School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.
Nanoscale. 2018 Aug 23;10(33):15600-15607. doi: 10.1039/c8nr05071f.
The creation of multiple emission pathways in quantum dots (QDs) is an exciting prospect with fundamental interest and optoelectronic potential. For the first time, we report multiple emission pathways in semiconductor nanocrystals (NCs) where the number of emission pathways desired is controlled by the number of dopant atoms per quantum dot. The origin of additional emission pathways is explained by interactions between dopant states and NC energy levels. Density functional theory (DFT) calculations of undoped 2.3 nm silicon (Si NCs) and the same NCs doped with 2 interstitial Cu atoms show good agreement to experiment. Such calculations provide valuable data to explain the changes in optical transitions due to the Cu dopant in terms of transition energies, quantum yield and dopant position as a function of dopants per NC. Changes in the optical properties of Si NCs induced by dopant concentration include extended excitation range and enhanced absorption coefficients, emission redshifts of up to 60 nm, and a two-fold increase in quantum yields up to 22%. The optical properties of doped NCs lead to significant bioimaging improvements illustrated by in vitro cell imaging, including redshifted excitation wavelengths away from natural autofluorescence and enhanced fluorescent signals.
量子点（QDs）中多发射通道的产生具有重要的基础研究和光电应用潜力。我们首次报道了半导体纳米晶体（NCs）中多发射通道的产生，其中发射通道的数量可以通过每个量子点的掺杂原子数量来控制。额外发射通道的产生可以用掺杂态与 NC 能级之间的相互作用来解释。未掺杂 2.3nm 硅（Si NCs）和掺杂 2 个间隙 Cu 原子的相同 NC 的密度泛函理论（DFT）计算与实验结果吻合较好。这些计算为解释由于 Cu 掺杂而导致的光学跃迁变化提供了有价值的数据，包括跃迁能量、量子产率和掺杂位置作为每个 NC 中掺杂剂数量的函数。掺杂浓度引起的 Si NCs 光学性质的变化包括扩展的激发范围和增强的吸收系数、高达 60nm 的发射红移以及高达 22%的量子产率增加两倍。掺杂 NC 的光学性质导致了体外细胞成像等生物成像的显著改善，包括远离天然自发荧光的红移激发波长和增强的荧光信号。
