Rui Xia

Precision excimer laser annealed Ga-doped ZnO electron transport layers for perovskite solar cells

Organic–inorganic hybrid perovskite solar cells (PSCs) continue to attract considerable attention due to their excellent photovoltaic performance and low cost. In order to realize the fabrication of PSCs on temperature-sensitive substrates, low-temperature processing of all the components in the device is required, however, the majority of the high-performance PSCs rely on the electron transport layers (ETLs) processed at high temperatures. Herein, we apply excimer laser annealing (ELA) to treat ETLs (Ga-doped ZnO, GZO) at room temperature. A synergetic improvement in optical transparency and electrical conductivity is achieved after ELA treatment, which in turn improves light absorption, enhances electron injection, and depresses charge recombination. Devices fabricated with ELA treated GZO ETL acheived a power conversion efficiency (PCE) of 13.68%, higher than that of the PSCs utilizing GZO with conventional high-temperature annealing (12.96%). Thus, ELA is a promising technique for annealing ETLs at room temperature to produce efficient PSCs on both rigid and flexible substrates.

Insightful understanding of the correlations of the microstructure and catalytic performances of Pd@chitosan membrane catalysts studied by positron annihilation spectroscopy

In this study, the catalytic performances of palladium supported on chitosan (Pd@CS) membrane heterogeneous catalysts have been studied from the aspects of free volume by positron annihilation lifetime spectroscopy (PALS). The results showed that the variation in free volume hole size of the Pd@CS membrane catalyst was closely associated with microstructure evolutions, such as increase of Pd content, valence transition of Pd by reduction treatment, solvent swelling, physical aging during catalyst recycling, and so on. The PALS results showed that both the mean free volume hole size of the Pd0@CS membrane in the dry or swollen state (analyzed by the LT program) and its distribution (analyzed by the MELT program) are smaller than the molecule size of the reactants and products in the catalysis reaction. However, the results showed that the Pd0@CS membrane catalyst has excellent catalytic activity for the Heck coupling reaction of all the reactants with different molecule size. It was revealed that the molecule transport channels of the Pd0@CS membrane catalyst in the reaction at high temperature was through a number of instantaneously connected free volume holes rather than a single free volume hole. This hypothesis was powerfully supported by the catalytic activity assessment results of the CS layer sealed Pd0@CS membrane catalyst. Meanwhile, it was confirmed that the leaching of Pd0 nanoparticles of the reused Pd0@CS membrane catalyst during the recycling process was also through such instantaneously connected free volume holes.

Magnetic field aligned orderly arrangement of Fe3O4 nanoparticles in CS/PVA/Fe3O4 membranes

The CS/PVA/Fe3O4 nanocomposite membranes with chainlike arrangement of Fe3O4 nanoparticles are prepared by a magnetic-field-assisted solution casting method. The aim of this work is to investigate the relationship between the microstructure of the magnetic anisotropic CS/PVA/Fe3O4 membrane and the evolved macroscopic physicochemical property. With the same doping content, the relative crystallinity of CS/PVA/Fe3O4-M is lower than that of CS/PVA/Fe3O4. The Fourier transform infrared spectroscopy (FT-TR) measurements indicate that there is no chemical bonding between polymer molecule and Fe3O4 nanoparticle. The Fe3O4 nanoparticles in CS/PVA/Fe3O4 and CS/PVA/Fe3O4-M are wrapped by the chains of CS/PVA, which is also confirmed by scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis. The saturation magnetization value of CS/PVA/Fe3O4-M obviously increases compared with that of non-magnetic aligned membrane, meanwhile the transmittance decreases in the UV-visible region. The o-Ps lifetime distribution provides information about the free-volume nanoholes present in the amorphous region. It is suggested that the microstructure of CS/PVA/Fe3O4 membrane can be modified in its curing process under a magnetic field, which could affect the magnetic properties and the transmittance of nanocomposite membrane. In brief, a full understanding of the relationship between the microstructure and the macroscopic property of CS/PVA/Fe3O4 nanocomposite plays a vital role in exploring and designing the novel multifunctional materials.