Semiconductor Physics, Chemnitz University of Technology, Chemnitz, Germany.
A.V. Rzhanov Institute of Semiconductor Physics, Novosibirsk, Russia.
J Chem Phys. 2020 Oct 28;153(16):164708. doi: 10.1063/5.0025572.
Semiconducting nanoplatelets (NPLs) have attracted great attention due to the superior photophysical properties compared to their quantum dot analogs. Understanding and tuning the optical and electronic properties of NPLs in a plasmonic environment is a new paradigm in the field of optoelectronics. Here, we report on the resonant plasmon enhancement of light emission including Raman scattering and photoluminescence from colloidal CdSe/CdS nanoplatelets deposited on arrays of Au nanodisks fabricated by electron beam lithography. The localized surface plasmon resonance (LSPR) of the Au nanodisk arrays can be tuned by varying the diameter of the disks. In the case of surface-enhanced Raman scattering (SERS), the Raman intensity profile follows a symmetric Gaussian shape matching the LSPR of the Au nanodisk arrays. The surface-enhanced photoluminescence (SEPL) profile of NPLs, however, follows an asymmetric Gaussian distribution highlighting a compromise between the excitation and emission enhancement mechanisms originating from energy transfer and Purcell effects. The SERS and SEPL enhancement factors depend on the nanodisk size and reach maximal values at 75 and 7, respectively, for the sizes, for which the LSPR energy of Au nanodisks coincides with interband transition energies in the semiconductor platelets. Finally, to explain the origin of the resonant enhancement behavior of SERS and SEPL, we apply a numerical simulation to calculate plasmon energies in Au nanodisk arrays and emission spectra from NPLs in such a plasmonic environment.
半导体纳米板（NPLs）由于其与量子点类似物相比具有优越的光物理性质而受到极大关注。在等离子体环境中理解和调节 NPL 的光学和电子性质是光电领域的一个新范例。在这里，我们报告了胶体 CdSe/CdS 纳米板在通过电子束光刻制造的 Au 纳米盘阵列上沉积时的光致发光包括拉曼散射和光致发光的共振等离子体增强。Au 纳米盘阵列的局域表面等离子体共振（LSPR）可以通过改变盘的直径来调节。在表面增强拉曼散射（SERS）的情况下，拉曼强度分布遵循与 Au 纳米盘阵列的 LSPR 匹配的对称高斯形状。然而，NPL 的表面增强光致发光（SEPL）分布遵循非对称高斯分布，突出了源自能量转移和 Purcell 效应的激发和发射增强机制之间的折衷。SERS 和 SEPL 的增强因子取决于纳米盘的尺寸，对于 Au 纳米盘的尺寸，当 LSPR 能量与半导体板中的带间跃迁能量相吻合时，增强因子达到最大值，分别为 75 和 7。最后，为了解释 SERS 和 SEPL 的共振增强行为的起源，我们应用数值模拟来计算 Au 纳米盘阵列中的等离子体能量和在这种等离子体环境中 NPL 的发射光谱。
