Query: : novel two-dimensional semiconductors with excellent stability and high electron mobility

Candidate papers:

abstract: Two dimensional materials play a vital role in next generation microelectronics, optoelectronics and flexible electronics due to their novel physical properties caused by quantum confinement effects. In this work, we investigate the stability and the possibility of exfoliation of monolayer Bi2Se3 xTex (x 0, 1, 2) using first principles calculations. Our calculations show that these materials are indirect bandgap semiconductors, and the elastic modulus is smaller than other conventional materials, which indicates better flexibility. We find that the electron mobility of monolayer Bi2SeTe2 along the armchair direction is higher than that of black phosphorene, reaching 2708 cm2 V 1 s 1, and the electron mobility of monolayer Bi2Se3 along the zigzag direction is about 24 times larger than the hole mobility. The remarkable electron mobilities and highly anisotropic properties of these new monolayers pave the way for future applications in high speed (opto)electronic devices.
author_names: Yifan Liu

Yuanfeng Xu

Yanjun Ji

Haitao Zhang
title: Monolayer Bi2Se3 xTex: novel two dimensional semiconductors with excellent stability and high electron mobility.
venue: Physical chemistry chemical physics PCCP
year: 2020

abstract: Photocatalytic water splitting is a promising method which uses sunlight to directly generate hydrogen from water to meet the requirements of energy consumption. Inspired by the experimental realization of monolayer b phase GeSe which has a moderate bandgap and excellent transport properties, based on the first principles calculations, we identify a new class of compelling two dimensional (2D) materials, b MX (GeS, GeSe, SnS and SnSe) which not only exhibit good feasibility for experimental exfoliation and excellent chemical stability, but also satisfy the bandgap and band edge requirements of the redox potential of water splitting. Excitingly, monolayer b GeSe and b SnSe exhibit remarkable optical absorption ability in the visible region, strongly anisotropic transport properties and a relatively small exciton binding energy of 0.50 eV (b GeSe) and 0.55 eV (b SnSe) favorable for the separation of photogenerated carriers (electrons and holes) The low overpotential in the oxygen evolution reaction and high overpotential in the hydrogen evolution reaction for monolayer b SnSe are attributed to the relatively large exciton binding energies, indicating that it can make a directional adjustment to the effective separation of photoexcited carriers for monolayer b SnSe. Therefore, we can expect a high photocatalytic activity for solar energy harvesting and water splitting for b GeSe and b SnSe monolayers.
author_names: Yuanfeng Xu

Ke Xu

Congcong Ma

Ying Chen

Haitao Zhang

Yifan Liu

Yanjun Ji
title: Novel two dimensional b GeSe and b SnSe semiconductors: anisotropic high carrier mobility and excellent photocatalytic water splitting
year: 2020

abstract: Two dimensional (2D) semiconductors with suitable direct band gaps, high carrier mobility, and excellent open air stability are especially desirable for material applications. Herein, we show theoretical evidence of a new phase of a copper(i) sulfide (Cu2S) monolayer, denoted d Cu2S, with both novel electronic properties and superior oxidation resistance. We find that both monolayer and bilayer d Cu2S have much lower formation energy than the known b Cu2S phase. Given that b Cu2S sheets have been recently synthesized in the laboratory (Adv. Mater.2016, 28, 8271) the higher stability of d Cu2S than that of b Cu2S sheets suggests a high possibility of experimental realization of d Cu2S. Stability analysis indicates that d Cu2S is dynamically and thermally stable. Notably, d Cu2S exhibits superior oxidation resistance, due to the high activation energy of 1.98 eV for the chemisorption of O2 on d Cu2S. On its electronic properties, d Cu2S is a semiconductor with a modest direct band gap (1.26 eV) and an ultrahigh electron mobility of up to 6880 cm2 V 1 s 1, about 27 times that (246 cm2 V 1 s 1) of the b Cu2S bilayer. The marked difference between the electron and hole mobilities of d Cu2S suggests easy separation of electrons and holes for solar energy conversion. Combination of these novel properties makes d Cu2S a promising 2D material for future applications in electronics and optoelectronics with high thermal and chemical stability.
author_names: Y Guo

Qisheng Wu

Yunhai Li

Ning Lu

Keke Mao

Yizhen Bai

Jijun Zhao

Jinlan Wang

Xiao Cheng Zeng
title: Copper(i) sulfide: a two dimensional semiconductor with superior oxidation resistance and high carrier mobility.
venue: Nanoscale horizons
year: 2019

abstract: It remains a pressing task to search for new two dimensional (2D) semiconducting materials for future generation electronic applications. By using density functional theory computations and global structure prediction methods, we demonstrate two new gold sulfide monolayers (2D Au2S and AuS) both exhibiting excellent electronic properties and high stabilities. All the gold sulfide monolayers are semiconductors with band gaps in the range 1.0 3.6 eV. In particular, the a Au2S monolayer is predicted to possess a direct band gap of 1.0 eV and extremely high electron and hole mobilities of 8.45 x 104 and 0.40 x 104 cm2 V 1 S 1, respectively. The phonon dispersion calculations and ab initio molecular dynamics simulations indicate that the gold sulfide monolayers exhibit robust dynamical and thermal stabilities. Moreover, the a Au2S monolayer appears to show strong oxidation resistibility. The novel electronic properties, coupled with structural and chemical stabilities, endow the new gold sulfide monolayers to be highly promising for future applications in nanoelectronics.
author_names: Qisheng Wu

Wen Wu Xu

Dongdong Lin

Jinlan Wang

Xiao Cheng Zeng
title: Two Dimensional Gold Sulfide Monolayers with Direct Band Gap and Ultrahigh Electron Mobility.
venue: The journal of physical chemistry letters
year: 2019

abstract: Two dimensional(2D) materials are considered excellent candidates for achieving a highly efficient photocatalyst. Herein, we report a novel 2D aluminum nitride monolayer (th AlN) as a potential photocatalyst material, possessing robust energetic, dynamical, thermal, and mechanical stability as well as strong stability in aqueuos conditions. The monolayer is an indirect band gap semiconductor at its equilibrium state and can induce an indirect to direct band gap transition under a very small strain 4% The band edge positions fit perfectly the water oxidation and reduction redox potentials. The monolayer exhibits strong visible ultraviolet light absorption, which is favorable for the efficient utilization of sunlight. The excellent electron transport ability including high and directionally anisotropic carrier mobility (104 cm2 V 1 s 1) leads to the rapid separation of electron hole pairs, retards the recombination of electron hole pairs, and greatly improves the photocatalytic activity. Furthermore, the monolayer exhibits exceptional mechanical properties including ultrahigh ideal strength (40% outperforming graphene, good flexibility, and mechanical anisotropy. Remarkably, the negative Poisson's ratio makes th AlN a promising candidate for auxetic materials. With these outstanding properties, th AlN can be considered as a promising candidate for potential application in the fields of electronics, optoelectronics, and nanomechanics.
author_names: Mehmet Emin Kilic
title: Auxetic, flexible, and strain tunable two dimensional th AlN for photocatalytic visible light water splitting with anisotropic high carrier mobility
year: 2021

abstract: Based on first principles calculations, we propose a novel two dimensional (2D) germanium carbide, tetrahex GeC2, and determine its electronic and optical properties. Each Ge atom binds to four C atoms, in contrast to the known 2D hexagonal germanium carbides. Monolayer tetrahex GeC2 possesses a narrow direct band gap of 0.89 eV, which can be effectively tuned by applying strain and increasing the thickness. Its electron mobility is extraordinarily high (9.5 x 104 cm2/(V s) about 80 times that of monolayer black phosphorus. The optical absorption coefficient is ~106 cm 1 in a wide spectral range from near infrared to near ultraviolet, comparable to perovskite solar cell materials. We obtain high cohesive energy (5.50 eV/atom) excellent stability, and small electron/hole effective mass (0.19/0.10 m0) Tetrahex GeC2 turns out to be a very promising semiconductor for nanoelectronic, optoelectronic, and photovoltaic applications.
author_names: Changchun Chai

Qingyang Fan

Minglei Sun

Yintang Yang

Udo Schwingenschlogl
title: Two Dimensional Tetrahex GeC2: A Material with Tunable Electronic and Optical Properties Combined with Ultrahigh Carrier Mobility
venue: ACS applied materials interfaces
year: 2021

abstract: Abstract The investigations of two dimensional photocatalysts are promising subjects in clean and renewable energy. Herein, we proposed a novel two dimensional GeN3 monolayer. The stability of GeN3 monolayer was examined via formation energy, phonon calculations and ab initio molecular dynamics simulations. Excellent photocatalytic properties are revealed: (a) GeN3 monolayer is a semiconductor with appropriate band gap of 1.962 eV that the valence and conduction bands straddle the redox potential of water. (b) GeN3 monolayer has extremely high carrier mobility with anisotropic character (its electron mobility is 1.55 x 104 cm2 V 1 s 1 along the armchair direction, whereas the hole mobility reaches 1.6 x 103 cm2 V 1 s 1 along the zigzag direction) which boost the separation of electron hole pairs. (c) The GeN3 monolayer shows strong light absorption coefficients (up to 105 cm 1) in the visible regions, leading to high solar to hydrogen efficiency (12.63 (d) Furthermore, the band gap of the GeN3 monolayer could be engineered from indirect to direct under external strain and electric field. This work discloses a novel 2D GeN3 monolayer whose fascinating properties make it a promising photocatalyst for hydrolyzing to produce hydrogen.
author_names: Jiajia Liu

Yanqing Shen

Xusheng Gao

Lingling Lv

Yanyan Ma

Shengyao Wu

Xinyu Wang

Zhongxiang Zhou
title: GeN3 monolayer: A promising 2D high efficiency photo hydrolytic catalyst with High carrier mobility transport anisotropy
year: 2020

abstract: We propose a novel two dimensional SnS allotrope (monolayer d SnS) based on an auxetic d phosphorene configuration using first principles calculations. This monolayer appears to have outstanding stability as revealed by its energetic, kinetic, thermodynamic, and mechanic calculations, and it can withstand temperatures as high as 900 K. Monolayer d SnS is a wide direct bandgap (2.354 eV) semiconductor, and its electron mobility is as high as ~1.25 x 103 cm2 V 1 s 1, higher than that of monolayer KTlO ~450 cm2 V 1 s 1) and MoS2 ~200 cm2 V 1 s 1) Optical absorption spectra, reaching up to the order of ~105 cm 1, are obviously excellent in the visible light region, suggesting efficient harvesting of solar radiation. Because of its unique atomic motif, monolayer d SnS presents an unusual bidirectional auxetic effect: a high negative in plane Poisson's ratio 0.048 and 0.068) which is larger than those for many recently reported two dimensional auxetic materials, e.g. black phosphorene 0.027) borophene 0.04) and monolayer penta B2N4 0.02) The bandgap and band edge can be substantially manipulated under strain to meet the requirement of the water splitting reaction. Particularly, when pH 7, suitable band edge alignments and small overpotentials of the photocatalytic OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) appear, endowing monolayer d SnS with great potential as an efficient visible light driven bifunctional photocatalyst for water splitting.
author_names: Xi'an Wang

Shali Yang
title: d SnS: An Emerging Bidirectional Auxetic Direct Semiconductor with Desirable Carrier Mobility and High Performance Catalytic Behavior toward the Water Splitting Reaction.
venue: ACS applied materials interfaces
year: 2021

abstract: Two dimensional (2D) materials have extraordinary properties and multifunctional applications; thus, prodigious efforts have been made in the exploration of novel 2D materials. In this study, 2D hexagonal YN (h YN) is predicted based on theoretical calculations. By assessing its phonon spectrum, ab initio molecular dynamics and elastic constants, the h YN monolayer is proven to exhibit satisfying thermal, dynamic and mechanical stability. Unique from most of the reported 2D transition metal mononitrides, which exhibit metallic characteristics, monolayer h YN is a semiconductor with an indirect bandgap of 2.322 eV. In particular, the electronic structures of h YN present unusually insensitive responses to tensile or compressive strain due to valence orbital hybridization. Carrier mobility calculations suggest that monolayer h YN possesses a high electron mobility of up to 104 cm2 V 1 s 1 and hole mobility of up to 103 cm2 V 1 s 1 in the zigzag and armchair orientations. Moreover, few layer h YN displays evident semiconductor performances and dispersive conductive bands, indicating light electron effective masses and excellent electron transport capabilities. This pronounced carrier mobility, insensitive electronic responses to strain and light electron effective masses of its few layer structures demonstrate that h YN is a promising candidate in future nanoscale electronic devices in high strain conditions.
author_names: Kai Zheng

Xi-bin Yang

Heping Cui

Qun Yang

Huaiyu Ye

Daxi Xiong

Sven Ingebrandt

Xianping Chen
title: Intriguing electronic insensitivity and high carrier mobility in monolayer hexagonal YN
year: 2018

abstract: Abstract.Exploring new 2D monolayer materials with intrinsic novel properties is of great significance from both fundamental and practical points of view. Using first principles calculations based on density functional theory, we propose three stable hexagonal SiAs monolayers with the excellent thermal and dynamic stabilities, whose crystal structures are similar to the monolayer GaSe, named \alpha$a \beta$b and \gamma$g SiAs, respectively. Our results show that \alpha$a and \beta$b SiAs monolayers are wide band gap semiconductors with indirect band gaps, which have great potential applications in photoelectronic devices, especially used for catalytic splitting water. Further, the effective masses of electron transport in monolayers \alpha$a and \beta$b SiAs exhibit anisotropic characteristics. Intriguingly, \gamma$g SiAs is a direct band gap semiconductor with a band gap of 1.13eV as bulk silicon, which results in a significant absorption in the visible light region. More importantly, the effective masses in the \gamma$g SiAs monolayer are only a little larger than 0.20 m0, indicating that it may have high carrier mobility. Our findings provide three promising candidates for low dimensional nanodevices with excellent performances in the future.
author_names: Xinliang Wang

Guang-Wei Deng

Weiyang Yu

Baoji Wang

Xiao-hua Li

Yujin Liu

Yu-huan Zhao

Qin Wang

Liwei Zhang

Xiao-lin Cai
title: A class of two dimensional SiAs monolayers with novel electronic and optical properties from ab initio investigations
venue: The European Physical Journal Plus
year: 2019