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446 results on '"Ren, Zhiwei"'

1. Thiol‐Functionalized Conjugated Metal–Organic Frameworks for Stable and Efficient Perovskite Photovoltaics

Author

Liang, Xiao, Singh, Mriganka, Wang, Fei, Fong, Patrick WK, Ren, Zhiwei, Zhou, Xianfang, Wan, Xuejuan, Sutter‐Fella, Carolin M, Shi, Yumeng, Lin, Haoran, Zhu, Quanyao, Li, Gang, and Hu, Hanlin

Subjects
Macromolecular and Materials Chemistry, Chemical Sciences, Physical Chemistry, Engineering, Materials Engineering, MOF/perovskite structure, in situ GIWAXS, perovskite solar cells, thiol-functionalized MOF
Abstract

Metal-organic frameworks (MOFs) have been investigated recently in perovskite photovoltaics owing to their potential to boost optoelectronic performance and device stability. However, the impact of variations in the MOF side chain on perovskite characteristics and the mechanism of MOF/perovskite film formation remains unclear. In this study, three nanoscale thiol-functionalized UiO-66-type Zr-based MOFs (UiO-66-(SH)2 , UiO-66-MSA, and UiO-66-DMSA) are systematically employed and examined in perovskite solar cells (PSCs). Among these MOFs, UiO-66-(SH)2 , with its rigid organic ligands, exhibited a strong interaction with perovskite materials with more efficient suppression of perovskite vacancy defects. More importantly, A detailed and in-depth discussion is provided on the formation mechanism of UiO-66-(SH)2 -assisted perovskite film upon in situ GIWAXS performed during the annealing process. The incorporation of UiO-66-(SH)2 additives substantially facilitates the conversion of PbI2 into the perovskite phase, prolongs the duration of stage I, and induces a delayed phase transformation pathway. Consequently, the UiO-66-(SH)2 -assisted device demonstrates reduced defect density and superior optoelectronic properties with optimized power conversion efficiency of 24.09% and enhanced long-term stability under ambient environment and continuous light illumination conditions. This study acts as a helpful design guide for desired MOF/perovskite structures, enabling further advancements in MOF/perovskite optoelectronic devices.

Published
2024

17. A Preliminary Study on the Morphological Changes of an NiTi‐Shaped Memory Alloy Stent in the Vertebral Body

Author

Li Qiaoling, Ren Zhiwei, Zhang Bobo, and Yang Yimin

Subjects
Memory Alloy Stent, Osteoporotic Vertebral Compression Fractures (OVCF), Percutaneous Kyphoplasty (PKP), Orthopedic surgery, RD701-811
Abstract

Objective At present, the most commonly used filler polymethyl methacrylate (PMMA) has the disadvantages of monomer toxicity, heat and leakage, and cannot be applied in young people. Therefore, finding a minimally invasive and good tissue‐compatible alternative material has been a research hotspot in spine surgery in recent years. The aim of this study is to explore whether the memory alloy stent can avoid the complications of bone cement or not. Methods Four non‐adjacent vertebral bodies of the thoracic and lumbar spine in the 18 10‐month‐old pigs were selected as the surgical site and were randomly divided into the scaffold group and the bone cement group. The memory alloy scaffold and PMMA (polymethyl methacrylate) bone cement were placed via percutaneous puncture, and intraoperative fluoroscopy and micro‐CT were used to observe the changes in the height of scaffolds and bone cement in the vertebral body immediately, 6 weeks, and 12 weeks after operation, the microstructural parameters of the bone trabeculae (bone volume fraction, bone surface volume ratio, bone trabeculae number) were also measured. Results The memory alloy stent could expand in the vertebral body, and its height gradually increased with time; additionally, the height of the bone cement mass did not change with time (p = 0.00). New bone trabeculae could grow into the scaffold along the gap, and the volume fraction of bone, the volume ratio of bone surface area, and the number of bone trabeculae increased gradually (p = 0.00). However, the volume fraction of bone, the volume ratio of bone surface area, and the number of trabeculae in the cement block decreased gradually (p = 0.00). Conclusions Memory alloy scaffolds have dynamic expansion characteristics in vivo, which can effectively avoid the complications of bone cement. Thus, it is beneficial to explore this minimally invasive treatment for vertebral compression fractures.

Published
2023
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23. Perovskite Quantum Wells Formation Mechanism for Stable Efficient Perovskite Photovoltaics—A Real‐Time Phase‐Transition Study

Author

Hu, Hanlin, Qin, Minchao, Fong, Patrick WK, Ren, Zhiwei, Wan, Xuejuan, Singh, Mriganka, Su, Chun‐Jen, Jeng, U‐Ser, Li, Liang, Zhu, Jiajie, Yuan, Mingjian, Lu, Xinhui, Chu, Chih‐Wei, and Li, Gang

Subjects
perovskite photovoltaics, perovskite quantum wells, phase&#8208, transitions, phase-transitions, Physical Sciences, Chemical Sciences, Engineering, Nanoscience & Nanotechnology
Abstract

The combination of a bulk 3D perovskite layer and a reduced dimensional perovskite layer (perovskite quantum wells (PQWs)) is demonstrated to enhance the performance of perovskite solar cells (PSCs) significantly in terms of stability and efficiency. This perovskite hierarchy has attracted intensive research interest; however, the in-depth formation mechanism of perovskite quantum wells on top of a 3D perovskite layer is not clearly understood and is therefore the focus of this study. Along with ex situ morphology and photophysical characterization, the time-resolved grazing-incidence wide-angle X-ray scattering (TS-GIWAXS) technique performed in this study provides real-time insights on the phase-transition during the organic cation (HTAB ligand molecule) coating and PQWs/3D architecture formation process. A strikingly strong ionic reaction between the 3D perovskite and the long-chain organic cation leads to the quick formation of an ordered intermediate phase within only a few seconds. The optimal PQWs/3D architecture is achieved by controlling the HTAB casting, which is assisted by time-of-flight SIMS characterization. By controlling the second ionic reaction during the long-chain cation coating process, along with the fluorinated poly(triarylamine) (PTAA) as a hole-transport layer, the perovskite solar cells demonstrate efficiencies exceeding 22% along with drastically improved device stability.

Published
2021

26. MuFA (Multi-type Fourier Analyzer): A tool for batch generation of MuMax3 input scripts and multi-type Fourier analysis from micromagnetic simulation output data

Author

Ren, Zhiwei, Jin, Lichuan, Wen, Tianlong, Liao, Yulong, Tang, Xiaoli, Zhang, Huaiwu, and Zhong, Zhiyong

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

We present a tool for batch generation of input scripts and multi-type Fourier analysis from simulation results for the micromagnetic software MuMax3. The introduction of graphical user interface and parameter-sweeping functionality strongly speed up the input scripts creation and accelerate model optimization processes consequently. Three types of important Fourier analysis methods are provided for the acquisition of the quantitative frequency compositions, the spin-wave dispersion curve and the spatial distribution of spin-wave powers at different frequencies, respectively. Since the Fourier analysis is accelerated by parallel computations, the time cost is reduced to an acceptable level even in the presentation of tens of gigabytes data. With the MuMax3 and our proposal, a complete micromagnetic simulating tool chain from scripts generation to post analysis has been developed.

Published
2019
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34. Self-assembly enables simple structure organic photovoltaics via green-solvent and open-air-printing: Closing the lab-to-fab gap

Author

Tang, Hua, Lv, Jie, Liu, Kuan, Ren, Zhiwei, Chandran, Hrisheekesh Thachoth, Huang, Jiaming, Zhang, Ying, Xia, Hao, Khan, Jafar I., Hu, Dingqin, Yan, Cenqi, Oh, Jiyeon, Chen, Shanshan, Chu, Shenglong, Fong, Patrick W.K., Chen, Haiyan, Xiao, Zhengguo, Yang, Changduk, Kan, Zhipeng, Laquai, Frédéric, Lu, Shirong, and Li, Gang

Published
2022
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50. Effect of lattice type on biomechanical and osseointegration properties of 3D-printed porous Ti6Al4V scaffolds

Author

Liu, Jiantao, primary, Wang, Kao, additional, Wang, Runqing, additional, Yin, Zhanhai, additional, Zhou, Xiaoling, additional, Xu, Aofei, additional, Zhang, Xiwei, additional, Li, Yiming, additional, Wang, Ruiyan, additional, Zhang, Shuyuan, additional, Cheng, Jun, additional, Bian, Weiguo, additional, Li, Jia, additional, Ren, Zhiwei, additional, Sun, Mengyuan, additional, Yang, Yin, additional, Wang, Dezhi, additional, and Ren, Jing, additional

Published
2024
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