Disparity in Photoexcitation Dynamics between Vertical and Lateral MoS2/WSe2 Heterojunctions: Time-Domain Simulation Emphasizes the Importance of Donor-Acceptor Interaction and Band Alignment.
Disparity in Photoexcitation Dynamics between Vertical and Lateral MoS2/WSe2 Heterojunctions: Time-Domain Simulation Emphasizes the Importance of Donor-Acceptor Interaction and Band Alignment.
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DOI：
10.1021/acs.jpclett.7b02779
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发表时间：
2017-11
期刊：
影响因子：
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通讯作者：
Yating Yang;W. Fang;R. Long
中科院分区：
文献类型：
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作者：
Yating Yang;W. Fang;R. Long
二维过渡金属二硫属化合物异质结在光电子学和光电子学领域有着广泛的应用前景。使用时域密度泛函理论结合非绝热（NA）分子动力学，我们表明，光激发动力学表现出显着的差异，在垂直和横向的MoS 2/WSe 2异质结所产生的差距在施主-受主相互作用和基本能带排列。所得到的垂直异质结中的电子转移时间尺度与实验结果吻合得很好。空穴传输速度慢1.5倍。电子-空穴复合比电荷分离长3个数量级，这有利于太阳能电池应用。相反，横向异质结显示没有带偏移转向电荷分离。受激电子局域在界面处，由于库仑相互作用而吸引空穴形成类激子态，这表明在发光器件中有潜在的应用。与垂直情况相比，耦合的电子和空穴波函数增加了NA耦合和相干时间，加速了电子-空穴复合的3倍。原子论的研究进一步加深了我们对TMDs异质结中光生电荷-声子动力学的理解。
Two-dimensional transition metal dichalcogenides (TMDs) heterojunctions are appealing candidates for optoelectronics and photovoltaics. Using time-domain density functional theory combined with nonadiabatic (NA) molecular dynamics, we show that photoexcitation dynamics exhibit a significant difference in the vertical and lateral MoS2/WSe2 heterojunctions arising from the disparity in the donor-acceptor interaction and fundamental band alignment. The obtained electron transfer time scale in the vertical heterojunction shows excellent agreement with experiment. Hole transfer proceeds 1.5 times slower. The electron-hole recombination is 3 orders of magnitude longer than the charge separation, which favors solar cell applications. On the contrary, the lateral heterojunction shows no band offsets steering charge separation. The excited electron is localized at the interface that attracts holes to form an exciton-like state due to Coulomb interaction, suggesting potential applications in light-emitting devices. The coupled electron and hole wave functions increase NA coupling and the coherence time, accelerating electron-hole recombination by a factor of 3 compared with the vertical case. The atomistic studies advance our understanding of the photoinduced charge-phonon dynamics in TMDs heterojunctions.