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In order to investigate the reflected beam shifts in the anisotropic chiral metamaterial based on the Ωparticle resonance model, we give the expression of the Goos-H?nchen(GH) shifts of reflected beam by using the stationary phase method. The numerical results show that for the incidence of the transverse magnetic wave, the relative GH shifts of co-polarization reflection are enhanced at two Brewster angles, and the enhancement peak of GH shift is larger corresponding to the large Brewster angle. Meanwhile, the enhancement of GH shifts at large Brewster angle is very sensitive to the thickness of the chiral material and incident frequency, the transition of the positive and negative enhancement of the GH shift can be realized by slightly adjusting the thickness or incident frequency. As the incident angle is fixed, the positive and negative transition of the co-polarization GH shifts at different thicknesses can be realized by selecting the appropriate incident frequency. In addition, for the fixed thickness of chiral materials, the positive and negative enhancement of the co-polarization GH shifts at different frequencies can be achieved by modifying the incident angles slightly.

Despite the recent rapid development in the organic–inorganic halide perovskite solar cells (PSCs), the crystalline stability of the perovskite (PVK) material, particularly of the MAPbI3, remains a significant impediment to PSC applications. We proposed that short-term ultraviolet (UV) irradiation under air conditions can stabilize the PVK phase and increases the film crystallinity. Detailed investigations indicated that the electrons can be released from the bridging hydroxyls (OHB) bonds under UV irradiation to generate a small amount of active oxygen (O2−) on the TiO2 film surface, forming stable Pb–O bonds and α phase PVK. A 25% increases in photovoltaic conversion efficiency with a considerable stability, and the device maintains over 90% efficiency after 400 h of storage in N2. This study provides a simple and effective method to produce efficient and stable PSC devices at low cost. [ABSTRACT FROM AUTHOR]

Different concentrations of NH4Cl are introduced to MAPbI3 precursor solution, planar MAPbI3 perovskite films, and solar cells' performance with or without NH4Cl have been studied. The NH4Cl/MAPbI3 films exhibit increased grain size and narrowed grain boundaries. The light absorption of perovskite films with different concentrations of NH4Cl was also evaluated. To understand the growth of perovskite films with NH4Cl added to perovskite precursor solutions, XRD and XPS spectroscopy were conducted on different perovskite film samples. By adding NH4Cl, the MAPbI3 film shows good crystal quality and the shift of Pb peaks indicates that NH4Cl is not physically mixed but chemically incorporated into MAPbI3 films. We attribute the effect to Cl ions of NH4Cl combining with free lead ions of MAPbI3 so as to fill the vacancy of volatile I ions in the NH4Cl–MAPbI3 films. The 20 mg NH4Cl-based device showed an enhanced performance of a PCE of 13.67% compared to the device without adding NH4Cl with a PCE of 10.24%. The introduction of 20 mg NH4Cl achieved the best passivation effect. Using a 20 mg NH4Cl device, the trap density can be reduced to 0.84 × 1016 cm−3, resulting in more efficient charge removal from the surface and improved performance. [ABSTRACT FROM AUTHOR]