| 1. |
- Gao, Yijun, et al.
(författare)
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Enhancing PbS Colloidal Quantum Dot Tandem Solar Cell Performance by Graded Band Alignment
- 2019
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 10:19, s. 5729-5734
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal quantum dot solids are attractive candidates for tandem solar cells because of their widely tunable bandgaps. However, the development of the quantum dot tandem solar cell has lagged far behind that of its single-junction counterpart. One of the fundamental problems with colloidal quantum dot solar cells is the relatively small diffusion length, which limits the quantum dot absorbing layer thickness and hence the power conversion efficiency. In this research, guided by optical modeling and utilizing a graded band alignment strategy, a two-terminal monolithic solution-processed quantum dot tandem solar cell has been successfully fabricated and a power conversion efficiency of 6.8% has been achieved. The band grading approach utilized the complementary tuning of work functions and band alignment through judicious choices of the nanoparticle surface chemistry and quantum dot confined size. This work demonstrates a general approach to improving the efficiency for tandem thin-film solar cells.
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| 2. |
- Li, Jiahui, et al.
(författare)
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Extra low friction coefficient caused by the formation of a solid-like layer : A new lubrication mechanism found through molecular simulation of the lubrication of MoS2 nanoslits
- 2018
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Ingår i: Chinese Journal of Chemical Engineering. - : Elsevier. - 1004-9541 .- 2210-321X. ; 26:12, s. 2412-2419
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Tidskriftsartikel (refereegranskat)abstract
- Monolayer molybdenum disulfide (MoS2) is a novel two-dimensional material that exhibits potential application in lubrication technology. In this work, molecular dynamics was used to investigate the lubrication behaviour of different polar fluid molecules (i.e., water, methanol and decane) confined in monolayer MoS2 nanoslits. The pore width effect (i.e., 1.2, 1.6 and 2.0 nm) was also evaluated. Results revealed that decane molecules exhibited good lubricating performance compared to the other two kinds of molecules. The friction coefficient followed the order of decane < methanol < water, and decreased evidently as the slit width increased, except for decane. Analysis of the spatial distribution and mobility of different confined fluid molecules showed that a solid-like layer was formed near the slit wall. This phenomenon led to the extra low friction coefficient of confined decane molecules
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| 3. |
- Liu, Baoqing, et al.
(författare)
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Experimental Investigation on Drawdown of Floating Particles in Viscous Systems Driven by Coaxial Mixers
- 2019
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Ingår i: Industrial and Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 58, s. 11060-11071
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Tidskriftsartikel (refereegranskat)abstract
- In view of the current situation of single form and low efficiency, a coaxial mixer with wide adaptability was combined with the drawdown of floating particles in viscous systems, and the effects of operation mode, impeller type, impeller diameter, impeller submergence, system viscosity, solid concentration and particle size were investigated experimentally. It is found that the coaxial mixer under corotation mode can achieve the critical drawdown of floating particles with lower speed and power than the corresponding single-shaft mixer, and the advantage becomes more obvious with increasing system viscosity and solid volume fraction. Under the same conditions, compared with the axial and radial flow impellers, the mixed flow impeller with down-pumping mode can effectively draw the floating particles down with the lowest critical speed and power. Moreover, a larger impeller diameter and smaller impeller submergence are recommended for the drawdown of floating particles, but the impeller diameter should not exceed half of the vessel diameter.
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| 4. |
- Teh, Zhi Li, et al.
(författare)
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Enhanced Power Conversion Efficiency via Hybrid Ligand Exchange Treatment of p-Type PbS Quantum Dots
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:20, s. 22751-22759
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Tidskriftsartikel (refereegranskat)abstract
- PbS quantum dot solar cells (QDSCs) have emerged as a promising low-cost, solution-processable solar energy harvesting device and demonstrated good air stability and potential for large-scale commercial implementation. PbS QDSCs achieved a record certified efficiency of 12% in 2018 by utilizing an n+–n–p device structure. However, the p-type layer has generally suffered from low carrier mobility due to the organic ligand 1,2-ethanedithiol (EDT) that is used to modify the quantum dot (QD) surface. The low carrier mobility of EDT naturally limits the device thickness as the carrier diffusion length is limited by the low mobility. Herein, we improve the properties of the p-type layer through a two-step hybrid organic ligand treatment. By treating the p-type layer with two types of ligands, 3-mercaptopropionic acid (MPA) and EDT, the PbS QD surface was passivated by a combination of the two ligands, resulting in an overall improvement in open-circuit voltage, fill factor, and current density, leading to an improvement in the cell efficiency from 7.0 to 10.4% for the champion device. This achievement was a result of the improved QD passivation and a reduction in the interdot distance, improving charge transport through the p-type PbS quantum dot film.
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| 5. |
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| 6. |
- Wang, Lihui, et al.
(författare)
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Designing function blocks for distributed process planning and adaptive control
- 2009
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Ingår i: Engineering applications of artificial intelligence. - : Elsevier. - 0952-1976 .- 1873-6769. ; 22:7, s. 1127-1138
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this research is to develop methodologies and a framework for distributed process planning and adaptive control using function blocks. Facilitated by real-time monitoring system, the proposed methodologies can be applied to integrate with functions of dynamic scheduling in a distributed environment. A function block-enabled process planning approach is proposed to handle dynamic changes during process plan generation and execution. This paper focuses mainly on distributed process planning, particularly on the development of a function block designer that can encapsulate generic process plans into function blocks for runtime execution. As function blocks can sense environmental changes on a shop floor, it is expected that a so-generated process plan can adapt itself to the shop floor environment with dynamically optimized solutions for plan execution and process monitoring.
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| 7. |
- Zhao, Jun, et al.
(författare)
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Two-dimensional (2D) graphene nanosheets as advanced lubricant additives : A critical review and prospect
- 2021
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Ingår i: Materials Today Communications. - : Elsevier. - 2352-4928. ; 29
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Tidskriftsartikel (refereegranskat)abstract
- Graphene is a two-dimensional nanomaterial with a monolayer of atomic thickness. Due to its high specific surface area, weak interlayer interaction and good chemical stability, graphene has shown remarkable tribological properties as a lubricant additive. This review focuses on the research progress on graphene-based additives witnessed in recent years. Various synthesis methods of graphene nanomaterials have been displayed, and the review especially highlights the preparation processes of graphene using as a lubricant additive. The dispersion stability of graphene in lubricants is a key concern that has been presented. Besides physical and chemical modifications, a new dispersion method of structural regulation, which has obvious self-dispersed effect, is also discussed in detail. Furthermore, the lubrication mechanisms of graphene additives have been summarized, which will be highly beneficial to optimize the synthesis processes and to regulate the microstructures of graphene for achieving better lubrication. Finally, the challenges and outlook of the future studies on graphene additives are presented in the field of lubrication.
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| 8. |
- Zhao, Jun, et al.
(författare)
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Using Green, Economical, Efficient Two-Dimensional (2D) Talc Nanosheets as Lubricant Additives under Harsh Conditions
- 2022
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional (2D) nanomaterials have attracted much attention for lubrication enhancement of grease. It is difficult to disperse nanosheets in viscous grease and the lubrication performances of grease under harsh conditions urgently need to be improved. In this study, the 2D talc nanosheets are modified by a silane coupling agent with the assistance of high-energy ball milling, which can stably disperse in grease. The thickness and size of the talc nanosheet are about 20 nm and 2 µm. The silane coupling agent is successfully grafted on the surface of talc. Using the modified-talc nanosheet, the coefficient of friction and wear depth can be reduced by 40% and 66% under high temperature (150 °C) and high load (3.5 GPa), respectively. The enhancement of the lubrication and anti-wear performance is attributed to the boundary adsorbed tribofilm of talc achieving a repairing effect of the friction interfaces, the repairing effect of talc on the friction interfaces. This work provides green, economical guidance for developing natural lubricant additives and has great potential in sustainable lubrication.
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