title: Carbon Nanodots with Sub-Nanosecond Spontaneous Emission Lifetime.
abstract: Compared with most mature cadmium-containing quantum dots (QDs), carbon nanodots (CNDs) are a new class of colloidal nanomaterials that exhibit unique photoluminescence (PL) properties while being nontoxic and easily manufactured using low-cost precursor materials. However, solid-state CNDs exhibit poor PL quantum yields (PL-QYs) and inefficient radiative transition, which significantly hinders their practical use in optoelectronic devices. To address this issue, plasmonic nanoantennas consisting of Au nanorods (Au-NRs) deposited on a flat Au film with inserted dielectric layers were used to enhance the spontaneous emission of solid-state CNDs with broad spectral linewidth. Using steady-state, time-resolved, and spatial-resolved PL measurements, we found that after coupling to plasmonic nanogaps (PNGs), the PL emission was significantly enhanced, accompanied by a PL lifetime shortening to the sub-nanosecond range (≈140 ps). According to the experimental data, the radiative transition is strongly accelerated and can thus overcome the metal loss, leading to a large PL enhancement. Our demonstration can pave the way to the design of eco-friendly nanoemitters with sub-nanosecond PL lifetime for promising applications in light-emitting devices.
authors.affiliation: Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Liu
authors.affiliation: Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan.
authors.forename: Tzu-Neng
authors.initials: TN
authors.lastname: Lin
authors.affiliation: Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan.
authors.forename: Li-Yun
authors.initials: LY
authors.lastname: Chang
authors.affiliation: Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan.
authors.forename: Zh-Cheng
authors.initials: ZC
authors.lastname: Jiang
authors.affiliation: Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan.
authors.forename: Ji-Lin
authors.initials: JL
authors.lastname: Shen
authors.affiliation: Physics Division, Institute of Nuclear Energy Research, Taoyuan, Taiwan.
authors.forename: Po-Wen
authors.initials: PW
authors.lastname: Chen
authors.affiliation: Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan.
authors.forename: Jyh-Shyang
authors.initials: JS
authors.lastname: Wang
authors.affiliation: Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan.
authors.forename: Chi-Tsu
authors.initials: CT
authors.lastname: Yuan
keywords: Purcell effects; carbon nano-dots; enhancement of radiative decay rates; plasmonic antennas