D semiconductors with uniform performance. The new atomic layer deposition (ALD) and conversion technique allows for independent control of layer thickness, stoichiometry, and crystallinity. Field effect transistors (FETs) fabricated using this process exhibit high field effect mobility, low subthreshold slope, and high on/off ratios. Additionally, non-volatile memory transistors using ferroelectric FETs (FeFETs) with multiple state switching and a wide memory window are demonstrated, showing the applicability of the process to flexible neuromorphic applications.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Yong Lei, Run Long, Hong Li, Chenling Xiong, Chao Yang, Chenghuai Wu, Zhenxuan Yang, Fuling Tang, Wei Wang
Summary: This study demonstrated a through-wall linear-motor type flux pump for non-contact excitation of high-temperature superconducting magnets. The heating parts of the pump are located outside the cryostat to minimize heat load, and the generated heat is dissipated in the air. By using a cryogenic cooler and an insulation HTS double pancake coil, the injection of direct currents into the closed-loop without current leads was successfully achieved, verifying the feasibility and reliability of the linear-motor type flux pump for HTS magnet excitation.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)