arXiv subjects

Yu-Hsiu Lin

Publications and source records attributed to Yu-Hsiu Lin.

5 recordsLinked to original sources

arXiv2025

A first-principles theoretical study on two-dimensional MX and MX$_2$ metal halides: bandgap engineering, magnetism, and catalytic descriptors

Metal halides, particularly MX and MX$_2$ compounds (where M represents metal elements and X = F, Cl, Br, I), have attracted significant interest due to their diverse electronic and optoelectronic properties. However, a comprehensive understanding of their structural and electronic behavior, particularly the evolution of these properties from bulk to low-dimensional forms, remains limited. To address this gap, we performed first-principles calculations to develop a database of 60 MX and MX$_2$ metal halides, detailing their structural and electronic properties in both bulk and slab configurations. Calculations were performed using the advanced \texttt{HSE06-D3} hybrid functional for density functional theory (DFT), ensuring high precision in predicting material properties despite the associated computational cost. The results reveal that these materials are predominantly semiconductors, but their bandgaps range from 0 to 9 eV. A detailed analysis of the transition from bulk to slab structures highlights notable shifts in electronic properties, including bandgap modifications. Upon dimensional reduction, 9 materials exhibit an indirect-to-direct bandgap transition, enhancing their potential for energy conversion. Beyond structural dimensionality, the influence of chemical composition on bandgap variations was also examined. To further assess their practical applicability, the catalytic and magnetic properties of these metal halides were systematically evaluated. These findings not only illuminate previously underexplored MX and MX$_2$ metal halides but also identify promising candidates for electronic, optoelectronic, catalytic and spintronic applications. This database serves as a valuable resource for guiding future research and technology development in low-dimensional materials.

cond-mat.mtrl-sci↗

arXiv2024

Beyond Lithium-Ion Batteries: Are Effective Electrodes Possible for Alkaline and Other Alkali Elements? Exploring Ion Intercalation in Surface-Modified Few-Layer Graphene and Examining Layer Quantity and Stages

In the quest for better energy storage solutions, the role of designing effective electrodes is crucial. Previous research has shown that using materials like single-side fluorinated graphene can improve the stability of ion insertion in few-layer graphene (FLG), which is vital as we move beyond lithium-ion batteries. Alternatives such as sodium and potassium, which are more abundant on Earth, appear promising, but thorough studies on how these ions insert into electrodes in stages are still needed. Our research focuses on the initial three alkali (Li, Na, K) and alkaline (Be, Mg, Ca) earth metals. Using Density Functional Theory (DFT) with advanced calculations, we've investigated how these ions interact with modified graphene at various stages of insertion. This method provides more precise electrical data and has helped us understand the complex interactions involved. Specifically, we found a new site for ion insertion that is energetically favorable. We also explored how modifying the graphene surface affects ions of different sizes and charges and examined how the number of graphene layers influences these interactions. Our discoveries are crucial for developing new materials that could replace lithium-ion batteries and provide a foundation for adjusting electrical properties in battery design through ion staging and surface modifications.

cond-mat.mtrl-sci↗

arXiv2024

How Can We Engineer Electronic Transitions Through Twisting and Stacking in TMDC Bilayers and Heterostructures? A First-Principles Approach

Layered two-dimensional (2D) materials exhibit unique properties, expanding opportunities in material design. We investigate MX$_2$ transition metal dichalcogenides (TMDCs) (M = Mo, W; X = S, Se, Te) in homo- and heterobilayers with different stacking and twist angles. Twisted bilayers introduce Moir\'e patterns, significantly altering electronic properties. Using first-principles Density Functional Theory (DFT) with range-separated hybrid functionals, we examine 30 MX$_2$ combinations, revealing how stacking and composition influence stability and band gap energy (E$_g$). Notably, the MoTe$_2$/WSe$_2$ heterostructure with a 60\textdegree~shift maintains a direct band gap, highlighting its potential for applications. Homobilayers under low-strain conditions exhibit diverse stacking-dependent electronic behaviors, where MoS$_2$, WS$_2$, and WSe$_2$ transition between direct and indirect band gaps at specific twist angles. MoS$_2$ can even switch between semiconductor and metallic states. Critical twist angles (17.9\textdegree, 42.1\textdegree, 77.9\textdegree, and 102.1\textdegree) in twisted WS$_2$ and WSe$_2$ bilayers yield symmetric Moir\'e patterns with tunable band gaps. Our findings emphasize that controlling heterostructures and twist angles is a powerful strategy for engineering electronic properties, offering a pathway for next-generation materials.

cond-mat.mtrl-sci↗

arXiv2023

Transforming Materials Discovery for Artificial Photosynthesis: High-Throughput Screening of Earth-Abundant Semiconductors

We present a highly efficient workflow for designing semiconductor structures with specific physical properties, which can be utilized for a range of applications, including photocatalytic water splitting. Our algorithm generates candidate structures composed of earth-abundant elements that exhibit optimal light-trapping, high efficiency in \ce{H2} and/or \ce{O2} production, and resistance to reduction and oxidation in aqueous media. To achieve this, we use an ionic translation model trained on the Inorganic Crystal Structure Database (ICSD) to predict over thirty thousand undiscovered semiconductor compositions. These predictions are then screened for redox stability under Hydrogen Evolution Reaction (HER) or Oxygen Evolution Reaction (OER) conditions before generating thermodynamically stable crystal structures and calculating accurate band gap values for the compounds. Our approach results in the identification of dozens of promising semiconductor candidates with ideal properties for artificial photosynthesis, offering a significant advancement toward the conversion of sunlight into chemical fuels.

physics.app-ph↗

arXiv2012

Graph-based Code Design for Quadratic-Gaussian Wyner-Ziv Problem with Arbitrary Side Information

Wyner-Ziv coding (WZC) is a compression technique using decoder side information, which is unknown at the encoder, to help the reconstruction. In this paper, we propose and implement a new WZC structure, called residual WZC, for the quadratic-Gaussian Wyner-Ziv problem where side information can be arbitrarily distributed. In our two-stage residual WZC, the source is quantized twice and the input of the second stage is the quantization error (residue) of the first stage. The codebook of the first stage quantizer must be simultaneously good for source and channel coding, since it also acts as a channel code at the decoder. Stemming from the non-ideal quantization at the encoder, a problem of channel decoding beyond capacity is identified and solved when we design the practical decoder. Moreover,by using the modified reinforced belief-propagation quantization algorithm, the low-density parity check code (LDPC), whose edge degree is optimized for channel coding, also performs well as a source code. We then implement the residual WZC by an LDPC and a low density generator matrix code (LDGM). The simulation results show that our practical construction approaches the Wyner-Ziv bound. Compared with previous works, our construction can offer more design lexibility in terms of distribution of side information and practical code rate selection.

cs.IT↗