Jutao Jiang

Moderate fabrication and characterization of the microcrystalline Sr2CuO3 glass films with effective nonlinearities

Since nonlinear optical materials used in the ultrafast all-optical switching is an important part for the modern optical technology, cuprates have been widely investigated for their specific Cu-O chain structure and intriguing optical properties. We present a new preparation method of microcrystalline Sr2CuO3 glass films on glass substrates combining spin-coating and co-sintering techniques. Then, the as-prepared samples were polished for different times to obtain microcrystalline Sr2CuO3 glass films with varying thickness. The influence of polishing time on the structure, the valence state and the nonlinear optical response were discussed, respectively. The purity of the Sr2CuO3 phase, surface morphology and the chemical composites of these synthesized glass films were given with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Importantly, optical absorption spectroscopy and Z-scan technique were used to measure linear absorption and third-order optical nonlinearity of the films. The experiments showed that third-order nonlinear susceptibility of the 140 min polished film sample with a thickness of 18 μm was up to 1.23 × 10−12 esu, indicating its potential application in the nonlinear field.

Efficient and stable white fluorescent carbon dots and CD-based glass thin-films via screen-printing technology for use in W-LEDs

White fluorescent carbon dots (WCDs) were synthesized by combining red carbon dots (RCDs) with ethanol or N-(β-aminoethyl)-γ-aminopropyl methldimethoxy silane (AEAPMS) for the first time. Interestingly, the RCDs have excitation-independent behavior while the WCDs exhibit excitation-dependent behavior. These WCDs emit bright white light with quantum yields (QYs) of 50.8% and 57.1%. Solvatochromism effects of the CDs were ascribed to the intermolecular charge transfer between the CDs and solvents. The solvents further increase the charge carrier density and induce the charge transfer. Investigation of the white fluorescence mechanism of the CDs revealed a multilevel emissive recombination channel, which might be from the distribution of diverse surface-state PL centers. Additionally, because the latter WCDs exhibit excellent optical properties and a great film-forming ability, workable white CD-based glass thin-films were constructed using facile screen-printing technology. Finally, the as-fabricated white light-emitting diodes (W-LEDs) exhibited an optimized color coordinate (CIE) of (0.33, 0.34), color rendering index (CRI) of 51 and correlated color temperature (CCT) of 6735 K. Therefore, the WCDs reveal the strong feasibility of being used for lighting and displays.