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A Systematical Study on Bands and Defects of CsBXsub.3 Perovskite Based on First Principles
Metal halide perovskites have attracted considerable attention as novel optoelectronic materials for their excellent optical and electrical properties. Inorganic perovskites (CsPbX[sub.3], X = Cl, Br, I) are now viable alternative candidates for third-generation photovoltaic technology because of their high photoelectric conversion efficiency, high carrier mobility, good defect tolerance, simple preparation method and many other advantages. However, the toxicity of lead is problematic for practical implementation. Thus, the fabrication of lead-free perovskite materials and devices has been actively conducted. In this work, the energy band and photoelectric properties of inorganic perovskites CsBX[sub.3] (B = Pb, Sn, Ge, X = Cl, Br, I) have been investigated with the first principles calculation, and the possible defect energy levels and their formation energies in different components, in particular, have been systematically studied. The advantages and disadvantages of Sn and Ge as replacement elements for Pb have been demonstrated from the perspective of defects. This study provides an important basis for the study of the properties and applications of lead-free perovskites.
Journal Article
Perovskite solar cells : technology and practices
\"Key features: Provides an update on a hot trending topic of renewable energy and energy conversion technologies ; Introduces emerging materials processing methods of PSCs ; Covers electron-transporting layers in PSCs, hole-transporting layers in PSCs, and lead-free PSCs ; Includes easy-to-understand diagrams and configurations ; Serves as a quick guide on PSCs for young researchers\"-- Provided by publisher.
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Performance Degradation of a Double-Perovskite PrBaCosub.2Osub.5+δ Cathode Operating under a COsub.2/Hsub.2O-Containing Atmosphere
The electrochemical activity and stability of the PBCO electrode are investigated under the annealing processes in an atmosphere containing CO[sub.2]/H[sub.2]O for solid oxide fuel cells (SOFCs). The electrochemical impedance spectrum results unequivocally confirm the significant deterioration in PBCO cathode performance upon annealing under ambient air conditions, particularly when exposed to CO[sub.2]/H[sub.2]O atmospheres. Microstructure and surface chemical state analyses reveal the segregation of BaO on the PBCO surface, and the formation of insulating BaCO[sub.3] degraded the electrochemical performance. CO[sub.2] and H[sub.2]O exhibit a significant induced effect on the segregation of Ba in PBCO to the surfaces, thereby causing a rapid decline in electrode performance. Additionally, the analysis of volume relaxation reveals that the presence of oxygen in the electrode environment can also influence the deposition process occurring on the surface of the electrode. However, this phenomenon is not observed in N[sub.2]. This study emphasizes the impact of various gases present in the working atmosphere on surface-separated BaO, which consequently plays a pivotal role in the activity and long-term stability of PBCO electrodes.
Journal Article
A Functional Biological Molecule Restores the PbIsub.2 Residue-Induced Defects in Two-Step Fabricated Perovskites
Coating the perovskite layer via a two-step method is an adaptable solution for industries compared to the anti-solvent process. But what about the impact of unreacted PbI[sub.2]? Usually, it is generated during perovskite conversion in a two-step method and considered beneficial within the grain boundaries, while also being accused of enhancing the interface defects and nonradiative recombination. Several additives are mixed in PbI[sub.2] precursors for the purpose of improving the perovskite crystallinity and hindering the Pb[sup.2+] defects. Herein, in lieu of adding additives to the PbI[sub.2], the effects of the PbI[sub.2] residue via the electron transport layer/perovskite interface modification are explored. Consequently, by introducing artemisinin decorated with hydrophobic alkyl units and a ketone group, it reduces the residual PbI[sub.2] and improves the perovskites’ crystallinity by coordinating with Pb[sup.2+]. In addition, artemisinin-deposited perovskite enhances both the stability and efficiency of perovskite solar cells by suppressing nonradiative recombination
Journal Article
Effect of Cssup.+ Doping on the Carrier Dynamics of MAPbIsub.3 Perovskite
Organic inorganic perovskite materials have received increasing attention in the optoelectronic field because of their unique properties. The ultrafast dynamics of photogenerated carriers determine photoelectric conversion efficiency, thus, it is feasible to influence the dynamics behavior of photogenerated carriers by regulating A-site cations. This paper mainly used transient absorption spectra (TAS) technology to study the photogenerated carriers relaxation processes of organic–inorganic perovskite Cs[sub.x]MA[sub.1−x]PbI[sub.3] materials at different x values. Three sets of time constants were obtained by global fitting at different values of x. The experimental results showed that the crystal structure of perovskite could be affected by adjusting the Cs[sup.+] doping amount, thereby regulating the carrier dynamics. The appropriate amount of A-cation doping not only maintained the organic–inorganic perovskite crystal phase, but also prolonged the photogenerated carrier’s lifetime. The 10% Cs[sup.+] doping Cs[sub.x]MA[sub.1−x]PbI[sub.3] perovskite has potential for solar cell applications. We hope that our research can provide dynamics support for the development of organic–inorganic perovskite in solar cells.
Journal Article
In Search of a Double Perovskite in the Phase Triangle of Bromides CsBr-CuBr-InBrsub.3
New bromide compounds A[sub.2]B[sup.I]B[sup.III]Br[sub.6] with a double perovskite structure provide variety and flexibility of optoelectronic properties, and some of them are of poor toxicity in comparison with such popular lead halides. The promising compound with a double perovskite structure was proposed recently for the ternary system of CsBr-CuBr-InBr[sub.3]. Analysis of phase equilibria in the CsBr-CuBr-InBr[sub.3] ternary system showed stability of the quasi-binary section of CsCu[sub.2]Br[sub.3]-Cs[sub.3]In[sub.2]Br[sub.9]. Formation of the estimated phase Cs[sub.2]CuInBr[sub.6] by melt crystallization or solid-state sintering was not observed, most likely, as a result of higher thermodynamic stability of binary bromides CsCu[sub.2]Br[sub.3] and Cs[sub.3]In[sub.2]Br[sub.9]. The existence of three quasi-binary sections was observed, while no ternary bromide compounds were found.
Journal Article
The Study of SCR Mechanism on LaMnsub.1−xFeIx/IOsub.3 Catalyst Surface Based DFT
Perovskite SCR catalysts have become a hot research topic in the field of de-NO[sub.x] catalyst development. This article selects LaMnO[sub.3] with high performance as the research object, modifies the catalyst by doping some iron elements instead of manganese elements, and applies density functional theory to study its reaction mechanism, providing theoretical reference for further research on perovskite. Research has found that several main reactants such as NH[sub.3], NO, and O[sub.2] can form stable adsorption at the active site, with NO more inclined to adsorb at the nitrogen atom end at the active site. The oxidation of O[sub.2] molecules after adsorption is greater than that of the active site. The adsorption capacity of the Mn active site of the catalyst before modification on the above molecules is weaker than that of the Fe active site introduced after modification. Under both anaerobic and aerobic conditions in the SCR reaction process, NH[sub.3] molecules are first adsorbed at the active site, and then influenced by lattice oxygen under anaerobic conditions. Under aerobic conditions, they are gradually dehydrogenated and produce NH[sub.2] and NH radicals. These two radicals react with NO molecules to form intermediate products in the form of NH[sub.2]NO and NHNO molecules. Due to the instability of the intermediate products, they ultimately decompose into N[sub.2] and H[sub.2]O molecules. The introduction of Fe active sites can increase the generation of NH[sub.2] and NH radicals during the reaction process and simplify the reaction process between NH[sub.2] radicals and NO molecules, which will be conducive to the completion of the reaction.
Journal Article
Growth of Hybrid Perovskite Crystals from CHsub.3NHsub.3PbIsub.3–xClIx/I Solutions Subjected to Constant Solvent Evaporation Rates
In this work, we subjected hybrid lead-mixed halide perovskite (CH[sub.3]NH[sub.3]PbI[sub.3-x]Clx) precursor inks to different solvent evaporation rates in order to facilitate the nucleation and growth of perovskite crystals. By controlling the temperature of perovskite solutions placed within open-air rings in precise volumes, we established control over the rate of solvent evaporation and, thus, over both the growth rate and the shape of perovskite crystals. Direct utilization of diluted lead-mixed halide perovskites solutions allowed us to control the nucleation and to favor the growth of only a low number of perovskite crystals. Such crystals exhibited a clear sixfold symmetry. While crystals formed at a lower range of temperatures (40-60 °C) exhibited a more compact dendritic shape, the crystals grown at a higher temperature range (80-110 °C) displayed a fractal dendritic morphology.
Journal Article