Organic Semiconducting Luminophores for Near-Infrared Afterglow,Chemiluminescence, and Bioluminescence Imaging

Optical imaging has played a pivotal role in deciphering in vivo bioinformatics but is limited by shallow penetration depth and poor imaging performance owing to interfering tissue autofluorescence induced by concurrent photoexcitation. The emergence of near-infrared (NIR) self-luminescence imaging independent of real-time irradiation has timely addressed these problems. There are two main kinds of self-luminescent agents, namely inorganic and organic luminophores. Inorganic luminophores usually suffer from long-term biotoxicity concerns resulting from potential heavy-metal ions leakage and nonbiodegradability, which hinders their further translational application. In contrast, organic luminophores, especially organic semiconducting luminophores (OSLs) with good biodegradable potential, tunable design, and outstanding optical properties, are preferred in biological applications. This review summarizes the recent progress of OSLs used in NIR afterglow, chemiluminescence, and bioluminescence imaging. Molecular manipulation and nanoengineering approaches of OSLs are discussed, with emphasis on strategies that can extend the emission wavelength from visible to NIR range and amplify luminescence signals. This review concludes with a discussion of current challenges and possible solutions of OSLs in the self-luminescence field.     

TiO_2压敏陶瓷晶粒半导化

本文主要研究 TiO_2陶瓷晶粒半导化的途径及晶粒电阻率的测试方法。实验结果表明,通过掺入Nb_2O_5施主杂质可以有效地降低晶粒电阻率,并使 TiO_2系陶瓷具有良好的压敏特性。     

非线性半导体SiC微粉及其半导体漆（带）特性试验方法的研究

本文介绍了非线性半导体 SiC 微粉及其半导体漆(带)伏安特性的测量方法,以及用微机程序计算其非线性特征参数的方法,从而为研究新型防晕结构提供了科学有效的手段。     

Structural and optical properties of AIN sputtering deposited on sapphire substrates with various orientations

AIN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing (HTTA) on the structural,optical properties as well as surface stoichiometry were comprehensively investigated.The significant narrowing of the (0002) diffraction peak to as low as 68 arcsec of AIN after HTTA implies a reduction of tilt component inside the AIN thin films,and consequently much-reduced dislocation densities.This is also supported by the appearance of E2(high) Raman peak and better Al-N stoichiometry after HTTA.Furthermore,the in-creased absorption edge after HTTA suggests a reduction of point defects acting as the absorption centers.It is concluded that HTTA is a universal post-treatment technique in improving the crystalline quality of sputtered AIN regardless of sapphire orienta-tion.     

Enhancement in crystallinity of poly(3-hexylthiophene) thin films prepared by low-temperature drop casting

Low-temperature casting of high molecular weight (HMW > 40 kDa) regioregular poly(3-hexylthiophene) (P3HT) is demonstrated to yield highly crystalline P3HT thin films with well defined and preferentially edge-on oriented [(100) contact plane] nanocrystallites on the pure and silanized Si/SiO₂ substrates. Transmission electron microscopy and X-ray diffraction provide evidence for the increase in preferential edge-on orientation of P3HT-conjugated backbone while decreasing the film preparation temperature below room temperature. The optimum growth temperature is about −12°C for the given concentration (2 mg/mL in CHCl₃). The reduced evaporation rate of the solvent results in a better selection of the thermodynamically stable orientation of nanocrystallites onto the substrate. The degree of preferential orientation and size of the crystallites can be further increased on n-octadecyltrichlorosilane-treated SiO₂ substrates as well as by annealing the films at 200°C for 1 h. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of Janus polyaniline–polyelectrolyte complex membrane via in situ confined polymerization

Polyelectrolyte complex (PEC) membranes prepared from poly(styrene sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC) were modified by crossflow polymerization of aniline (ANI). The PEC membranes were used as separators in a two-compartment setup where ANI monomer and ammonium persulfate (APS) oxidant diffused through the membranes to form polyaniline (PANI). APS and ANI having different distributions throughout the membranes, the reaction led to the asymmetric polymerization of PANI on one face of each PEC membrane thus producing Janus membranes. Due to the excess PANI content, the membrane displayed distinct asymmetric electrical conductivities on each face. Interestingly, very different ANI polymerizations were obtained when nonstoichiometric PEC membranes having different molar ratio of cationic and anionic polyelectrolytes (P⁺:P^? represents PDADMAC:PSS) were used and transport of APS was fastest through the 2:1 PEC when compared to the 1:2 PEC. In all experiments, the polymerization was most intense on the ANI side of the membranes. Also, the influence of NaCl both during PEC fabrication and during polymerization was studied and found to have some effect on the solute permeability. Results showed that a higher content of PANI was formed on PEC membranes having excess P⁺ and with no NaCl added during PEC fabrication. Although X-ray diffraction confirmed the presence of PANI on both sides of each membrane, scanning electron microscopy images demonstrated that both sides of each membrane had different PANI content deposited. Electrical conductivity measurements using a four-point probe setup also showed that the PEC–PANI exhibits asymmetric electrical property on different sides. © 2021 Society of Industrial Chemistry.     

Evaluation of four inch diameter VGF-Ge substrates used for manufacturing multi-junction solar cell

Low dislocation density Ge wafers grown by a vertical gradient freeze (VGF) method used for the fabrication of multi-junction photovoltaic cells (MJC) have been studied by a whole wafer scale measurement of the lattice parameter, X-ray rocking curves, etch pit density (EPD), impurities concentration, minority carrier lifetime and residual stress. Impurity content in the VGF-Ge wafers, including that of B, is quite low although B₂O₃ encapsulation is used in the growth process. An obvious difference exists across the whole wafer regarding the distribution of etch pit density, lattice parameter, full width at half maximum (FWHM) of the X-ray rocking curve and residual stress measured by Raman spectra. These are in contrast to a reference Ge substrate wafer grown by the Cz method. The influence of the VGF-Ge substrate on the performance of the MJC is analyzed and evaluated by a comparison of the statistical results of cell parameters.