Article
Chemistry, Physical
Wei Li, Alexey V. Akimov
Summary: For simulations using the repetition approximation, the state transition time scales may strongly depend on the length of the repeated data, and the repetition approach could under-or overestimate the time scales by a factor of <= 7-8. This dependence is not directly related to the dispersion of energy gap and nonadiabatic coupling frequencies, but may be influenced by the magnitude of the nonadiabatic couplings.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Ritabrata Sarkar, Md Habib, Sougata Pal
Summary: This study investigates the charge recombination mechanism in macromolecular porphyrin nanorings and finds that the mode of the linker in the nanoring strongly affects charge recombination. The all-butadiyne-linkage inhibits carrier relaxation while the partially fused nanoring expedites quantum transitions. The larger optical gap in the all-butadiyne-linkage nanoring reduces nonadiabatic coupling, resulting in a longer carrier lifetime. Intense phonon peaks and rapid coherence loss also contribute to the prolonged carrier lifetime.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Michele Pizzochero, Efthimios Kaxiras
Summary: The addition of hydrogen atom to zigzag graphene nanoribbons (ZGNRs) is investigated, revealing the role of pi-magnetism in governing the chemistry of ZGNRs and the influence of chemisorbed hydrogen atom on the pi-magnetism. The peculiar interplay between chemistry and magnetism is established at the zigzag edges of graphene.
Article
Materials Science, Multidisciplinary
Yuxiang Gu, Lin Shi, Jun-Wei Luo, Shu-Shen Li, Lin-Wang Wang
Summary: SiC is an important wide-bandgap semiconductor with the Z(1/2) center being identified as a carrier lifetime killer. The Z(1/2) center originates from carbon vacancies (V-C), and through first-principles calculations, it has been confirmed that the V-C is indeed the Z(1/2) center with multiphonon-assisted nonradiative recombination rates.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Chemistry, Physical
Mohammad Shakiba, Alexey V. Akimov
Summary: Through NA-MD calculations in a C3N4 monolayer, the dependence of electron-hole recombination time scales on the size of the simulation supercell and charge carrier concentration is demonstrated. By using extended tight-binding electronic structure calculations, calculations in C3N4 monolayers with up to 5600 atoms have been conducted. The predicted time scales vary from 7 ps to 23 ns depending on system size and NA-MD methodology.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Nanoscience & Nanotechnology
Lisha Xie, Junni Xie, Shurong Wang, Bin Chen, Chenguang Yang, Zhen Wang, Xiaobo Liu, Jiangzhao Chen, Kun Jia, Feng Hao
Summary: By passivating defects in perovskite solar cells and effectively inhibiting nonradiative recombination, the synthesized fluorinated oligomer FO-19 achieves a high power conversion efficiency of 21.23% for MAPbI(3)-based PSCs, while also improving humidity and thermal stability. This work provides insights into achieving high-efficiency and stable PSCs through fluorinated additive engineering.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Energy & Fuels
Xuping Liu, Jihuai Wu, Tingting Zhang, Deng Wang, Xiao Jin, Bing Xu, Zhen Huang, Dongyu Li, Qinghua Li
Summary: By doping organic molecules and surface modification, both anion and cation defects in the perovskite layer can be simultaneously mitigated, thus enhancing the performance and stability of perovskite solar cells.
Article
Chemistry, Physical
Yunyan Fan, Yumei Lin, Kelvin H. L. Zhang, Ye Yang
Summary: The nonradiative recombination mechanism in hematite single crystals under solar illumination was investigated, highlighting the role of a pseudocoordination-complex (PCC) model and the temperature-dependent quantum tunneling probability of nuclear configuration in determining the rate of nonradiative recombination at room temperature.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Physics, Applied
Axel R. R. Persson, Anders Gustafsson, Zhaoxia Bi, Lars Samuelson, Vanya Darakchieva, Per O. A. Persson
Summary: In this study, we investigated the optical properties of InGaN platelets with a quantum well structure for nano-LEDs emitting red light and their correlation with the atomic structure. Using cathodoluminescence measurements and a spectroscopy-thinning-imaging method, we observed how stacking mismatch boundaries intersect with the quantum well in plan-view and result in diminished cathodoluminescence intensity. The findings emphasize the significance of avoiding stacking mismatch in small LED structures due to the presence of relatively large non-radiative recombination regions caused by the mismatch boundaries.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Rita Maji, Eleonora Luppi, Elena Degoli
Summary: The interfacial structure of a silicon grain boundary (Si-GB) has a significant impact on its chemical functionalization and various physical-chemical properties of the material. This study provides an atomistic understanding of the role of the GB interface and its importance in high performance technological applications. The influence of different sigma 3{1121 Si-GB models on the structural reconstruction and properties of the GB interface has been investigated, along with the impact of vacancies and light impurities. The behavior of (1 x 1) and (1 x 2) models is significantly different under the influence of vacancies and the segregation of impurities.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Sheng Jiang, Shaobing Xiong, Wei Dong, Danqin Li, Yuting Yan, Menghui Jia, Yannan Dai, Qingbiao Zhao, Kai Jiang, Xianjie Liu, Liming Ding, Mats Fahlman, Zhenrong Sun, Qinye Bao
Summary: In this study, solution-processed chromium multioxide was used as the charge transport layer in perovskite solar cells, resulting in increased efficiency and stability by reducing defects and adjusting the energy band gap.
Article
Chemistry, Physical
Sheng Jiang, Shaobing Xiong, Hongbo Wu, Dongyang Zhao, Xiaomeng You, Yehui Xu, Menghui Jia, Wei Bai, Zaifei Ma, Xianjie Liu, Yefeng Yao, Zhenrong Sun, Qinye Bao
Summary: A surface treatment strategy is developed by heat-induced decomposition of a thin interlayer 2,7-Naphthaleneditriflate (NAP) to in situ reconstruct perovskite energetics. This strategy enhances charge extraction and suppresses charge recombination, resulting in a significantly improved power conversion efficiency of perovskite solar cells (PSCs). The reconstructed surface also improves the crystallinity and stability of the perovskite film, making it a promising approach for the design of high-efficiency and stable PSCs.
ADVANCED ENERGY MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Manju Kumari Jaiswal, Biswajit Choudhury
Summary: This study reports the hydrothermal fabrication of hydrated hexagonal/orthorhombic mixed-phase WO3 core.shell nanoribbons for the photodegradation of methylene blue. The mixed-phase core.shell exhibits 2.3 times higher photocatalytic activity than monoclinic and hexagonal crystalline phases. Intercalated water, trap states, and prolonged carrier lifetimes play significant roles in enhancing the photocatalytic performance of the hydrated mixed phase.
ACS APPLIED NANO MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Antoine Jay, Olivier Hardouin Duparc, Jelena Sjakste, Nathalie Vast
Summary: The Raman spectrum of boron carbide under pressure is explained by the vibrations of (B11C) icosahedra and C-B-C chains, while the behavior of a broad Raman band at low frequency is attributed to the activation of the chain bending mode in flexured chains. The 270 cm-1 ambient-P mode is proposed as a fingerprint for identifying chain defects and deviations from rhombohedral symmetry in boron carbide.
Article
Materials Science, Multidisciplinary
A. Csore, N. T. Son, A. Gali
Summary: The study identifies the potentially quantum technology applicable V-Si(-) defect and related centers in silicon carbide, yet the exact sources of some signals remain unclear, prompting the proposal of V-1-related pair defect models. By density functional theory calculations, the electronic structures and magneto-optical properties of these centers are determined, and their optical signals are predicted for future experimental identification.
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, 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
Edoardo Mosconi, Asma A. Alothman, Run Long, Waldemar Kaiser, Filippo De Angelis
Summary: Controlling the chemical properties of A-site cations in 2D metal halide perovskites (MHPs) and in 2D/3D assemblies is crucial for stable and efficient optoelectronic devices. This study rationalizes the chemical interactions of different classes of organic cations in 2D MHPs, emphasizing the potential enhancement in stability through hydrogen bonding within the organic framework. This observation may lead to the design of organic cations with stronger intermolecular interactions for increased stability in MHP-based devices.
ACS ENERGY 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
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)
Article
Chemistry, Physical
Ran Shi, Run Long
Summary: Defects like metal vacancies degrade the photoelectric properties of metal halide perovskites by serving as nonradiative recombination centers. Nonadiabatic molecular dynamics revealed that alkali metal dopants significantly enhance the performance of mixed tin-lead perovskites. Alkali dopants raise the formation energy of tin vacancies to 1 eV, resulting in decreased defect concentration. Tin vacancies facilitate the doping of alkali metals into perovskites. These vacancies generate iodine trimers that create midgap states and promote rapid electron-hole recombination. Alkali metal additives eliminate trap states, weaken nonadiabatic coupling, and slow down charge recombination with a coefficient of 5.5 compared to defective tin-lead mixed perovskites. Our research provides a theoretical model for alkali metal passivation at the atomic level, enhancing the defect tolerance of tin-lead mixed perovskites and offering valuable insights for optimizing high-performance 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 presents the attractive device performance of perovskite photoconductors based on epitaxial CsPbBr3-Pb4S3Br2 Janus nanocrystals. The carrier relaxation and transfer mechanism of the heterojunction is also investigated. The study demonstrates that the photogenerated holes on CsPbBr3 can be efficiently extracted by Pb4S3Br2, leading to long-range charge separation and transport, resulting in exceptional responsivity and specific detectivity.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Hua Wang, Zhaohui Zhou, Run Long, Oleg Prezhdo
Summary: In this study, ab initio quantum dynamics simulations were performed to investigate the effect α-Ga2O3 overlayers on charge recombination in Hematite photoanode. The results showed that the overlayers eliminated surface states and suppressed charge recombination, explaining the observed cathodic shift in the onset potential for water oxidation and increasing charge carrier lifetime. This work advances the understanding of the influence of surface passivation on charge recombination dynamics and provides guidance for designing novel α-Fe2O3 photoanodes.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Ran Shi, Meng Guo, Run Long
Summary: Simulations show that mixing tin with lead in CH3NH3PbI3 can passivate the midgap state created by an interstitial iodine through compressive strain and upshifted valence band maximum, reduce electron-hole wave functions overlap, and shorten pure dephasing time through high-frequency phonon modes. The significantly reduced nonradiative recombination leads to an extended charge carrier lifetime of 3.6 ns, which is an order of magnitude longer than the Ii-containing CH3NH3PbI3, over 2.5 times longer than pristine CH3NH3PbI3, and even 1.7 times longer than tin-lead mixed perovskite without I-i defects. Tin-lead alloying also increases the I-i defect formation energy, effectively enhancing defect tolerance. This study reveals the factors controlling the enhanced performance of tin-lead mixed perovskite solar cells.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)