Zongtao Li,Zongtao Li,Jiayong Qiu,Xiujuan Liu,Jiasheng Li
To address challenges in enhancing color uniformity and ambient contrast ratio (ACR) in RGB light-emitting diodes (LEDs) without losing efficiency, we developed a scattering-enhanced magnetic manipulation (SEMM) bilayer structure. The effect of the TiO2 scattering layer on improving the LED’s angular intensity non-uniformity (AIN) was studied by ray-tracing simulations and optimized by varying the particle concentration. The magnetic manipulation technique formed the microcolumns and magnetic chains of the Fe3O4 anti-reflective layer, which was optimized by adjusting Fe3O4 particle size, magnetic field strength, and Fe3O4 concentration. The resulting bilayered device significantly increased the ACR by 11.38 times and reduced AIN by 63% compared to conventional graphite-based LEDs, while maintaining high brightness and consistent color quality across angles. This marks a pioneering application of magnetic manipulation in enhancing LED display quality.
Luminescent solar concentrator (LSC) integrated with c-Si photovoltaic cells (PV cells) in building integrated photovoltaics (BIPV) could grow up to be an important element of our life for energy harvest in the future. Heavy metal free quantum dots (QDs) are promising for LSC applications, which can be controlled to possess effective large Stokes Shift and low reabsorption of emission that benefit their applications in BIPV. In our work, different amount and size of SiO 2 particles were added to CuInS 2 /ZnS QDs based LSCs to realize highly efficient scattering enhanced LSC (S-LSC) devices. Since SiO 2 particles induced scattering effect, we achieved a power conversion efficiencies (PCE) of 4.20%, which showed an improvement of 60.3% compared with the pure QDs based LSC without SiO 2 particles. This study suggests a new method of scattering enhancement to realize better performance for LSC.
Graphene, especially few-layer graphene solid film, has been found to strongly suppress fluorescence and enhance Raman signals of probe molecules. In this paper, we attempt to explore the possibility of using graphene nanocolloids as potential substrates for the enhancement of Raman scattering. Graphene nanocolloids chemically produced from the reduction of graphene oxide by sodium citrate are nearly all monolayers in solution and are also found to exhibit certain surface-enhanced Raman scattering (SERS) activity to common aromatic probe molecules. Interestingly, largely different from few-layer graphene solid film, graphene nanocolloids show maximal SERS activity only when the probe molecules are at resonant laser excitation. According to our analysis, this phenomenon should arise from a combined effect of fluorescence quenching of graphene and a photoinduced charge transfer mechanism, in which the strong charge transfer accounts for the main contribution from close coupling between graphenes and probe molecules photoinduced by resonant excitation as well as the desolvation of graphene sheets and probe molecules.
Jinhu Wang,Yinhua Yang,Hua Li,Jun Gao,Ping He,Liang Bian,Faqin Dong,Yi He
Preparation of color-tunable and stable plasmonic MoO3 nanomaterials remains challenging, due to the lack of an effective preparation strategy and surface protection in heavily doped MoO3. Herein, we report a facile and reliable method for synthesis of oxygen-deficient MoO3 (MoO3−x) nanosheets using dopamine as the reducing agent and precursor for the formation of a polydopamine (PDA) surface coating. The PDA-coated MoO3−x nanosheets show stable and tunable localized surface plasmon resonance (LSPR) from the ultraviolet to the near-infrared region (361–809 nm) via altering the pH value of the medium, accompanying the generation of multicolor nanosheet dispersions, such as deep blue, faint bluish, orange, yellow and black. Importantly, the resulting PDA-coated MoO3−x nanosheets are quite stable even in the presence of oxidants, and they can be used as an ultrasensitive surface-enhanced Raman scattering (SERS) substrate. The limit of detection for rhodamine 6G (R6G) dye is down to 0.3 fM concentration, and the corresponding Raman enhancement factor reaches 1 × 1010. The coupling of charge transfer between R6G and PDA-coated MoO3−x nanosheets and molecular resonances may be responsible for the strong SERS effect.
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