Influence of Band Alignment on Electronic Relaxation in Plasmonic Metal–Semiconductor Hybrid Nanoparticles
Influence of Band Alignment on Electronic Relaxation in Plasmonic Metal–Semiconductor Hybrid Nanoparticles
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DOI：
10.1021/acs.jpcc.2c01378
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发表时间：
2022-05
期刊：
影响因子：
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通讯作者：
William R. Jeffries;A. Fagan;R. Schaak;K. Knappenberger
中科院分区：
文献类型：
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作者：
William R. Jeffries;A. Fagan;R. Schaak;K. Knappenberger
胶体合成的最新进展使得能够产生共享固态界面的多组分金属-半导体纳米颗粒，从而为定制的纳米级异质结构的电子和光学性质提供了一个可调的平台。本文利用飞秒时间分辨消光光谱研究了金-金属硫化物(PbS、ZnS和Cu2-XS)杂化纳米粒子的尺寸和材料组成对电子-声子散射的影响。采用不同PbS直径(6±1 nm和17±3 nm)的Au-PbS体系，研究了半导体尺寸对杂化纳米粒子电声耦合的影响。对于Au-PbS(PbS=6±1 nm)，相对于5±1 nm的金纳米粒子，电子-声子散射率提高了约30%。相反，与金纳米粒子相比，具有较大PBS结构域大小的系统表现出减速。电子-声子散射率对纳米结构的依赖归因于能带边缘相对于Au-Fermi能级排列的差异。Au-Cu2-Xs的电子-声子散射被加速，其中导带边缘与金费米能级紧密对准。相反，Au-ZnS的超快响应与纯AuNPs没有显著差异，这与两个磁区之间的最小能量排列一致，在这种情况下，ZnS磁区是一个有效的绝缘体。这些结果表明，对金属-半导体杂化纳米粒子中半导体区的大小和组成进行可控和选择性的修饰会影响能带排列，这反过来可以被用来调节等离子体支持的异质结构中的电子热化。
Recent advances in colloidal synthesis enable the generation of multicomponent metal–semiconductor nanoparticles that share a solid-state interface, thus providing a tunable platform for the tailored electronic and optical properties of nanoscale heterostructures. Here, the influence of size and material composition on electron–phonon scattering was investigated for a series of gold–metal chalcogenide (PbS, ZnS, and Cu2–xS) hybrid nanoparticles using femtosecond time-resolved transient extinction spectroscopy. The influence of semiconductor size on electron–phonon coupling in the hybrid nanoparticles was studied using two Au–PbS systems having different PbS diameters, 6 ± 1 and 17 ± 3 nm. For Au–PbS (PbS = 6 ± 1 nm), an approximately 30% acceleration of the electron–phonon scattering rate was observed with respect to 5 ± 1 nm gold nanoparticles. In contrast, the system having the larger PbS domain size exhibited a decelerated rate when compared to gold nanoparticles. The nanostructure dependence of the electron–phonon scattering rates was attributed to differences in band edge alignment with respect to the Au Fermi level. Electron–phonon scattering was accelerated for Au–Cu2–xS where the conduction band edge is in close alignment with the gold Fermi level. In contrast, the ultrafast response of Au–ZnS displayed no significant difference from pure AuNPs, which is consistent with minimal energy alignment between the two domains; the ZnS domain is an effective insulator in this case. These results demonstrate that controlled and selective modifications to both the size and composition of the semiconductor domain in metal–semiconductor hybrid nanoparticles impact band alignment, which in turn can be leveraged to modulate electronic thermalization in plasmon-supporting heterostructures.