Very recently, the NHCH  =  NHPbI (FAPbI) perovskite material has attracted considerable attention in fabricating solar cells (SCs). For a photovoltaic material, its refractive index and extinction coefficient, n(λ) and k(λ), as functions of λ, are important to study its optical properties and to estimate the power conversion efficiency potential for the SCs made of it. As far as we know, to date there has been no reports of n(λ) and k(λ) for FAPbI material. In this article, with spectroscopic ellipsometry (SE) measurements, the n(λ) and k(λ), as well as E =  1.45 eV for FAPbI, are acquired. The fast deposition crystallization (FDC) procedure combined with the slowed down annealing (SDA) process is applied to fabricate smooth and uniform FAPbI film on quartz substrate. Several kinds of organic solvents were tried as the second solvent in the FDC procedure, and it is found that when petroleum ether is used, the smallest surface roughness and good FAPbI material purity of the FAPbI film can be acquired. The k(λ) results for FAPbI obtained by SE, calculated from the n(λ) using the Kramers-Kronig relationship, by absorbance, and by first-principles calculations, are compared. The n(λ) and k(λ) for FAPbI are also compared with those for CHNHPbI, GaAs and c-Si.

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Organic-inorganic halide perovskite CH3NH3PbX3 (X= I, Br, Cl) quantum dots (QDs) possess the characters of easy solution-process, high luminescence yield, and unique size-dependent optical properties. In this work, we have improved the nonaqueous emulsion method to synthesize halide perovskite CH3NH3PbBr3 QDs with tunable sizes. Their sizes have been tailored from 5.29 to 2.81 nm in diameter simply by varying the additive amount of surfactant, n-octylamine from 5 to 120 μL. Correspondingly, the photoluminescence (PL) peaks shift markedly from 520 nm to very deep blue, 436 nm due to quantum confinement effect. The PL quantum yields exceed 90% except for the smallest QDs. These high-quality QDs have potential to build high-performance optoelectronic devices.

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It is demonstrated that Mg, Cr, Mn and B can be doped close to GaAs surface by plasma doping without external bias at room temperature (RT). The process only takes a few minutes, and impurity densities in the range of 1018–1021/cm3 can be achieved with doping depths about twenty nanometers. The experiment results are analyzed and the physical mechanism is tentatively explained as follows: during the doping process, impurity ion implantation under plasma sheath voltage takes place, simultaneously, plasma stimulates RT diffusion of impurity atom, which plays the main role in the doping process. The enhanced RT diffusion coefficients of Mg, Cr, Mn and B in GaAs are all in the order of magnitude of 10-15 cm2sec-1. This is reported for the first time among all kinds of plasma assisted doping methods.

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Ultrahigh molecular weight polyethylene (UHMWPE) fiber is a high-performance material with superior properties of high strength and modulus, low density, wear resistance and corrosion resistance. But the development of UHMWPE fiber reinforced polymers is hindered due to its inert inactive surface and poor interfacial adhesion with polymer matrix. This work presents the research progress on surface modification techniques, including ‘dry’ treatment, strong oxidant treatment, chemical grafting and coating, of UHMWPE fiber and the mechanisms of the improvement on surface properties and interfacial adhesion strength between the UHMWPE fiber and the polymer matrix. Application status of UHMWPE fiber such as aerospace, ocean engineering and individual protection is introduced.