class of solar absorber material. These halide perovskite materials have been known since 1970s, and their optical and electrical properties had been investigated by several groups. [1][2][3][4][5][6] Toward their application in solar cells, Kojima et al. first employed CH 3 NH 3 PbI 3 and CH 3 NH 3 PbBr 3 as the light absorber using dye-sensitized solar cell configuration. [7] M. Grätzel and co-workers reported the first all-solid-state perovskite-based mesoscopic solar cells. [8] These class of perovskites material offers unique opto-electronic traits namely ambipolar charge transport, high absorption coefficient, and long electron/hole diffusion length, making them highly desired for PV application. Moreover, the ease of synthesis and low temperature crystallization makes them a good choice for low cost PV devices with high efficiencies. Being aware of these aforementioned remarkable optoelectronic properties and solution processability of halide perovskites, perovskite solar cells (PSCs) have attracted immense research attention worldwide. [9][10][11][12][13][14] They demonstrate a certified PCE of 25.5%, which is higher than that of organic solar cells and most of inorganic solar cells such as multi-crystalline silicon and copper indium gallium diselenide based solar cells. [15] In addition to their application in solar cells, owing to their intrinsic properties the halide perovskites have been employed in a wide range of optoelectronic devices, such as light-emitting diode (LED), lasers, photodetectors, and Perovskite solar cells (PSCs) have achieved certified power conversion efficiency (PCE) over 25%. Though their high PCE can be achieved by optimizing absorber layer and device interfaces, the intrinsic instability of perovskite materials is still a key issue to be resolved. Mixed-halide perovskites using multiple halogen constituents have been proved to improve robustness; however, the anion at the X site in the ABX 3 formula is not limited to halogens. Other negative monovalent ions with similar properties to halogens, such as pseudo-halogens, have the opportunity to form perovskites with ABX 3 stoichiometry. Recently, thiocyanates and formates have been utilized to synthesize stable perovskite materials. This review presents the evolution of pseudo-halide perovskite solar cells in the past few years. The intrinsic properties, their effects on crystal structure, and bandgap engineering of the pseudo-halide perovskites are summarized. Various thiocyanate compounds applied in the fabrication of perovskite solar cells are discussed. The fabrication process, film formation mechanism, and crystallinity of pseudo-halide perovskites are elucidated to understand their effects on the photovoltaic performance and device stability. Other applications of pseudo-halide perovskites are summarized in the final section. Lastly, this review concludes with suggestions and outlooks for further research directions.

The present study explores the features of tetragonally stabilized polycrystalline zirconia nanophosphors prepared by a sonochemistry based synthesis from zirconium oxalate precursor complex. The sonochemically prepared pristine zirconia, 3 mol%, 5 mol% and 8 mol% yttrium doped zirconia nanophosphors were characterized using thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The reaction mechanism of formation of zirconia nanophosphors is discussed in detail. The probable sonochemical formation mechanism is being proposed. Stabilization of tetragonal phase of pristine zirconia even at room temperature was effectively established by controlling the particle size using ultrasonic waves. Improved phase purity and good surface morphology of the nanophosphors is being achieved via sonochemical route. FE-SEM micrographs reveal that the nanoparticles have uniform spherical shape and size. The narrow particle size distribution (∼15-25 nm) of the zirconia nanoparticles was found from FE-SEM statistical analysis and further confirmed by TEM. Zirconia nanophosphors exhibit a wide energy band gap and which was found to vary with yttrium dopant concentration. The highlight of the present study is the synthesis of novel nanocrystalline ZrO₂ and Y-ZrO₂ phosphor which simultaneously emits extremely sharp as well as intense UV, violet and cyan light on exciting the host atom. The yttrium ion dopant further enhances the photoluminescence property of zirconia. These nanocrystalline phosphors are likely to have remarkable optical applications as light emitting UV-LEDs, UV lasers and multi color displays.

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Herein, the aspects of ion migration in polycrystalline CH3NH3PbBr3 thin film and their phenomenal influences on the output performance of perovskite light‐emitting diodes (PeLEDs) are reported. The physical insight of bias‐induced migration of mobile ions in the perovskite active layer effectuating the observed non‐linearity in the increased magnitude of electroluminescence (EL) and luminous efficiency (LE) as a function of current density for PeLEDs is directly evidenced using the capacitance spectroscopy. Adding the zwitterion molecule, Choline chloride (Ch.Cl), in CH3NH3PbBr3 precursor solution for preparing polycrystalline perovskite film effectively passivates the charged defects, either positively or negatively, in organic‐inorganic halide perovskite and most importantly interferes the migration of ions crossing the grains in PeLEDs as verified by the higher calculated magnitude of the activation energy for the migration of mobile ions. As a result, the Ch.Cl‐additive devices exhibit the rather stable EL and LE magnitude under the electric bias. EL magnitude increases linearly as a function of current density, revealing the epitome of output characteristics for decent light‐emitting diodes. To suppress the influence of the migrating ions on operating PeLEDs is a key issue before it is stepped further to advance the efficiencies and the operational stabilities of perovskite devices.

Here we report the effect of microwave treatment on a silica-carbon (SiO 2 /C) filler derived from rice husk and the function of the microwave-treated filler in an epoxy matrix for electronic packaging applications. Thermogravimetric analysis revealed improved thermal stability of the SiO 2 /C filler upon microwave treatment. X-ray diffraction analysis indicated partial SiC formation after the microwave treatment. For packaging applications, compared to that of the pure epoxy polymer, the thermal conductivity of the epoxy-SiO 2 /C composite was improved by 178% at 40 wt % content of the microwave-treated SiO 2 /C filler. Furthermore, an improvement of 149% in storage modulus and 17.6 C in glass transition temperature of the epoxy-SiO 2 /C composites was realized. The improvement in thermal stability of SiO 2 /C filler could be achieved via a simple microwave treatment, which in turn enhanced the thermal stability, thermal conduction, and thermomechanical strength of the electronic packaging materials.