Wenna Du

National Center for Nanoscience and Technology

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i-10 index

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Xinfeng Liu

National Center for Nanoscience and Technology

Qing Zhang

Peking University

Yang Mi

Linyi University

Qiuyu Shang

Peking University

Xianxin Wu

National Center for Nanoscience and Technology

Yangguang Zhong

Hunan University

Xinyu Sui

Peking University

Jie Chen

Chinese Academy of Sciences

Jianwei Shi

Tongji University

Liyun Zhao

Chinese Academy of Sciences

Cooperative Institutions

Chinese Academy of Sciences

148

University of Chinese Academy of Sciences

129

National Center for Nanoscience and Technology

Peking University

Beijing National Laboratory for Molecular Sciences

Center for NanoScience

Nanyang Technological University

Tsinghua University

University of Science and Technology of China

Central South University

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Polaritons and polariton condensates in perovskites

SPIE eBooks (2023)

Zhuoya Zhu Shuai Zhang Wenna Du Xinfeng Liu Zhuoya Zhu

Polariton is the bosonic quasiparticle in the cavity, which provides a new experimental way to achieve Bose-Einstein condensation (BEC) at higher temperatures compared with atomic or excitonic BEC. Meanwhile, the polariton has considerable tolerance for defects in the crystal owing to the spatial phase-coherent wavefunction extension through its photonic component. Conventional inorganic semiconductor materials for realizing polaritons, such as CdTe, GaAs, etc., require lower temperatures to obtain strong excitonic nonlinearity because of the small exciton binding energy, and the Frenkel excitons in the organic semiconductors possess weak Coulomb interactions, which may hinder the polariton-polariton interactions and the relaxation to the ground state. The metal halide perovskites inherit the advantages of both, including large exciton binding energy and oscillator strength, which have become the ideal platform to study the polariton BEC at room temperature. We start with the concept and properties of polariton and gradually reveal its bond with perovskites.

Oscillator strength

Exciton-polaritons

10.1117/3.100002.ch14

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Citations (0)

Flexible construction of heteroatom-free g-C3N4/g-C3N4 homojunction with switching charge dynamics toward efficient photo-piezocatalytic performance

Applied Catalysis B Environment and Energy (2024)

Huanhuan Zhai Hongqin Liu Yi Zhang Jiaxin Tong Xinfeng Liu

Homojunction

Heteroatom

Graphitic carbon nitride

10.1016/j.apcatb.2024.123909

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Citations (15)

Strong Exciton–Photon Coupling and Lasing Behavior in All-Inorganic CsPbBr₃ Micro/Nanowire Fabry-Pérot Cavity

ACS Photonics (2018)

Wenna Du Shuai Zhang Jia Shi Jie Chen Zhi‐Yong Wu

All-inorganic perovskite micro/nanowire materials hold great promises as nanoscale coherent light source due to their superior optical and electronic properties. The coupling strength between exciton and photon in this system is important for their optical application, however, is rarely studied. In this work, we demonstrated the strong coupling of exciton-photon and polariton lasing in high quality CsPbBr3 micro/nanowires synthesized by a CVD method. By exploring spatial resolved PL spectra of CsPbBr3 cavity, we observed mode volume dependent coupling strength with a vacuum Rabi splitting up to 656 meV, as well as significant increase in group index. Moreover, low threshold polariton lasing was achieved at room temperature within strong coupling regime; the polariton characteristic is confirmed by comparing lasing spectra with waveguided output spectra and the dramatically reduced lasing threshold. Our present results provide new avenues to achieve high coupling strengths potentially enabling application of exciting phenomena such as Bose–Einstein condensation of polaritons, efficient light-emitting diodes, and lasers.

Optical cavity

10.1021/acsphotonics.7b01593

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Citations (165)

All‐Inorganic CsPbBr₃ Nanowire Based Plasmonic Lasers

Advanced Optical Materials (2018)

Zhi‐Yong Wu Jie Chen Yang Mi Xinyu Sui Shuai Zhang

Abstract Plasmonic nanolaser holds great potential in breaking down the diffraction limit of conventional optics to the deep sub‐wavelength regime and in ultrafast lasing dynamics. However, plasmonic laser devices are constrained in practical applications due to their high cost and high thresholds. All‐inorganic cesium lead halide perovskites are promising solutions for their excellent optical gain properties and high emission efficiency. In this work, high‐quality single‐crystalline CsPbBr 3 perovskite nanowires (NWs) are synthesized by chemical vapor deposition method. The plasmonic lasing is achieved from the CsPbBr 3 nanowire based plasmonic devices with lasing threshold down to ≈6.5 µJ cm −2 at room temperature. The highly polarized emission parallel to nanowire axis and polarization‐sensitive pump response confirm the plasmonic characteristic in these devices. Furthermore, time‐resolved photoluminescence study suggests that the radiative recombination lifetime of CsPbBr 3 NW is shortened by a factor of ≈6.14 due to Purcell effect. The lasing threshold of plasmonic device increases along with the nanowire length, indicating greater potential in small size and integration in plasmonic device than its photonic counterparts. The results not only provide a solution to fabricate low‐cost nanowire based plasmonic lasers, but also advocate the prospect of all‐inorganic perovskite nanowires as promising candidates in plasmonic‐based devices.

Nanolaser

10.1002/adom.201800674

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Citations (130)

Cocrystals Strategy towards Materials for Near‐Infrared Photothermal Conversion and Imaging

Angewandte Chemie (2018)

Yu Wang Weigang Zhu Wenna Du Xinfeng Liu Xiaotao Zhang

Abstract A cocrystal strategy with a simple preparation process is developed to prepare novel materials for near‐infrared photothermal (PT) conversion and imaging. DBTTF and TCNB are selected as electron donor (D) and electron acceptor (A) to self‐assemble into new cocrystals through non‐covalent interactions. The strong D–A interaction leads to a narrow band gap with NIR absorption and that both the ground state and lowest‐lying excited state are charge transfer states. Under the NIR laser illumination, the temperature of the cocrystal sharply increases in a short time with high PT conversion efficiency ( η =18.8 %), which is due to the active non‐radiative pathways and inhibition of radiative transition process, as revealed by femtosecond transient absorption spectroscopy. This is the first PT conversion cocrystal, which not only provides insights for the development of novel PT materials, but also paves the way of designing functional materials with appealing applications.

Cocrystal

10.1002/ange.201712949

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Citations (62)

Interfacial Molecular Doping at Donor and Acceptor Interface in Bilayer Organic Solar Cells

Solar RRL (2022)

Hong Zhang Xuning Zhang Yanxun Li Gaosheng Huang Wenna Du

Molecular doping is an effective means to tune the optoelectronic properties of organic semiconductors. Despite its versatility, its application in bulk heterojunction (BHJ) organic solar cells (OSCs) is still limited, especially blend‐cast doping. Difficulties in desolving molecular dopants in weakly polar solvents have led to the formation of undesired structures, with relatively high concentrations of dopants affecting the bicontinuous BHJ morphology. Bilayer OSCs are stacked structures with sequential deposition of donor and acceptor films, which make important contributions to the fine tuning of morphology and balanced charge transport. The sequential deposition of thin films in bilayer devices organically facilitates the sequential doping of pure donor polymers by dopants. The sequential doping of the dopant at the interface between the donor and the acceptor can efficiently improve the carrier mobility and the charge transfer between the donor and the acceptor without damaging the quality of the film, thus improving the device performance efficiently. With three different dopants F4TCNQ, F6TCNNQ, and BCF, sequential interfacial doping in bilayer devices is found to be a versatile and effective method to improve device performance. Making this simple doping strategy promising for high‐performance bilayer OSCs, it is evaluated as a promising alternative to BHJ OSCs.

Acceptor

Organic semiconductor

10.1002/solr.202101096

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Citations (4)

InAs/GaSb core–shell nanowires grown on Si substrates by metal–organic chemical vapor deposition

Nanotechnology (2016)

Xianghai Ji Xiaoguang Yang Wenna Du Huayong Pan Shuai Luo

We report the growth of InAs/GaSb core-shell heterostructure nanowires with smooth sidewalls on Si substrates using metal-organic chemical vapor deposition with no assistance from foreign catalysts. Sb adatoms were observed to strongly influence the morphology of the GaSb shell. In particular, Ga droplets form on the nanowire tips when a relatively low TMSb flow rate is used, whereas the droplets are missing and the radial growth of the GaSb is enhanced due to a reduction in the diffusion length of the Ga adatoms when the TMSb flow rate is increased. Moreover, transmission electron microscopy measurements revealed that the GaSb shell coherently grew on the InAs core. The results obtained here show that the InAs/GaSb core-shell nanowires grown using the Si platform have strong potential in the fabrication of future nanometer-scale devices and in the study of fundamental quantum physics.

Nanometre

Deposition

10.1088/0957-4484/27/27/275601

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Citations (18)

Photophysics and its application in photon upconversion

Nanoscale (2024)

Yutong Zhang Wenna Du Xinfeng Liu

Photoluminescence (PL) upconversion is a phenomenon involving light-matter interaction, where the energy of the emitted photons is higher than that of the incident photons. PL upconversion has promising applications in optoelectronic devices, displays, photovoltaics, imaging, diagnosis and treatment. In this review, we summarize the mechanism of PL upconversion and ultrafast PL physical processes. In particular, we highlight the advances in laser cooling, biological imaging, volumetric displays and photonics.

Photon Upconversion

Two-photon excitation microscopy

10.1039/d3nr05450k

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Citations (3)

Fabry–Pérot Oscillation and Room Temperature Lasing in Perovskite Cube‐Corner Pyramid Cavities

Small (2018)

Yang Mi Zhixiong Liu Qiuyu Shang Xinxiang Niu Jia Shi

Recently, organometal halide perovskite-based optoelectronics, particularly lasers, have attracted intensive attentions because of its outstanding spectral coherence, low threshold, and wideband tunability. In this work, high-quality CH3 NH3 PbBr3 single crystals with a unique shape of cube-corner pyramids are synthesized on mica substrates using chemical vapor deposition method. These micropyramids naturally form cube-corner cavities, which are eminent candidates for small-sized resonators and retroreflectors. The as-grown perovskites show strong emission ≈530 nm in the vertical direction at room temperature. A special Fabry-Pérot (F-P) mode is employed to interpret the light confinement in the cavity. Lasing from the perovskite pyramids is observed from 80 to 200 K, with threshold ranging from ≈92 µJ cm-2 to 2.2 mJ cm-2 , yielding a characteristic temperature of T0 = 35 K. By coating a thin layer of Ag film, the threshold is reduced from ≈92 to 26 µJ cm-2 , which is accompanied by room temperature lasing with a threshold of ≈75 µJ cm-2 . This work advocates the prospect of shape-engineered perovskite crystals toward developing micro-sized optoelectronic devices and potentially investigating light-matter coupling in quantum optics.

Pyramid (geometry)

Cube (algebra)

Oscillation (cell signaling)

10.1002/smll.201703136

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Citations (74)

Wavelength Tunable Plasmonic Lasers Based on Intrinsic Self-Absorption of Gain Material

ACS Photonics (2017)

Qing Zhang Qiuyu Shang Jia Shi Jie Chen Rui Wang

Multicolor plasmonic nanowire lasers enable below diffraction-limit directional optical waveguiding and amplification vital to the development of next generation compact on-chip optical communications, super-resolution imaging, display technologies, and so on. However, progress in developing these compact lasers for different wavelengths is severely curtailed by the few complex fabrication methods available. In this work, we demonstrate wavelength-tunable plasmonic nanowire lasers by leveraging the intrinsic optical self-absorption of the gain medium. The plasmonic lasing wavelength is tunable from 465 to 491 nm by simply adjusting the nanowire length, that is, by approximately 76% over the interval width of the emission spectrum. The Purcell factor of plasmonic nanowire cavity decreases with increasing nanowire length; while the propagation loss increases from 1020 to 8354 cm–1 with decreasing nanowire diameter, exhibiting a plasmonic-photonic mode transition at diameters around 120–150 nm. Importantly, our findings advance the fundamental understanding and provide a new approach for engineering wavelength tunable plasmonic lasers.

Nanophotonics

10.1021/acsphotonics.7b00757

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Citations (33)