Anomalous pressure-dependence in surface-modified silicon-derived nanoparticles
Anomalous pressure-dependence in surface-modified silicon-derived nanoparticles
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DOI：
10.1007/s12274-021-3418-3
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发表时间：
2021-05
期刊：
影响因子：
9.9
通讯作者：
Qi Li;Abhinav Parakh;Rongchao Jin;X. Gu
中科院分区：
文献类型：
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作者：
Qi Li;Abhinav Parakh;Rongchao Jin;X. Gu
表面可以显著改变纳米材料的光学性质，但它们很难控制，在高活性材料(如硅纳米材料)中的作用也很难理解。在这项工作中，我们研究了表面在高发光硅源纳米颗粒中控制光学跃迁的作用。通过高压和低温相结合的实验，我们从实验上将紫外光谱中异常强烈和狭窄的跃迁与表面氧化物关联起来，而可见跃迁和光致发光(PL)则被证实来自于硅配体的电荷转移带。我们发现，高压吸收和发光依赖于表面配体的刚性。这表明表面对这些硅基纳米粒子的光学性质起着主导作用，并且不同于其他半导体纳米材料，在这些半导体纳米材料中，压力相关的光学转变依赖于晶格应变或相变。这项工作全面了解了这些高发光硅源纳米粒子的光学跃迁以及表面配体和表面氧化的影响。对氧化激活和配体介导的跃迁的新见解，以及依赖于压力的发光，可能有助于设计其他高活性光学纳米材料的能带结构。
Surfaces can significantly alter the optical properties of nanomaterials, but they are difficult to control and their roles are hard to understand in highly reactive materials such as silicon nanomaterials. In this work, we investigate the role of the surface in controlling the optical transitions in highly luminescent silicon-derived nanoparticles. By combining high-pressure and low-temperature experiments, we experimentally correlate the anomalously intense and narrow transitions in the UV range with the surface oxides, while the visible transition and the photoluminescence (PL) are verified to originate from the Si-ligand charge transfer band. We find that the high-pressure absorption and PL depends on the rigidity of the surface ligand. This indicates that the surface plays a dominant role on the optical properties of these silicon-derived nanoparticles, and is different than other semiconductor nanomaterials, in which pressure-dependent optical transitions depend on lattice strain or phase transformations. This work presents a comprehensive understanding of the optical transitions and the effect of surface ligands and surface oxidation in these highly luminescent Si-derived nanoparticles. The new insight into the oxidation-activated and ligand-mediated transitions, and the pressure-dependent PL may help with engineering the band structure of other highly-reactive optical nanomaterials.