Haibo Fan

Two‐Inch‐Sized Perovskite CH3NH3PbX3 (X = Cl, Br, I) Crystals: Growth and Characterization

Two-inch-sized perovskite crystals, CH3 NH3 PbX3 (X=I, Br, Cl), with high crystalline quality are prepared by a solution-grown strategy. The availability of large perovskite crystals is expected to transform its broad applications in photovoltaics, optoelectronics, lasers, photodetectors, LEDs, etc., just as crystalline silicon has done in revolutionizing the modern electronics and photovoltaic industries.

One-step hydrothermal synthesis of monolayer MoS2 quantum dots for highly efficient electrocatalytic hydrogen evolution

Designing MoS2 nanocatalysts with ultrasmall size and few layers is an effective strategy to enhance their electrocatalytic activity in the hydrogen evolution reaction (HER). In this work, uniform MoS2 quantum dots (QDs) are synthesized by a novel and facile hydrothermal route. Transmission electron microscopy and atomic force microscopy measurements show that the resulting products possess a monolayer thickness with an average size of about 3.6 nm. Benefiting from the abundance of exposed catalytic edge sites, as well as the excellent intrinsic conductivity of the monolayer structure, the MoS2 QDs showed excellent catalytic activity with a low overpotential of approximately 160 mV and a small Tafel slope of 59 mV dec−1, which made it a promising HER electrocatalyst for practical applications.

Green emission in carbon doped ZnO films

The emission behavior of C-doped ZnO films, which were prepared by implantation of carbon into ZnO films, is investigated. Orange/red emission is observed for the films with the thickness of 60–100 nm. However, the film with thickness of 200 nm shows strong green emission. Further investigations by annealing bulk ZnO single crystals under different environments, i.e. Ar, Zn or C vapor, indicated that the complex defects based on Zn interstitials are responsible for the strong green emission. The existence of complex defects was confirmed by electron spin resonance (ESR) and low temperature photoluminescence (PL) measurement.

Band alignment of TiO2/FTO interface determined by X-ray photoelectron spectroscopy: Effect of annealing

The energy band alignment between pulsed-laser-deposited TiO2 and FTO was firstly characterized using high-resolution X-ray photoelectron spectroscopy. A valence band offset (VBO) of 0.61 eV and a conduction band offset (CBO) of 0.29 eV were obtained across the TiO2/FTO heterointerface. With annealing process, the VBO and CBO across the heterointerface were found to be -0.16 eV and 1.06 eV, respectively, with the alignment transforming from type-I to type-II. The difference in the band alignment is believed to be dominated by the core level down-shift of the FTO substrate, which is a result of the oxidation of Sn. Current-voltage test has verified that the band alignment has a significant effect on the current transport of the heterojunction.