Superatom Molecular Orbital as an Interfacial Charge Separation State,The Journal of Physical Chemistry Letters

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Superatom Molecular Orbital as an Interfacial Charge Separation State
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2018-06-05 00:00:00 , DOI: 10.1021/acs.jpclett.8b01302
Hongli Guo _{1,

2} , Chuanyu Zhao ₂ , Qijing Zheng ₂ , Zhenggang Lan ₃ , Oleg V. Prezhdo ₄ , Wissam A. Saidi ₅ , Jin Zhao _{2,

6,

7}

Affiliation

Hot electron cooling by energy loss to heat through electron–phonon (e–ph) interaction is an important mechanism that can limit the efficiency of solar energy conversion. To avoid such energy loss, sufficient charge separation needs to be realized by extracting hot carriers from the photoconverter before they cool, which requires fast interfacial charge transfer and slow internal hot carrier relaxation. Using ab initio time-dependent nonadiabatic molecular dynamics and taking C₆₀/MoS₂ as a prototype system, we show that the superatom molecular orbitals (SAMOs) of fullerenes, which are bound by the central potential of the whole molecule induced by the charge screening, are ideal media for charge separation. The diffuse character of SAMOs results in extremely weak e–ph interaction and therefore acts as a “phonon bottleneck” for hot electron cooling. Furthermore, it also leads to significant hybridization with other atoms at the interface that induces fast charge transfer. The interfacial charge-transfer rate at the C₆₀/MoS₂ interface is found to be 2 orders of magnitude faster than the hot electron cooling from s-SAMO in C₆₀. This conclusion is generally applicable for different carbon nanostructures that have SAMOs. The proposed SAMO-induced charge separation provides unique and essential insights into the material design and function for solar energy conversion.

中文翻译：

超原子分子轨道作为界面电荷的分离状态

通过能量损失通过电子-声子（e-ph）相互作用将热电子冷却的热量是限制太阳能转换效率的重要机制。为了避免这种能量损失，需要通过在热转换器冷却之前从热转换器中提取热载流子来实现足够的电荷分离，这需要快速的界面电荷转移和缓慢的内部热载流子松弛。使用从头开始随时间变化的非绝热分子动力学，并采用C ₆₀ / MoS ₂作为原型系统，我们表明富勒烯的超原子分子轨道（SAMO）受电荷筛选诱导的整个分子的中心电势约束，是理想的电荷分离介质。SAMO的扩散特性导致e-ph相互作用极弱，因此成为热电子冷却的“声子瓶颈”。此外，它还导致在界面上与其他原子的显着杂交，从而引起快速电荷转移。发现在C ₆₀ / MoS ₂界面处的界面电荷转移速率比在C _60中从s -SAMO进行的热电子冷却快2个数量级。。该结论通常适用于具有SAMO的不同碳纳米结构。拟议中的SAMO诱导的电荷分离为太阳能转换的材料设计和功能提供了独特而必不可少的见解。

更新日期：2018-06-05

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