Efficient Full-Color Boron Nitride Quantum Dots for Thermostable Flexible Displays.

Hexagonal boron nitride quantum dot (BNQD) has aroused great interest in the optoelectronics field due to their metal-free nature with promising optical properties. However, it has been a great challenge to modulate its photoluminescence to the long-wavelength region so far. Herein, BNQDs with full-color emission (420-610 nm) have been implemented by doping diverse amino ligands in different solvents for the first attempt. This color variation from blue, green, yellow-green, yellow to red is ascribed to the surface states tunable via amination degree. Attractively, the quantum yield of our blue BNQDs has set a record at 32.27%, and rare yellow-green BNQDs have been demonstrated. Combining good thermal dissipation capability and high transparency, our full-color BNQD holds great potential for transparent flexible display and security labels at the elevated temperature.

Vesicle formation induced by metal ions from micelle-forming sodium hexadecylimino diacetate in dilute aqueous solution.

In dilute aqueous solution, micelle-forming sodium hexadecylimino diacetate assembles into vesicles induced by Cu(II), Co(II) and Ni(II) ions.

Strong blue-fluorescence-emitted stable monolayers formed in organic solvents by a coordination polymer with long-chained bis-Schiff base.

The coordination polymer, P(ZnL) (L=N,N'-bis[2-hydroxy-4-(dodecyloxy)benzaldehyde)]-ethylenedimine), forms a novel uniform lamellar superstructure in organic liquids, which exhibits intense fluorescence in organic dispersions as well as in the corresponding cast films.

Fourier transform surface-enhanced Raman scattering of single-layer nucleolipid Langmuir-Blodgett films on silver island film substrates.

Surface-enhanced Raman scattering (SERS) spectra of four amphiphilic nucleolipids in single-layer Langmuir-Blodgett (LB) films deposited on silver island film substrates from pure water and complementary nucleotide-containing subphase and corresponding powder normal Raman spectra were obtained. The analysis of these spectra indicates that the SERS effect is mainly caused by a charge-transfer mechanism, and only the nucleobase headgroup moieties and complementary bases combined with them through hydrogen bonds, which are directly in contact with the silver island film substrates, could be enhanced. For the amphiphilic nucleolipids with the identical nucleobase headgroups, the SERS spectra of the LB films are similar, implying that the orientations of these nucleobase moieties on the silver substrates are analogous. However, the nucleobase takes different orientations on the silver substrates before and after complementary binding. The nucleobases in the LB films deposited from pure water are nearly lying flat on the silver surface, while the complementary binding pairs transferred from the air/water interface tend to take an end-on orientation on the metal surface.

Organization and properties of a conjugated poly(heteroarylene methines) at the air-water interface and in the Langmuir-Blodgett films.

A poly(heteroarylene methine) derivative, poly[(2,5-thiophenediyl) (p-n-methyl, n-octylaminobenzylidene) (2,5-thiophenequinodimethaneiyl)] (PTABQ), has been synthesized and spread at the air-water interface. The influences of three kinds of solutions on PTABQ monolayer behavior at the air-water interface have been investigated via the measurements of the pi-A isotherm and film stability. The results show that all three kinds of PTABQ solutions are apt to form the stable and transferable monolayer film organized with the plane of its pi-system nearly perpendicular to the air-water interface. Moreover, the monolayer-forming ability of PTABQ can be improved by introducing a water-soluble amphiphilie as an extractable spread-aiding component, which is further proved by the AFM images and FTIR spectra of the transferred films. UV-visible absorption spectra indicate that the well-ordered layer-by-layer structure is successfully controlled in the LB films. The optical bandgap of PTABQ is reduced for the ordered arrangement of its molecules in LB films. The intrinsic electrical conductivity of PTABQ LB films is 8.1 x 10(-8) S/cm and the conductivity of iodine-doped films is 5.7 x 10(-7) S/cm.

LB film structure of poly(2-methoxy,5-(8-methoxy-3,6-dioxa-1-undecoxy)-p-phenylene vinylene) studied by spectroscopy.

A PPV derivative, poly(2-methoxy,5-(8-methoxy-3,6-dioxa-1-undecoxy)-p-phenylene vinylene), has been synthesized by the Gilch route to study the influence of a long alkyl side chain and a di(ethylene oxide) methyl ether group on the multilayer structure obtained by Langmuir-Blodgett (LB) technique. UV-visible, PL, and FTIR spectra are applied to study the conformation and orientation of the MMDU-PPV molecules in multilayer organization. MMDU-PPV is apt to form a transferable monolayer film, in which the plane of its pi system is perpendicular to the air-water interface. The adjacent conjugated main chains of MMDU-PPV in LB films are aligned in parallel fashion and packed with the plane of its pi system approximately perpendicular to the layer plane and not organized to compact pi-stacking structure for introducing di(ethylene oxide) methyl ether (DEOM) side chains to conjugated main chains. The long alkyl side chains are characterized by all trans-zigzag conformation and average tilt angle of 36+/-1.5 degrees. The layer-by-layer multilayer of MMDU-PPV obtained by Langmuir-Blodgett technique exhibits some in-plane anisotropy and more pure photoluminescence than that of the dilute MMDU-PPV solution.

Fourier transform infrared spectroscopy study on order-disorder transition in Langmuir-Blodgett films of 7-(2-octadecyloxycarbonylethyl)guanine before and after recognition to cytidine.

Order-disorder transitions of 9-monolayer Langmuir-Blodgett (LB) films of 7-(2-octadecyloxycarbonylethyl)guanine (ODCG) before and after recognition to cytidine were investigated by Fourier transform infrared (FTIR) spectroscopy. The different order-disorder transitions suggest that molecular recognition between ODCG and cytidine influence these two LB films on the order-disorder process of alkyl tailchain. Cleavage of the multi-hydrogen bonds was also observed by the infrared spectroscopy at elevated temperature.