Plasmonic coupling at a metal/semiconductor interface
Plasmonic coupling at a metal/semiconductor interface
复制标题
金属/半导体界面的等离子体耦合
DOI：
10.1038/s41566-017-0049-4
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发表时间：
2017-12-01
期刊：
影响因子：
35
通讯作者：
Petek, Hrvoje
中科院分区：
文献类型：
--
作者：
Tan, Shijing;Argondizzo, Adam;Petek, Hrvoje
等离子体纳米粒子与半导体衬底的集成引入了强光学共振，扩展和增强了光催化和光伏活性的光谱。基于增强光活性的作用谱，等离子体共振的影响被不同地归因于场纳米约束、等离子体激子耦合、热电子转移等。然而，目前尚不清楚的是，衬底中的带电载流子是由等离子体产生的热电子从金属中转移而产生的，还是由界面处等离子体场的消相直接产生的。在这里，我们通过双光子光电发射光谱直接探测相干性和热电子动力学，证明了在典型的银纳米簇/ tio2异质结上，化学界面上直接等离子体耦合对热电子产生的重要性。Ag纳米团簇/ tio2异质结中激发的能量、时间和材料分布表明，介质与衬底的耦合使Ag纳米粒子的等离子体共振重新正规化，其消相在<10 fs的时间尺度上直接在tio2中产生热电子。
Integrating plasmonic nanoparticles with semiconductor substrates introduces strong optical resonances that extend and enhance the spectrum of photocatalytic and photovoltaic activity. The effect of plasmonic resonances has been variously attributed to the field nanoconfinement, plasmon–exciton coupling, hot electron transfer, and so on, based on action spectra of enhanced photoactivity. It remains unclear, however, whether energized carriers in the substrate are generated by the transfer of plasmonically generated hot electrons from the metal, as broadly believed, or directly by dephasing of the plasmonic field at the interface. Here, we demonstrate the importance of the direct plasmonic coupling across the chemical interface for hot electron generation at a prototypical Ag nanocluster/TiO2heterojunction by direct probing of the coherence and hot electron dynamics with two-photon photoemission spectroscopy. Energy, time and material distributions of excitations in the Ag nanocluster/TiO2heterojunction indicate that dielectric coupling with the substrate renormalizes the plasmon resonance of the Ag nanoparticle, and its dephasing directly generates hot electrons in TiO2on a <10 fs timescale.