Two-dimensional(2D)transition metal dichalcogenides(TMDs)and their heterostructures(HSs)exhibit unique optical properties and show great promise for developing next-generation optoelectronics.However,the photo-lumines...Two-dimensional(2D)transition metal dichalcogenides(TMDs)and their heterostructures(HSs)exhibit unique optical properties and show great promise for developing next-generation optoelectronics.However,the photo-luminescence(PL)quantum yield of monolayer(1L)TMDs is still quite low at room temperature,which severely lim-its their practical applications.Here we report a PL enhancement effect of 1L WS_(2) at room temperature when con-structing it into 1L-WS_(2)/hBN/1L-MoS_(2) vertical HSs.The PL enhancement factors(EFs)can be up to 4.2.By using transient absorption(TA)spectroscopy,we demonstrate that the PL enhancement effect is due to energy transfer from 1L MoS_(2) to 1L WS_(2).The energy transfer process occurs on a picosecond timescale and lasts more than one hundred picoseconds which indicates a prominent contribution from exciton-exciton annihilation.Furthermore,the PL en-hancement effect of 1L WS_(2) can be observed in 2L-MoS_(2)/hBN/1L-WS_(2) and 3L-MoS_(2)/hBN/1L-WS_(2) HSs.Our study provides a comprehensive understanding of the energy transfer process in the PL enhancement of 2D TMDs and a fea-sible way to optimize the performance of TMD-based optoelectronic devices.展开更多
在MP2/aug-cc-pvtz水平上对SiH4…Y(Y=He,Ne,Ar,Kr)复合物势能面上的4个构型进行优化,探讨了SiH4…Y(Y=Ar,Kr)复合物体系中的蓝移氢键结构和电子性质.含基组重叠误差(BSSE)校正的分子间相互作用能的相对大小可以判断复合物的相对稳定性...在MP2/aug-cc-pvtz水平上对SiH4…Y(Y=He,Ne,Ar,Kr)复合物势能面上的4个构型进行优化,探讨了SiH4…Y(Y=Ar,Kr)复合物体系中的蓝移氢键结构和电子性质.含基组重叠误差(BSSE)校正的分子间相互作用能的相对大小可以判断复合物的相对稳定性递增顺序为:SiH4…He→SiH4…Ne→SiH4…Ar≈SiH4…Kr.且SiH4与Y(Y=He,Ne)体系之间的相互作用可归属为van der Waals力,而SiH4与Y(Y=Ar,Kr)之间的相互作用属弱氢键.NBO及电子行为分显示,SiH4…Y(Y=Ar,Kr)氢键复合物是一种非静电性质的弱氢键作用.另外,对各复合物中相关键鞍点处的电子密度拓扑性质分析也表明复合物中均存在非静电性质的分子间弱相互作用.展开更多
二维材料过渡金属硫属化物(TMDs),因其优越的物理化学特性及其在光电子器件、光催化等领域的潜在应用价值,得到了人们的广泛关注。基于TMDs材料可以构建具有不同性能的范德华(vdW)异质结,但构建的异质结由于其固有的能带带隙大小限制了...二维材料过渡金属硫属化物(TMDs),因其优越的物理化学特性及其在光电子器件、光催化等领域的潜在应用价值,得到了人们的广泛关注。基于TMDs材料可以构建具有不同性能的范德华(vdW)异质结,但构建的异质结由于其固有的能带带隙大小限制了其在全光谱上的响应,因而对其能带带隙调控变得十分重要。本文基于第一性原理方法系统地研究了WX_2 (X=S, Se, Te)从单层到体相的结构和性质,以及由此组装的vdW异质结构WS_2/WSe_2、WS_2/WTe_2和WSe_2/WTe_2的结构和性质以及应力应变对异质结构的能带带隙的影响。结果表明:结合HSE06泛函和自旋轨道耦合(SOC)效应的计算方案可以精确描述WX_2体系;异质结构WS_2/WSe_2,WS_2/WTe_2和WSe_2/WTe_2呈现type-II能带分类;在施加单轴或双轴的应力应变后,能带带隙大小发生相应改变,当晶格形变大于4%后,异质结构由半导体特性变成具有金属性。这些研究为光电子器件的设计提供了重要的指导意义。展开更多
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDs)and their heterostructures(HSs)exhibit unique optical properties and show great promise for developing next-generation optoelectronics.However,the photo-luminescence(PL)quantum yield of monolayer(1L)TMDs is still quite low at room temperature,which severely lim-its their practical applications.Here we report a PL enhancement effect of 1L WS_(2) at room temperature when con-structing it into 1L-WS_(2)/hBN/1L-MoS_(2) vertical HSs.The PL enhancement factors(EFs)can be up to 4.2.By using transient absorption(TA)spectroscopy,we demonstrate that the PL enhancement effect is due to energy transfer from 1L MoS_(2) to 1L WS_(2).The energy transfer process occurs on a picosecond timescale and lasts more than one hundred picoseconds which indicates a prominent contribution from exciton-exciton annihilation.Furthermore,the PL en-hancement effect of 1L WS_(2) can be observed in 2L-MoS_(2)/hBN/1L-WS_(2) and 3L-MoS_(2)/hBN/1L-WS_(2) HSs.Our study provides a comprehensive understanding of the energy transfer process in the PL enhancement of 2D TMDs and a fea-sible way to optimize the performance of TMD-based optoelectronic devices.
文摘在MP2/aug-cc-pvtz水平上对SiH4…Y(Y=He,Ne,Ar,Kr)复合物势能面上的4个构型进行优化,探讨了SiH4…Y(Y=Ar,Kr)复合物体系中的蓝移氢键结构和电子性质.含基组重叠误差(BSSE)校正的分子间相互作用能的相对大小可以判断复合物的相对稳定性递增顺序为:SiH4…He→SiH4…Ne→SiH4…Ar≈SiH4…Kr.且SiH4与Y(Y=He,Ne)体系之间的相互作用可归属为van der Waals力,而SiH4与Y(Y=Ar,Kr)之间的相互作用属弱氢键.NBO及电子行为分显示,SiH4…Y(Y=Ar,Kr)氢键复合物是一种非静电性质的弱氢键作用.另外,对各复合物中相关键鞍点处的电子密度拓扑性质分析也表明复合物中均存在非静电性质的分子间弱相互作用.
文摘二维材料过渡金属硫属化物(TMDs),因其优越的物理化学特性及其在光电子器件、光催化等领域的潜在应用价值,得到了人们的广泛关注。基于TMDs材料可以构建具有不同性能的范德华(vdW)异质结,但构建的异质结由于其固有的能带带隙大小限制了其在全光谱上的响应,因而对其能带带隙调控变得十分重要。本文基于第一性原理方法系统地研究了WX_2 (X=S, Se, Te)从单层到体相的结构和性质,以及由此组装的vdW异质结构WS_2/WSe_2、WS_2/WTe_2和WSe_2/WTe_2的结构和性质以及应力应变对异质结构的能带带隙的影响。结果表明:结合HSE06泛函和自旋轨道耦合(SOC)效应的计算方案可以精确描述WX_2体系;异质结构WS_2/WSe_2,WS_2/WTe_2和WSe_2/WTe_2呈现type-II能带分类;在施加单轴或双轴的应力应变后,能带带隙大小发生相应改变,当晶格形变大于4%后,异质结构由半导体特性变成具有金属性。这些研究为光电子器件的设计提供了重要的指导意义。
基金supported by the National Natural Science Foundation of China (51972170)the State Key Laboratory of MaterialsOriented Chemical Engineering (SKL-MCE-23A04)+3 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the Jiangsu Specially-Appointed Professor Program. CHEN Zhi-gang thanks the financial support from the Australian Research Council, and QUT Capacity Building Professor Programsupport from the Chongqing Research Program of Basic Research and Frontier Technology (cstc2021jcyj-msxm X0641)the Doctoral “through train” scientific research project of Chongqing (CSTB2022BSXM-JCX0085).
