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Metal halide perovskites show remarkable optical properties and useful applications in optoelectronic devices. However, the instability of three-dimensional (3D) metal halide perovskites limits their applications, leading to the emergence of more stable two-dimensional (2D) metal halide perovskites. Herein, we present a facile synthesis of the 2D hybrid metal halide perovskite (EDA)(MA)n−1PbnBr3n+1 (EDA: ethylene diammonium, MA: methylammonium), where n = 1–6, and MAPbBr3 perovskite layers using an anti-solvent co-precipitation technique. The synthesized materials exhibited tunable optical properties, and the color emissions of pure EDAPbBr4 and (EDA)(MA)2Pb3Br10 perovskites were successfully tailored by altering halide anion layers. The band gap decreases as the value of n in the (EDA)(MA)n−1PbnBr3n+1 compound increases from 1 to 6. The as-prepared materials were characterized using X-ray diffraction (XRD) technique, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Finally, the stability of the 2D hybrid metal halide perovskite structures was evaluated under ambient conditions over different periods. Their tunable color emission was investigated and robust fluorescence was observed after 55 days. Thus, this study provides valuable insights into the synthesis and characterization of 2D hybrid metal halide perovskites for tunable color emission, highlighting their potential for use in various optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this work, we report the design and successful synthesis of two new heteroleptic polypyridyl Ru(II) complexes (SD-5 and SD-6), by incorporating hetero-aromatic electron-donating N-alkyl-2-phenylindole moieties into the ancillary ligand. These novel ruthenium complexes were used as photosensitizers for dye-sensitized solar cells. The primary objective was to investigate the electron-donating effect of the indole segments on the photo-related properties and the influence of the length of terminal alkyl chains tethered to N-indole on the charge recombination resistance. The chemical structures of both targeted compounds were confirmed via FT-IR, 1H-NMR and mass spectrometry. Under the same device fabrication conditions, the photovoltaic performance of SD-6 outperformed that of SD-5 and N719 with an overall efficiency of 8.14% (JSC = 19.21 mA cm−2, VOC = 0.675 V and FF = 62.7%), compared to 7.74% of N719 and 4.99% of SD-5. The enhanced photovoltaic power of SD-6 can be attributed to the presence of long alkyl antennas (–C18H37) in SD-6; it reduced the intermolecular aggregation of dyes and suppressed charge recombination, thus resulting in enhanced JSC and VOC values, respectively, compared to its analog SD-5. Furthermore, the presence of indole moieties with long alkyl chains in the ancillary ligand enhanced the photovoltaic performance compared to N719 with bi-anchoring ligands. The photovoltaic and EIS measurements were consistent with the equilibrium molecular geometry calculated using density functional theory (DFT). The structure–property relationships have been discussed in detail. [ABSTRACT FROM AUTHOR]

Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenability and improved optical properties compared to their single metal halide perovskites. It is thus valuable to investigate compositional changes in lead halide perovskites to explore energy changes. Herein, we report the synthesis of a lead to lead free hybrid perovskite solid solution (CH3NH3Pb1−xCuxBr3) as nanoparticles and films. The increasing concentration of Cu2+ ions in the site of the Pb2+ ion in the perovskite shifted the diffraction peaks to a larger angle. Uniform spherically shaped nanoparticles were synthesized by a wet chemical method, the higher Cu2+ concentration leads to agglomeration, producing sheet like morphologies. However, the deposition of thin films of CH3NH3Pb1−xCuxBr3 perovskite solid solution shows that well defined morphologies begin to appear with increasing concentrations of Cu2+ in the perovskite structure. The as-prepared bulk lead free CH3NH3CuBr3 perovskite shows a band gap of 1.65 eV. A blue shift in photoluminescence (PL) was observed with copper enriched hybrid perovskites. [ABSTRACT FROM AUTHOR]

This contribution reports the deposition of new zinc based lead free all inorganic 3D CsZnCl2I perovskite thin films using aerosol assisted chemical vapour deposition (AACVD) at 100 °C. Room tempertaure optical measurements performed on the as-deposited thin films showed two absorption peaks. Upon 325 nm excitation, the CsZnCl2I perovskite thin film showed broad band white light emission having two peaks, which cover the entire visible range of the spectrum. This is the first example of white light emission from 3D all-inorganic lead free mixed halide CsZnCl2I perovskites. [ABSTRACT FROM AUTHOR]

Inorganic lead halide perovskite solar cells with mixed halides have achieved reasonable power conversion efficiency with the advantage of enhanced stability. In this work, we report the fabrication of an all-inorganic cesium lead bromoiodide based planar perovskite solar cell with a ZnO electron transport layer. The method described herein includes the use of one step spin coating solution processing using a solvent mixture (DMF + DMSO) to avoid the solubility issues of CsPbBr2I perovskite in DMF. The substrate temperature during spin coating was found to be a critical parameter to generate the required crystalline morphology of the perovskite thin films. Post-annealing of the as-deposited perovskite film at 275 °C led to the formation of the cubic phase of CsPbBr2I with an optical band gap of 2.06 eV. Interestingly, cubic shaped CsPbBr2I morphology was obtained via single-step spin-coating processing that otherwise required two-step solution deposition of the hybrid perovskite. The best performing devices achieved 4.8% power conversion efficiency with minimal hysteresis and enhanced thermal and photo-stability. Owing to enhanced thermal and photo-stability, inorganic perovskites appear as viable alternatives to hybrid organic–inorganic perovskites for solar cell applications. [ABSTRACT FROM AUTHOR]

High-purity anatase nanocrystals were prepared by using a low-temperature surfactant-assisted solution-phase method. Titanium tetra-isopropoxide (TTIP) was used as a precursor, polyethylene glycol (PEG) as a surfactant, and isopropyl alcohol (IPA) and water as solvent. An isopropanolic solution of TTIP and PEG was mixed with an aqueous acidic solution at about 60 °C to yield a whitish sol that, after being baked at 60 °C for 6 hours, was transformed into phase-pure anatase crystals with dimensions of about 8 nm. By varying the mass of the PEG surfactant from 0.5 to 2 g, the particle dimensions could be controlled to be between 8 and 11 nm. Thermogravimetric analysis in combination with transmission electron microscopy (TEM), XRD, and Raman, Ultraviolet-visible (UV-vis) and infrared spectroscopies showed the nanocrystals with dimensions of 8–11 nm to be composed of an anatase lattice with hydroxyl bound to the surface. These nanocrystals showed much improved efficiency for photodegradation of methylene blue as compared with the commercial Degussa P25, due to the extraordinarily increased surface area. These findings may inspire the engineering of highly active subnanometer-sized nanocrystals for energy- and environment-related applications. [ABSTRACT FROM AUTHOR]

A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth were found to be significantly altered by changes in the deposition temperature. Oleylamine capped nanosheets and the as-deposited thin films by AACVD were characterized by powder X-ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, and all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectrochemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), by switching the applied potential. [ABSTRACT FROM AUTHOR]

First row transition metal complexes (Ni, Co, Cu, Zn) with N,N-disubstituted-N′-acylthiourea ligands have been synthesized and characterized. Bis(N,N-diisopropyl-N′-cinnamoylthiourea)nickel was found to have the lowest onset temperature for thermal decomposition. Thin film deposition of Ni, Co, and Zn sulfides by aerosol assisted chemical vapor deposition from their respective N,N-diisopropyl-N′-cinnamoylthiourea complexes at 350 °C has been demonstrated. [ABSTRACT FROM AUTHOR]

In this study, we report the synthesis of a novel heteroleptic Ru(ii)-sensitizer, (Ru(2,2′-bipyridine-4,4′-dicarboxylic acid)-4,4′-bis(4-piperidin-1-yl)phenyl ethenyl)-(2,2′-bipyridine) (NCS)2, denoted as SD-1; moreover, its photophysical, electrochemical, and photovoltaic performances were compared with those of N719 and K77-7 (N,N′-diaryl Ru-sensitizer, namely Ru(2,2′-bipyridine-4,4′-dicarboxylic-acid)-4,4′-bis(2-(4-N,N′-diphenylaminophenyl)ethenyl)-2,2′-bipyridine (NCS)2). The photovoltaic performance of SD-1 outperformed those of N-719 and K77-7, particularly in the red region, and the overall efficiency of SD-1 was 8.5% as compared to 8.0% of K77-7 and 7.7% of N719 under the same experimental device conditions. The superior light harvesting efficiency of SD-1 can be attributed to the strong electron donor sp3-nitrogen, which is attached to two sp3-carbons (dialkyl), whereas in the case of K77-7, all carbon atoms attached to the sp3-nitrogen are sp2, which decrease the electron density on the latter and minimize the electron-donating power of the ancillary ligand in K77-7. To gain a quantitative understanding of the electron density on nitrogen in SD-1 and K77-7, first-principle calculations using molecular and thermodynamic descriptors, such as frontier molecular orbitals, ground-state oxidation potential (GSOP), excited-state oxidation potential (ESOP), optical gap (E0–0), and charge distributions, were conducted in solution. In addition, for understanding the anchored structures of dyes on Ti24O48, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were utilized. Results of computational studies are in excellent agreement with the experimental results, which can be used as a screening tool for the design of more efficient molecular motifs for DSSCs. [ABSTRACT FROM AUTHOR]

In this study, tris-heteroleptic Ru(ii) sensitizers denoted as SD-15 and SD-16 with a 4,4′,5,5′-tetramethyl-1H,1′H-2,2′-bis-imidazole moiety as the ancillary ligand were designed, synthesized and characterized using FTIR-ATR, 1H-NMR and UV-vis spectrophotometry. Structural modulations resulted in a red shift in the low-energy metal-to-ligand charge transfer (MLCT) absorption peak. The novel bis-imidazole based Ru(ii) sensitizer was adsorbed on a TiO2 surface via–COOH anchoring groups. The band gap, and the ground and excited state oxidation potentials were measured. The photovoltaic performance of the as-fabricated solar cells was measured and showed that the presence of bis-imidazole provided more negative free energy for dye regeneration (−ΔGregeneration) and less driving force for electron injection (−ΔGinjection) into the conduction band edge of TiO2. Therefore, the use of SD-15 and SD-16 resulted in lower JSC values of 10.20 and 3.52 mA cm−2, respectively, than N719. The open-circuit photovoltage (VOC) of SD-15 and SD-16 was 0.58 and 0.52 V, respectively, less than N719 under the same experimental conditions due to the decreased eTiO2 lifetime of 0.71 ms compared to 8.8 ms of N719 for the injected electrons that was calculated using impedance measurements. Our efforts in this research program led to the development of more stable Ru(ii) complexes compared to N719 NCS-based complexes; however, the conversion efficiency was lower. Hence, the fine-tuning of bi-imidazole is needed to identify more efficient NCS-free Ru(ii) sensitizers for higher efficiency DSSCs. [ABSTRACT FROM AUTHOR]

We report the preparation of a lead free inorganic perovskite by a facile wet-chemical method using HCl as a solvent at room temperature. The cesium perovskite CsCuCl3 material was characterized by powdered X-ray diffraction (p-XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX) spectroscopy. Ultraviolet/Visible (UV-Vis) and steady state photoluminescence (PL) spectroscopy were also carried out on the material. CsCuCl3 showed promising optical properties with a band gap of 2.6 eV. The material was tested as a fluorescent sensor for the detection of metal ions and as a selective fluorescent chemodosimeter for Pb2+ ions. The substitution of Cu2+ ions by Pb2+ in CsCuCl3 proves the success of the chemodosimetry approach for the detection of Pb2+ ions. [ABSTRACT FROM AUTHOR]

Phase pure SnS nanosheets were synthesized by a hot injection method from a new single molecular precursor (SMP), dibutyl-bis(piperidinedithiocarbamato)tin(iv) in oleylamine at 230 °C. The tin complex was characterized by single crystal X-ray crystallography, nuclear magnetic resonance, thermogravimetry and microelemental analysis. The complex is thermally stable up to 260 °C, after which it decomposes in a single step with a major mass loss between 260 °C and 300 °C. The thermolysis of the as-prepared precursor was carried out in oleylamine between 190 and 230 °C. The formation and shape evolution of SnS was investigated using high resolution electron microscopy. The mechanism of the time dependent growth of SnS from spherical particles into nanosheets is proposed. [ABSTRACT FROM AUTHOR]

Ultra-small PbSe nanocrystals (NCs) were synthesized via a 'one-pot' approach in olive oil as the reaction medium and capping agent. The optical spectra showed discernible blue shifts in the absorption band edges (570-780 nm) due to strong quantum confinement effects and photoluminescence (PL) spectra showed significant strong emission peaks in the range of 780-850 nm. The broad peaks in the powder X-ray diffraction (p-XRD) pattern indicate the ultra-small size of the as-prepared NCs. These NCs were used to construct an extremely thin absorber (ETA) solar device after surface modification. The preliminary results indicate their potential as light harvesting entities in nanostructure based solar cells. [ABSTRACT FROM AUTHOR]

Ultrafast transient absorption measurements have been used to study multiple exciton generation in solutions of PbS nanoparticles vigorously stirred to avoid the effects of photocharging. The threshold and slope efficiency of multiple exciton generation are found to be 2.5 ± 0.2 × Egand 0.34 ± 0.08, respectively. Photoemission measurements as a function of nanoparticle size and ageing show that the position of the valence band maximum is pinned by surface effects, and that a thick layer of surface oxide is rapidly formed at the nanoparticle surfaces on exposure to air. [ABSTRACT FROM AUTHOR]

The low temperature growth of crystalline PbS films has been achieved on plastic substrates by CVD using a xanthate. The possible mechanism involved in this low temperature deposition has been probed by density functional theory calculations. [ABSTRACT FROM AUTHOR]

We describe for the first time the use of a single source precursor to deposit thin films and nanocrystals of palladium selenide. [ABSTRACT FROM AUTHOR]

Correction for ‘Facile synthesis of phosphine free ultra-small PbSe nanocrystals and their light harvesting studies in ETA solar cells’ by Javeed Akhtar, et al., Dalton Trans., 2014, 43, 16424–16430. [ABSTRACT FROM AUTHOR]

At the ultrathin scale, nanomaterials exhibit interesting chemical and physical properties, like flexibility, and polymer-like rheology. However, to limit the dimensions of composite nanomaterials at the ultrathin level is still a challenging task. Herein, by adopting a new low temperature single step and single pot wet chemical approach, we have successfully fabricated two dimensional (2D) mixed oxide ZnO-Fe 2 O 3 dendritic nanosheets (FZDNSs). Various control experimental outcomes demonstrate that precursor salts of both the metals are crucial for the formation of stable 2D FZDNSs. The obtained FZDNSs not only exhibit the best photoreduction performance but also much enhanced electrocatalytic performance. This work will provide a promising avenue for the synthesis of cost effective transition metal mixed oxide based 2D nanosheets having wide ranging applications., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth were found to be significantly altered by changes in the deposition temperature. Oleylamine capped nanosheets and the as-deposited thin films by AACVD were characterized by powder X-ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, and all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectrochemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), by switching the applied potential.

First row transition metal complexes (Ni, Co, Cu, Zn) with N,N-disubstituted-N'-acylthiourea ligands have been synthesized and characterized. Bis(N,N-diisopropyl-N'-cinnamoylthiourea)nickel was found to have the lowest onset temperature for thermal decomposition. Thin film deposition of Ni, Co, and Zn sulfides by aerosol assisted chemical vapor deposition from their respective N,N-diisopropyl-N'-cinnamoylthiourea complexes at 350 °C has been demonstrated.

The reaction of two equivalents of (TMEDA)Li[(EP(i)Pr(2))(TeP(i)Pr(2))N] (E = S, Se) with NiBr(2)(DME) in THF at 23 degrees C yields homoleptic complexes of heterodichalcogenido PNP ligands Ni[(EP(i)Pr(2))(TeP(i)Pr(2))N](2) (2, E = S; 3, E = Se). Similarly, the complexes Ni[(P(i)Pr(2))(EP(i)Pr(2))N](2) (4, E = Se; 5, E = Te) are obtained by in situ deprotonation of the neutral monochalcogenides E=P(i)Pr(2)NP(H)(i)Pr(2) (E = Se, Te) with (n)BuLi in THF at -78 degrees C followed by addition of NiBr(2)(DME). The complexes 2-5 have been characterised by multinuclear ((1)H, (31)P, (77)Se and (125)Te) NMR spectroscopy in solution and by X-ray crystallography in the solid state, the results of which show that they all exist as the square planar, trans isomers. Aerosol-assisted chemical vapour deposition (AACVD) of Ni[(SeP(i)Pr(2))(TeP(i)Pr(2))N](2) yields crystalline Ni(0.51)Te films at 450-500 degrees C, which were analysed by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS).