Heterodyne transient vibrational SFG to reveal molecular responses to interfacial charge transfer
Heterodyne transient vibrational SFG to reveal molecular responses to interfacial charge transfer
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DOI：
10.1063/1.5066237
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发表时间：
2019-03-21
影响因子：
4.4
通讯作者：
Xiong, Wei
中科院分区：
文献类型：
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作者：
Li, Yingmin;Xiang, Bo;Xiong, Wei
我们证明外差检测瞬态振动和频产生（VSFG）光谱，并用它来探测瞬态电场所造成的界面电荷转移在有机半导体和金属界面。静态和瞬态VSFG谱由非共振和分子共振响应组成。为了进一步解开这两个贡献，我们应用相位旋转，使光谱的虚部是纯粹的分子响应和光谱的真实的部分由非共振信号主导。通过分离非共振信号和分子信号，我们可以独立地跟踪它们对界面瞬态电场的响应。这种技术结合外差检测获得的相位灵敏度，使我们能够成功地确定三种类型的光致动力学在有机半导体/金属界面：相干文物，光学激发，不导致电荷转移，和直接的电荷转移。无论强非共振信号如何，单独跟踪内置电场对界面分子的影响的能力将能够跟踪分子光电子学，光电子学和太阳能材料上具有分子特异性的超快电荷动力学。由AIP Publishing授权出版。
We demonstrate heterodyne detected transient vibrational sum frequency generation (VSFG) spectroscopy and use it to probe transient electric fields caused by interfacial charge transfer at organic semiconductor and metal interfaces. The static and transient VSFG spectra are composed of both non-resonant and molecular resonant responses. To further disentangle both contributions, we apply phase rotation to make the imaginary part of the spectra be purely molecular responses and the real part of the spectra be dominated by non-resonant signals. By separating non-resonant and molecular signals, we can track their responses to the transient electric-fields at interfaces independently. This technique combined with the phase sensitivity gained by heterodyne detection allows us to successfully identify three types of photoinduced dynamics at organic semiconductor/metal interfaces: coherent artifacts, optical excitations that do not lead to charge transfer, and direct charge transfers. The ability to separately follow the influence of built-in electric fields to interfacial molecules, regardless of strong non-resonant signals, will enable tracking of ultrafast charge dynamics with molecular specificities on molecular optoelectronics, photovoltaics, and solar materials. Published under license by AIP Publishing.