Luminescent Cavity Design for High Ambient Contrast Ratio, High Efficiency Displays

A key display characteristic is its efficiency (emitted light power divided by input power). While display efficiencies are being improved through emissive (e.g., quantum dot and organic light emitting display (OLED) designs1,2, which remove the highly inefficient color filters found in traditional liquid crystal displays (LCDs)3,4, polarization filters, which block about 50% of the light, remain required to inhibit ambient light reflection. We introduce a luminescent cavity design to replace both the color and polarization filters. Narrow-band, large Stokes shift, CdSe/CdS quantum dot emitters are embedded in a reflective cavity pixel element with a small top aperture. The remainder of the top surface is coated black reducing ambient light reflection. A single pixel demonstrates an extraction efficiency of 40.9% from a cavity with an 11% aperture opening. A simple proof-of-concept multi-pixel array is demonstrated.

Measurement report: Particle-size-dependent fluorescence properties of water-soluble organic compounds (WSOCs) and their atmospheric implications for the aging of WSOCs

Water-soluble organic compounds (WSOCs) play important roles in atmospheric particle formation, migration, and transformation processes. Size-segregated atmospheric particles were collected in a rural area of Beijing. Three-dimensional fluorescence spectroscopy was used to investigate the optical properties of WSOCs as a means of inferring information about their atmospheric sources. Sophisticated analysis on fluorescence data was performed to characteristically estimate the connections among particles of different sizes. WSOC concentrations and the average fluorescence intensity (AFI) showed a monomodal distribution in winter and a bimodal distribution in summer, with the dominant mode in the 0.26–0.44 µm size range in both seasons. The excitation–emission matrix (EEM) spectra of WSOCs varied with particle size, likely due to changing sources and/or the chemical transformation of organics. Size distributions of the fluorescence regional integration (regions III and V) and humification index (HIX) indicate that the humification degree or aromaticity of WSOCs was the highest in the particle size range of 0.26–0.44 µm. The Stokes shift (SS) and the harmonic mean of the excitation and emission wavelengths (WH) reflected that π-conjugated systems were high in the same particle size range. The parallel factor analysis (PARAFAC) results showed that humic-like substances were abundant in fine particles (< 1 µm) and peaked at 0.26–0.44 µm. All evidence supported the fact that the humification degree of WSOCs increased with particle size in the submicron mode (< 0.44 µm) and then decreased gradually with particle size, which implied that the condensation of organics occurred in submicron particles, resulting in the highest degree of humification in the particle size range of 0.26–0.44 µm rather than in the < 0.26 µm range. Synthetically analyzing three-dimensional fluorescence data could efficiently reveal the secondary transformation processes of WSOCs.

Rational Design and Synthesis of Large Stokes Shift 2,6-Sulphur-Disubstituted BODIPYs for Cell Imaging

Five new disubstituted 2,6-thioaryl-BODIPY dyes were synthesized via selective aromatic electrophilic substitution from commercially available thiophenols. The analysis of the photophysical properties via absorption and emission spectroscopy showed unusually large Stokes shifts for BODIPY fluorophores (70–100 nm), which makes them suitable probes for bioimaging. Selected compounds were evaluated for labelling primary immune cells as well as different cancer cell lines using confocal fluorescence microscopy.

mBeRFP, a versatile fluorescent tool to enhance multichannel live imaging and its applications

Cell and developmental biology increasingly require live imaging of protein dynamics in cells, tissues or living organisms. Thanks to the discovery and the development of a panel of fluorescent proteins over the last decades, live imaging has become a powerful and commonly used approach. However, multicolor live imaging remains challenging. The generation of long Stokes shift red fluorescent proteins, such as mBeRFP, offers interesting new perspectives to bypass this limitation. Here, we constructed a set of mBeRFP-expressing vectors and provided a detailed characterization of this fluorescent protein for in vivo live imaging and its applications in Drosophila. Briefly, we showed that a single illumination source is sufficient to simultaneously stimulate mBeRFP and GFP. We demonstrated that mBeRFP can be easily combined with classical green and red fluorescent protein without any crosstalk. We also showed that the low photobleaching of mBeRFP is suitable for live imaging, and that this protein can be used for quantitative applications such as FRAP or laser ablation. Finally, we believe that this fluorescent protein, with the set of new possibilities it offers, constitutes an important tool for cell, developmental and mechano biologists in their current research.

Stable Twisted Conformation Aza-BODIPY NIR-II Fluorescent Nanoparticles with Ultra-large Stokes Shift for Imaging-Guided Phototherapy

Fluorescence imaging in the second near-infrared window (NIR-II, 1000–1700 nm) holds great promise for in vivo imaging and imaging-guided phototherapy with deep penetration and high spatiotemporal resolution. It is very...