Search

Your search keyword '"Zhu, Yuejin"' showing total 799 results
Start Over Author "Zhu, Yuejin"
799 results on '"Zhu, Yuejin"'

34. Synergistic passivation and energy level alignment by graphene quantum dots for high performance inverted CsPbI3 perovskite solar cells.

Author

Xiao, Cong, Liu, Zhongyu, Liu, Jiayin, Xing, Haoming, Wang, Jianwei, Zhang, Jing, Huang, Like, Hu, Ziyang, Zhu, Yuejin, Chen, Da, and Liu, Xiaohui

Subjects
ENERGY levels (Quantum mechanics), ENERGY dissipation, OPEN-circuit voltage, QUANTUM dots, SOLAR cells
Abstract

Inorganic CsPbI3 perovskite solar cells (PSCs) have garnered considerable attention due to their high thermal stability and promising application in tandem devices. However, further advancement of the performance of CsPbI3 PSCs is restricted by severe nonradiative recombination, which is related to substantial defects and mismatched energy levels. Herein, the versatile graphene quantum dots (GQDs) are introduced to modify the CsPbI3 surface to improve interface contact and mitigate energy loss. GQD modification can not only effectively passivate surface defects via coordinating with the undercoordinated Pb2+ but also improve energy level alignment, contributing to efficient charge extraction and suppression of nonradiative recombination. Consequently, GQDs-based inverted CsPbI3 devices deliver a champion power conversion efficiency (PCE) of 18.98% with a high open-circuit voltage (VOC) of 1.141 V and are greatly superior to the control device obtaining a poor PCE of 13.29% with a VOC of 0.986 V. Moreover, GQDs can form a protective layer at the perovskite interface to resist external invasion, significantly boosting the device stability. Our findings establish the promising application of GQD modification as a compelling strategy for achieving high performance inorganic photovoltaic devices. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

35. Implementation and verification of an OpenFOAM solver for gas-droplet two-phase detonation combustion.

Author

Chen, Huangwei, Zhao, MingHao, Qiu, Hua, and Zhu, Yuejin

Subjects
STABLE Diffusion, REACTIVE flow, DYNAMIC balance (Mechanics), SHOCK waves, RIEMANN-Hilbert problems, DETONATION waves
Abstract

Due to the complexity and short timescale of detonation, it is usually difficult to capture its transient characteristics experimentally. Advanced numerical methods are essential for enhancing the understanding of the flow field structure and combustion mechanism of detonation. In this study, a density-based compressible reactive flow solver called CDSFoam is developed for simulating gas-droplet two-phase detonation combustion based on OpenFOAM. The primary feature of this solver is its implementation of two-way coupling between gas and liquid phases, utilizing the Eulerian–Lagrangian method. The key enhancement is an improved approximate Riemann solver used to solve the convective flux, reducing dissipation while ensuring robustness. Time integration is achieved through the third-order strong stability preserving Runge–Kutta method. Additionally, CDSFoam incorporates dynamic load balancing and adaptive mesh refinement techniques to mitigate computational costs while achieving high-resolution flow fields dynamically. To validate the reliability and accuracy of the solver, a series of benchmark cases are examined, including the multi-component inert and reactive shock tube, the stable diffusion process, the Riemann problem, the one-dimensional detonation, the two-dimensional detonation and oblique detonation, the droplet phase model, the two-dimensional gas–liquid two-phase detonation, and the two-phase rotating detonation. The results show that CDSFoam can well predict the shock wave discontinuity, shock wave induced ignition, molecular diffusion, detonation key parameters, detonation cell size, and the main characteristics of gas–liquid two-phase detonation. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

36. Numerical study on flame acceleration and deflagration-to-detonation transition: Spatial distribution of solid obstacles.

Author

Wang, Jiabao, Li, Tong, Ji, Shaoqiu, Nie, Yunxi, Jiang, Xi Zhuo, and Zhu, Yuejin

Subjects
HEAT release rates, FLAME, HEAT of combustion, SHOCK waves, COMBUSTION chambers
Abstract

This study conducts a detailed numerical investigation on the spatial distribution of solid obstacles using the large eddy simulation method. It is discovered that although flame acceleration induced by solid obstacles is dominated by factors such as flow field disturbances, vortices and recirculation zones, turbulence, flame surface areas and combustion heat release rates, etc., the characteristics of the leading shock wave are key to detonation initiation. Specifically, the intensity of the leading shock wave, its formation time, and its distance from the flame front significantly affect detonation initiation. Depending on the state of the shock wave, the detonation initiation process may occur through various mechanisms such as shock reflection, shock focusing. Overall, the types of detonation initiation in this study all belong to the shock detonation transition. However, the detonation initiation process can be further classified into two categories: (I) Detonation induced by shock wave reflection; (II) detonation triggered by shock wave focusing. Despite certain disparities in the detonation initiation process, all detonation initiation processes conform to the gradient theory, and the flame evolution processes in all cases consistently follow three stages: the laminar slow-ignition stage; the turbulent deflagration stage; the detonation initiation stage. Furthermore, the study further discerns that, compared to positioning obstacles on the wall, placing obstacles inside the combustion chamber can further augment the detonation-assisting effect. However, excessively sparse or dense spatial distributions of solid obstacles fail to yield the optimal detonation effect. An optimal distribution exists, which triggers the fastest detonation initiation. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results