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 ABX3 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 ABX3 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.
Monovalent pseudo‐halide anions share similar properties to halide anions. This review presents the evolution of pseudo‐halide perovskite solar cells in the past few years. The role of pseudo‐halides and their position and occupation in perovskite crystal, its impact on perovskite film quality, solar cell stability and photovoltaic performance, and pseudo‐halide optoelectronic devices beyond solar cells are compared comprehensively.
•Reaction mechanism for the synthesis of zirconia nanophosphors is elucidated.•Probable sonochemical formation mechanism of zirconia nanophosphors is proposed.•Narrow size distribution ∼15–25nm and ...good surface morphology is achieved.•Improved phase purity via controlling the grain growth by acoustic waves.•Sharp and intense photoluminescence emission spectra with FWHM ∼27.2meV.
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, 3mol%, 5mol% and 8mol% 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 (∼15–25nm) 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.
Stabilization of high temperature cubic phase of BaTiO3 at room temperature is established by rapid quenching of the surfactant assisted sonochemically synthesized BaTiO3 after calcination for 2h at ...800°C. The quenched BaTiO3 is stabilized to cubic phase at room temperature in contrast to the BaTiO3 obtained by normal cooling at a rate of 1°C/min, which exists in the tetragonal phase at room temperature. BaTiO3 prepared by the same synthetic procedure but two different heat treatment methods possesses almost similar morphology (i.e.) 1-dimensional nanorod structure but with different aspect ratio. Quenching prevents the low temperature phase transformation c→t from occurring by providing a narrow window of time in which the reaction is both thermodynamically favourable and kinetically accessible.
•BaTiO3 nanorods were prepared by surfactant assisted sonochemical method.•Stabilization of c-BaTiO3 at room temperature via rapid quenching technique.•Cooling rate is an important criterion for room temperature phase stabilization.
In this study, one‐pot hydrothermal synthesis of sheet‐like ZSM‐5 as a high‐performance catalyst for toluene disproportionation was carried out using binary surfactants. In the dual template, ...tetraethylammonium hydroxide was used to construct the microporous structure of ZSM‐5, and cationic surfactant (e.g., octadecyltrimethylammonium chloride (C18TMAC), hexadecyltrimethyl ammonium bromide (C16TMAB), and tetradecyltrimethylammonium bromide, (C14TMAB)) can change the growth habits of the ZSM‐5 crystals by hindering the regular stacking of zeolite layers from their longer hydrophobic chain. From the XRD pattern of the as‐synthesized samples which were hydrothermally treated for different time, it was found that a lamellar mesostructured intermediate gradually transformed into the sheet‐like ZSM‐5 during hydrothermal process. With a proper amount of cationic surfactant, the thickness of the sheet‐like ZSM‐5 could be controlled to less than 30 nm. Concerning the catalyst application, the toluene disproportionation performance over the sheet‐like ZSM‐5 is 1.5 times higher than that of the commercial ZSM‐5. The higher conversion is ascribed to the faster diffusion amount due to the sheet‐like ZSM‐5.
In this study, one‐pot hydrothermal synthesis of sheet‐like ZSM‐5 as a high‐performance catalyst for toluene disproportionation was carried out using binary surfactants.
•A carbon–silica material derived from rice husk agricultural waste is prepared.•The improved thermal stability can be achieved by deduced the ionic content.•The thermal-mechanical strength and ...thermal conducting of epoxy/BRH are improved.
The present study focused on the preparation and characterization of a bio-based carbon-silica material derived from rice husk agricultural waste and its function in epoxy matrix for electronic packaging applications. X-ray diffraction (XRD) analysis, N2 adsorption/desorption isotherms, and scanning electron microscopy were used to characterize the structure as well as morphology of the resultant carbon–silica material, namely black rice husk ash, called BRH. Thermogravimetric analysis results suggest that improved thermal stability can be achieved by reducing the ionic content of the BRH materials through the pre-acid-hydrothermal technique. The ionic content of Cl−, Na+, and K+ of the BRH sample respectively were 4.3, 9.8, and 9.0ppm after further post-hydrothermal process. In addition, the XRD diagram shows that the structure of the calcined BRH material, is in amorphous form, which is non-toxic to humans. For packaging application, an improvement of 147% in storage modulus and 49% in CTE by the addition of 46% filler was realized. In addition, compared with pure polymer, the thermal conductivity values of the epoxy/pre-BRH composites were improved by 142%. From these results, it was concluded that this BRH filler derived from waste rice husks can promote the thermal stability, thermal-mechanical strength, and thermal conduction of the Epoxy/BRH composites.
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Abstract
Herein, the aspects of ion migration in polycrystalline CH
3
NH
3
PbBr
3
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 CH
3
NH
3
PbBr
3
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.
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.
The external electric bias in operating CH3NH3PbBr3 perovskite light‐emitting diodes (PeLEDs) drives the migration of mobile ions and causes the bias‐induced enhancement of luminance. The studies clearly reveal the fundamental aspects to retard the migrating ions in operating PeLEDs, which would markedly advance the efficiencies and the operational stabilities of perovskite devices in future.
Here we report the effect of microwave treatment on a silica–carbon (SiO2
/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 SiO2
/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–SiO2
/C composite was improved by 178% at 40 wt % content of the microwave‐treated SiO2
/C filler. Furthermore, an improvement of 149% in storage modulus and 17.6°C in glass transition temperature of the epoxy–SiO2
/C composites was realized. The improvement in thermal stability of SiO2
/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.
Improvement in thermal stability of SiO2/C filler could be achieved via a microwave treatment, which in turn enhanced the thermal stability, thermal conduction, and thermomechanical strength of the electronic packaging materials.
