The moisture‐induced structural decomposition of lead halide perovskites is the major challenge in solar cells and light‐emitting diodes based on perovskites as the active material. The presence of moisture results in the structural conversion of cubic 3D CsPbBr3 nanocrystals to 2D CsPb2Br5 nanosheets before its decomposition to PbBr2. The capping agent used, oleyl amine, plays a crucial role in this structural transformation. The presence of moisture converts the capping agent, oleyl amine, to its salt, which transforms the 3D CsPbBr3 perovskite nanocrystals to 2D CsPb2Br5 nanosheets. Further, these CsPb2Br5 nanosheets decompose to trigonal PbBr2, in the presence of higher amounts of water. Also, the amount of capping agent, oleyl amine, plays an important role in the rate of moisture‐induced structural transformations. The rate of decomposition increases with the amount of oleyl amine used as a result of the reaction of water with the excess ligands. By revealing the exact mechanism of the structural alterations in the presence of water, new design strategies can be used to prevent the decomposition of perovskites.

ABSTRACT:A high-level ab initio Hartree-Fock/Møller-Plesset 2 and density functional theory quantum chemical calculations were performed on p-chlorobenzaldehyde diperoxide energetic molecule to understand its bond topological, electrostatic, and energetic properties. The optimized molecular geometry for the basis set 6-311G** exhibit chair diperoxide ring and planar aromatic side rings. Although the diperoxide ring bear same type of side rings, surprisingly, both the rings are almost perpendicular to each other, and the dihedral angle is 96.1 . The MP2 method predicts the OAO bond distance as $1.466 Å . The charge density calculation reveals that the CAC bonds of chlorobenzaldehyde ring have rich electron density and the value is $2.14 e Å À3. The maximum electron density of the OAO bonds does not lie along the internuclear axes; in view of this, a feeble density is noticed in the ring plane. The high negative values of laplacian of CAC bonds (approximately À22.4 e Å À5) indicate the solidarity of these bonds, whereas it is found too small (approximately À1.8 e Å À5 for MP2 calculation) in OAO bonds that shows the existence of high degree of bond charge depletion. The energy density in all the CAC bonds are found to be uniform. A high electronegative potential region is found at the diperoxide ring which is expected to be a nucleophilic attack area. Among the bonds, the OAO bond charge is highly depleted and it also has high bond kinetic energy density; in consequence of this, the molecular cleavage is expected to happen across these bonds when the material expose to any external stimuli such as heat or pressure treatment.

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Currently, the TiO2/CdS photoanodes based dye sensitized solar cells (DSSCs) have shown extraordinary developments in the photo conversion e ciency. In this report, pristine TiO2, CdS and various molar ratios of TiO2/CdS photoanodes were prepared by one step microwave irradiation route and followed by doctor blade method. The sheet like morphology of the TiO2 and CdS nanoparticles were clearly evident from the SEM and TEM images. A signi cant reduction band gap with enhanced light absorption and rapid prevention of electron hole pair was explored by UV-DRS and PL studies. The photocurrent densityvoltage (J-V) and electrochemical impedance (EIS) characteristics were analyzed for assembled solar cell. The photo-conversion e ciency of 12.8% was obtained with the con guration TiO2/CdS (200 mg) that represent a 2.5 fold increment compared to bare TiO2 (5.33%) as well as commercial Pt (6.11%). The experimental results are discussed.

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Voluntary help is the charity. Only by adding material. The doesn’t mean you have to help. The big charity is the one who uses what he does not need for his life and gives the rest to others. Eleven accounts best illustrate this equivalence of giving to the other side of receipt. But in our lives, we adhere to giving as soon as we receive something. the best quality is to give in advance to other as you would to point out what is being done in this world is for the hereafter our ancestors considered it unethical to expect that. Compassion makes a gift realizes that Mallam. In this world we are the glory off the charity that lasts after death.

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