Synergistic Approach toward Erbium-Passivated Triple-Anion Organic-Free Perovskite Solar Cells with Excellent Performance for Agrivoltaics Application.

All-inorganic perovskite solar cells (IPSCs) have gained massive attention due to their less instability against common degradation factors (light, heat, and moisture) than their organic-inorganic hybrid counterparts. Inorganic perovskites bear a general formula of CsPbX3 (X = Cl, I, Br). The mixed halide CsPbIBr2 perovskite possesses an intermediate band gap of 2.03 eV with enhanced stability, which is still available for photovoltaic applications and the research focus of this work. We present a synergistic approach of pre-heated solution dropping with inorganic additive inclusion to deposit the organic-free triple anion CsPbIBr2 PSC. Erbium (Er)-passivated triple-anion CsI(PbBr2)0.97(ErCl3)0.03 IPSCs with inorganic carrier selective layers (CTLs), that is, organic-free, are fabricated with enhanced carrier diffusion length and crystalline grain size while lessening the grain boundaries near perovskite active layer (PAL)-bulk/carrier selective interfaces. As a result, the trap-state densities within the perovskite bulk were suppressed with stabilized CTL/PAL interfaces for smooth and enhanced carrier transportation. Therefore, for the first time, we contradict the common belief of VOC loss due to halide segregation, as a nice VOC of about 1.34 V is achieved for an organic-free IPSC through enriching initial radiative efficiency, even when halide segregation is present. The optimized organic-free IPSC yielded a power conversion efficiency of 11.61% and a stabilized power output of 10.72%, which provides the potential opportunity to integrate into agrivoltaics (AgV) projects.

Design and experimental analysis of dual-band polarization converting metasurface for microwave applications.

The manipulation of polarization state of electromagnetic waves is of great importance in many practical applications. In this paper, the reflection characteristics of a thin and dual-band metasurface are examined in the microwave frequency regime. The metasurface consists of a 22 × 22 element array of periodic unit cells. The geometry of the unit cell consists of three layers, including a 45° inclined dipole shape metal patch on top, which is backed by a 1.6 mm thick FR-4 substrate in the middle, and a fully reflective metallic mirror at the bottom. The proposed surface is exposed to horizontally (x) or vertically (y) polarized plane waves and the co and cross polarization reflection coefficients of the reflected waves are investigated experimentally in the 6-26 GHz frequency range. The metasurface is designed to convert incident waves of known polarization state (horizontal or vertical) to orthogonal polarization state (vertical and horizontal) in two distinct frequency bands, i.e. 7.1-8 GHz and 13.3-25.8 GHz. In these two frequency bands the simulated and experimental results are in good agreement. The polarization conversion ratio (PCR) of the surface is greater than 95% in the targeted frequency bands. A detailed parametric analysis of the metasurface is also discussed in this work and it has been estimated that the surface has the additional ability to convert linearly polarized waves to circularly polarized waves at several distinct frequencies. The proposed metasurface can be utilized in sensor applications, stealth technology, electromagnetic measurements, and antennas design.

Electronic and nanostructure engineering of bifunctional MoS2 towards exceptional visible-light photocatalytic CO2 reduction and pollutant degradation.

With recently increasing environmental issues and foreseeable energy crisis, it is desirable to design cheap, efficient, and visible-light responsive nano-photocatalyst for CO2 conversion and pollutant degradation. Herein, we report a flower-like of MoS2-based hybrid photocatalyst with high efficiency through nanostructure and electronic structure engineering. Nanostructure control is used to fabricate MoS2 in to flower-like nanosheets (NSs) with large surface active area. Then MoS2 is coupled with conduction-band edge matched tin dioxide (SnO2) and decorated with Ag nanoparticles for suitable work function to create a unique cascade band alignment electronic structure to facilitate photoexcited charge transfer. It is shown that the amount-optimized nanocomposite of SnO2/Ag/MoS2 exhibits exceptional visible-light photocatalytic activities for conversion of carbon dioxide (CO2) to methane (CH4), approximately one order of magnitude enhancement than original MoS2 with the apparent quantum efficiency 2.38% at 420 nm. Similarly, the optimized sample also shows high activities for 2,4-diclorophenol, Methylene-Blue, Rhodamine-B and Methyl-Orange degradation as compared to pure MoS2. It is clearly demonstrated through combination of hydroxyl radical evaluation, photoelectrochemical and electrochemical impedance, that the enhanced photoactivities are attributed to the increased specific surface area, optimized band alignment for charge transfer and suppressed recombination. Our current work provides feasible routes for further research.