Colloidal CsPbX 3 (X = Br, Cl, and I) perovskite nanocrystals exhibit tunable bandgaps over the entire visible spectrum and high photoluminescence quantum yields in the green and red regions. However, the lack of highly efficient blue-emitting perovskite nanocrystals limits their development for optoelectronic applications. Herein, neodymium (III) (Nd 3+) doped CsPbBr 3 nanocrystals are prepared through the ligand-assisted reprecipitation method at room temperature with tunable photoemission from green to deep blue. A blue-emitting nanocrystal with a central wavelength at 459 nm, an exceptionally high photoluminescence quantum yield of 90%, and a spectral width of 19 nm is achieved. First principles calculations reveal that the increase in photoluminescence quantum yield upon doping is driven by an enhancement of the exciton binding energy due to increased electron and hole effective masses and an increase in oscillator strength due to shortening of the Pb-Br bond. Putting these results together, an all-perovskite white light-emitting diode is successfully fabricated, demonstrating that B-site composition engineering is a reliable strategy to further exploit the perovskite family for wider optoelectronic applications.

We report a method to prepare hydrophilic poly(dimethylsiloxane) (PDMS) stamps that could transfer patterns of polar molecules homogeneously in soft lithography. In this method, we demonstrated a twostep procedure by using a mixed gas of argon (Ar) and hydrogen (H2)-based microwave plasma pretreatment to activate PDMS and subsequent acrylonitrile grafting onto PDMS, generating a hydrophilic surface with cyano (-CN) group coatings. The PDMS hydrophilic surface exhibited high affinity for wetting acetonitrile, which is a conventional solvent for DNA synthesis. Acetonitrile droplets possessed contact angles as low as 17 ( 7°on the cyano (-CN) groups grafted PDMS stamps surface. The hydrophilicity was stable and could last for at least 1 month at room temperature. Attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectrum were used to characterize the surface hydrophilization. Such a hydrophilic and inert PDMS stamp showed significance for reactive multilevel fabrications in soft lithography. The possible chemical mechanism for PDMS surface grafting was discussed.

Some interesting experiment phenomena of light patterns that appear in microwave plasma have been investigated. The wavelength of surface plasmon polaritons (SPPs) at the dielectric-plasma interface as the functions of incident wave frequency and plasma density has been calculated. The comparison of the experiment results with the calculating results has been carried out. By experimentally and theoretically analyzing, the phenomena are considered to be caused by the surface wave of SPPs at the interface between Pyrex wall and plasma.