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Summary In the realm of solar cells, currently, the carbon‐electrode‐based, all‐inorganic perovskite solar cells (C‐IPSCs) based on cesium lead mixed halide perovskites have drawn much attention. Band‐gap tunability and environmental stability of these perovskites (CsPbIBr2) have been gaining attraction as a suitable absorber material for device fabrication. Fabrication of a high‐performing and stable C‐IPSC based on CsPbIBr2 is a challenging process due to high‐temperature fabrication, poor solution deposition of perovskite film, and high recombination at perovskite/carbon interface. In this work, a simple single‐step deposition process was adopted to engineer a good quality perovskite film by replacing conventional precursors with DMSO‐adducts of lead halide (PbX2). Incorporation of the adduct‐based precursor enables crystallization of CsPbIBr2 at a low temperature (~150°C). This enhances the crystallinity of the film, improves the grain size and defects passivation which imparts endurance to the perovskite against phase change and thermal stress. Thereby, enhancing the light absorption and suppressing the non‐radiative recombination in CsPbIBr2 film. As a result, the open‐circuit voltage is enhanced up to 1.18 V and fill factor up to 57%, further improving the power conversion efficiency by 59.4% leading to a champion device efficiency of 5.9%. Adduct‐based C‐IPSC displayed substantial enhancement of ambient stability and the adduct‐based perovskite exhibited excellent thermal stability.

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The asymmetric unit of the title salt, C4H12NO2 +·C6H2N3O7 −, contain two bis­(2-hy­droxy­eth­yl)ammonium cations and two picrate anions. An intra­molecular N—H⋯O hydrogen bond occurs in each cation. In the crystal, mol­ecules are linked via O—H⋯O and N—H⋯O hydrogen bonds, which generate two R 2 1(6), an R 2 2(10) and an R 2 2(13) graph-set ring motifs. There are also a number of C—H⋯O hydrogen bonds present. The sum of these inter­actions leads to the formation a three-dimensional structure.

In the title adduct, C7H7NO3 .C7H10N2, the dihedral angle betwen the benzene ring and pyridine rings is 9.60 (8)° while the nitro group attached to the benzene ring makes a dihedral angle of 21.76 (13)°. The hydroxyl O atom deviates by 0.0247 (15) Å from the plane of the benzene ring. The crystal packing features O—H⋯N hydrogen bonds.

The synthesis, growth and structure of a novel organic third order nonlinear optical (NLO) crystal namely, N,N,N 0 ,N 0 -tetramethylethylenediammonium-bis(4-nitrophenolate) (TMEDA4NP) is presented. The solubility of the compound in methanol and acetonitrile solvents is compared and the growth conditions were optimized. Single crystals of TMEDA4NP were grown in acetonitrile solvent using a slow evaporation technique at 303 K. The crystal structure elucidated from single crystal X-ray diffraction analysis at 293 K showed that the title compound crystallizes in a monoclinic crystal system with space group C2/c. The molecular structure was further confirmed by modern spectroscopic techniques like FT-IR, FT-NMR, UV-Vis-NIR and Fluorescence. The transparency in the visible region and hence the feasibility of the crystal for NLO applications was established from UV-Vis-NIR study. Fluorescence emission of the crystal also revealed that the title compound can serve as a photoactive material. The protonation of TMEDA4NP was unambiguously confirmed from the NMR data. Thermo gravimetric analysis (TGA) showed that TMEDA4NP was thermally stable up to 110 C. The mechanical strength of the crystal was assessed by a Vickers microhardness tester. Etching studies were carried out on the (100) plane of the as grown surface of the crystal. Third order susceptibility measured using the Z scan technique by employing a picosecond Nd-YAG laser indicates that the title compound can serve as a promising candidate for third order NLO applications.

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