In this work, tunable terahertz photonic crystals (PCs) used as modularized and switchable components in flexible passive device are designed and prepared. Flexible woodpile structures created by the direct-writing technology with a composite ink system composed of barium strontium titanate nanoparticles and polydimethylsiloxane are immersed in 5CB liquid crystals (LCs), where the orientation of LC molecule is modulated by the external magnetic field. Each of these can work in terahertz wavelength with specific position and depth of the dips in the transmittance spectra due to different geometries as well as having the ability of fine-tuning. Experiments show that the photonic gaps of these PCs can cover from 0.2 to 0.3 THz, as well as about 7.5% fine tunability of photonic gap appearing with the orientation change of the magnetic field. More interestingly, the dips of photonic gaps keep the same position but become deeper with the increase of layer, an ability to realize another dimensional switchover. This work demonstrates that efficient terahertz PCs with different geometry parameters could be dynamically tuned by the orientation of magnetic field and it can open a universal approach to shrinking the size of device and rapid manufacturing in a large throughput.
Full-color visible emissions are particularly crucial for applications in displays and lightings. In this work, we developed a facile room-temperature ligand-assisted supersaturated recrystallization synthesis of monodisperse, cubic structure Cs1–mFAmPbX3 (X = Cl, Br, and I or their mixtures Cl/Br and Br/I, 0 ≤ m ≤ 1) hybrid perovskite quantum dots (QDs). Impressively, cation substitution of Cs+ by FA+ was beneficial in finely tuning the band gap and in exciton recombination kinetics, improving the structural stability, and raising the absolute quantum yields up to 85%. With further assistance of anion replacement, full-spectral visible emissions in the wavelength range of 450–750 nm; narrow full width at half-maxima, and a wide color gamut, encompassing 130% of National Television System Committee television color standard, were achieved. Finally, Cs1–mFAmPbX3-polymer films retaining multicolor luminescence are prepared and a prototype white light-emitting diode device was constructed using green Cs0.1FA0.9PbBr3 and red Cs0.1FA0.9Br1.5I1.5 QDs as color converters, certainly suggesting their potential applications in the optoelectronics field.
危险品化学品经营许可证（带存储）