Highly Efficient and Stable Inverted Perovskite Solar Cell Using Pure δ-FAPbI3 Single Crystals

Pure δ-formamidinium lead triiodide (δ-FAPbI3 ) single crystal for highly efficient perovskite solar cell (PCS) with long-term stability is prepared by a new method consisting of liquid phase reaction of FAI and PbI2 in N,N-dimethyl formamide and antisolvent crystallization using acetonitrile. In this method, the incorporation of any impurity into the crystal is excluded by the molecular recognition of the crystal growth site. This pure crystal is used to fabricate α-FAPbI3 inverted PSCs which showed excellent power conversion efficiency (PCE) due to much-reduced trap-states. The champion device exhibited a high PCE of 23.48% under the 1-Sun condition. Surface-treated devices with 3-(aminomethyl)pyridine showed a significantly improved PCE of 25.07%. In addition, the unencapsulated device maintained 97.22% of its initial efficiency under continuous 1-Sun illumination for 1,000 h at 85 °C in an N2 atmosphere ensuring long-term thermal and photo stabilities of PSCs, whereas the control device kept only 89.93%.

Correction: A hybrid blue perovskite@metal–organic gel (MOG) nanocomposite: simultaneous improvement of luminescence and stability

Correction for ‘A hybrid blue perovskite@metal–organic gel (MOG) nanocomposite: simultaneous improvement of luminescence and stability’ by Samraj Mollick et al., Chem. Sci., 2019, 10, 10524–10530, DOI: 10.1039/C9SC03829A.

A hybrid blue perovskite@metal-organic gel (MOG) nanocomposite: simultaneous improvement of luminescence and stability

Blue light-emitting hybrid perovskite nanocrystals (NCs) are promising candidates for optoelectronic applications. However, these NCs suffer severely from low photoluminescence quantum yield (PLQY) and inferior stability under working conditions. Herein, we report, for the first time, a simultaneous dramatic improvement in both the luminescence and the stability of hybrid perovskite NCs through embedding in a porous metal-organic gel (MOG) matrix. The nanocomposite (EAPbBr3@MOG, EA: ethylammonium) shows sharp emission in the intense blue region (λ max < 440 nm), with a substantial ten-fold enhancement in the PLQY (∼53%) compared with EAPbBr3 NCs (PLQY ∼5%). Incorporation of perovskite NCs into the soft MOG matrix provides the additional benefits of flexibility as well as water stability. As a proof of principle, these nanocomposites were further utilized to fabricate a white light-emitting diode. The combination of high brightness, stability and flexibility of these nanocomposites could render them viable contenders in the development of efficient, blue light-emitting diodes for practical applications.

Precursor-driven selective synthesis of hexagonal chalcocite (Cu2S) nanocrystals: structural, optical, electrical and photocatalytic properties

A new single-source precursor, [Cu(mdpa)₂][CuCl₂], is used to prepare selectively high chalcocite (Cu₂S) with excellent photodegradation of Congo red (CR).

An orthogonal ferromagnetically coupled tetracopper(ii) 2 × 2 homoleptic grid supported by µ-O4bridges and its DFT study

A pyrazole based ditopic ligand (PzOAP), prepared by the reaction between 5-methylpyrazole-3-carbohydrazide and methyl ester of imino picolinic acid, reacts with Cu(NO3)2.6H2O to form a self-assembled, ferromagnetically coupled, alkoxide bridged tetranuclear homoleptic Cu(II) square grid-complex [Cu4(PzOAP)4(NO3)2] (NO3)2.4H2O (1) with a central Cu4[micro-O4] core, involving four ligand molecules. In the Cu4[micro-O4] core, out of four copper centers, two copper centers are penta-coordinated and the remaining two are hexa-coordinated. In each case of hexa-coordination, the sixth position is occupied by the nitrate ion. The complex 1 has been characterized structurally and magnetically. Although Cu-O-Cu bridge angles are too large (138-141 degrees) and Cu-Cu distances are short (4.043-4.131 A), suitable for propagation of expected antiferromagnetic exchange interactions within the grid, yet intramolecular ferromagnetic exchange (J = 5.38 cm(-1)) is present with S = 4/2 magnetic ground state. This ferromagnetic interaction is quite obvious from the bridging connections (d(x2-y2)) lying almost orthogonally between the metal centers. The exchange pathways parameters have been evaluated from density functional calculations.

Holliday junction resolvases encoded by homologous rusA genes in Escherichia coli K-12 and phage 82

The RusA protein of Escherichia coli is an endonuclease that can resolve Holliday intermediates and correct the defects in genetic recombination and DNA repair associated with inactivation of RuvAB or RuvC. The structure of the rusA gene, its organisation in the genome, and its interaction with the Ruv and RecG proteins have been investigated. Recombinant plasmids carrying rusA were identified by their ability to make ruv mutants resistant to UV light. The gene was located to an open reading frame encoding a polypeptide of 120 amino acids. It forms the fifth gene in an operon containing a chain of short, interlinked open reading frames. A similar arrangement was found in the genome of the lambdoid bacteriophage, 82. The two rusA genes show 95% sequence identity. The E. coli operon forms part of the defective lambdoid prophage, DLP12, and is probably derived from a phage related to 82 and PA-2. rusA appears to be very poorly expressed in E. coli, but can be activated by insertion of IS2 or IS10 upstream of the coding sequence to promote transcription. These insertions arise spontaneously in ruv strains as suppressors of the mutant phenotype. Deletion of rusA from the chromosome of either wild-type or ruv mutant strains has no obvious effect on recombination or sensitivity to UV light. Multicopy plasmids expressing RusA alone make ruvA, ruvB, and ruvC mutants resistant to UV light. Suppression depends critically on RecG.

Resolution of Holliday intermediates in recombination and DNA repair: indirect suppression of ruvA, ruvB, and ruvC mutations

The ruvA, ruvB, and ruvC genes of Escherichia coli provide activities that catalyze branch migration and resolution of Holliday junction intermediates in recombination. Mutation of any one of these genes interferes with recombination and reduces the ability of the cell to repair damage to DNA. A suppressor of ruv mutations was identified on the basis of its ability to restore resistance to mitomycin and UV light and to allow normal levels of recombination in a recBC sbcBC strain carrying a Tn10 insertion in ruvA. The mutation responsible was located at 12.5 min on the genetic map and defines a new locus which has been designated rus. The rus suppressor works just as well in recBC sbcA and rec+ sbc+ backgrounds and is not allele specific. Mutations in ruvB and ruvC are suppressed to an intermediate level, except when ruvA is also inactive, in which case suppression is complete. In all cases, suppression depends on RecG protein, a DNA-dependent ATPase that catalyzes branch migration of Holliday junctions. The rus mutation activates an additional factor that probably works with RecG to process Holliday junction intermediates independently of the RuvAB and RuvC proteins. The possibility that this additional factor is a junction-specific resolvase is discussed.