Wang Zhongxiang, Schnable David, Fan Qingsong, Li Zhiwei, Ung Gaël, Yin Yadong
Department of Chemistry, University of California, Riverside, California 92521, United States.
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States.
ACS Nano. 2024 Feb 13;18(6):5122-5131. doi: 10.1021/acsnano.3c12344. Epub 2024 Feb 1.
Colloidal assembly has emerged as an effective avenue for achieving polarized light emission. Here, we showcase the efficacy and versatility of the magnetic colloidal assembly in enabling both linearly and circularly polarized luminescence. Colloidal europium-doped NaYF nanorods with surface-bound FeO nanoparticles are magnetically assembled into linear or chiral superstructures using corresponding fields created in permanent magnets. In a uniform magnetic field generated by opposing poles, the assemblies exhibit photoluminescence with intensity tunable in response to the magnetic field direction, which is higher when the nanorods are perpendicular to light propagation than when they are parallel. The obtained superstructures display strong linearly polarized luminescence when the nanorods are aligned vertically, exhibiting a high degree of polarization up to 0.61. In a quadrupole chiral field generated by permanent magnets, the assemblies emit left-handed or right-handed polarized light depending on the position of the sample placement, attaining a -factor of 0.04. Furthermore, the superstructures immobilized in a hydrogel film are found to retain their chirality, exhibiting opposite chiroptical responses depending on the sample orientation. The magnetic colloidal assembly approach facilitates the convenient and efficient generation of polarized light emissions from nonmagnetic luminescent materials, thus creating opportunities for tailoring light behavior in developing innovative optoelectronic devices.
胶体组装已成为实现偏振光发射的有效途径。在此，我们展示了磁性胶体组装在实现线性和圆偏振发光方面的功效和多功能性。表面结合有FeO纳米颗粒的胶体铕掺杂NaYF纳米棒，利用永磁体产生的相应磁场被磁性组装成线性或手性超结构。在由相对磁极产生的均匀磁场中，组件表现出光致发光，其强度可根据磁场方向进行调节，当纳米棒垂直于光传播方向时的强度高于平行时的强度。当纳米棒垂直排列时，所获得的超结构显示出强烈的线性偏振发光，偏振度高达0.61。在由永磁体产生的四极手性场中，组件根据样品放置位置发射左旋或右旋偏振光，获得的g因子为0.04。此外，固定在水凝胶膜中的超结构被发现保留了它们的手性，根据样品取向表现出相反的手性光学响应。磁性胶体组装方法有助于从非磁性发光材料方便、高效地产生偏振光发射，从而为开发创新光电器件时定制光行为创造机会。
