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Organic-inorganic hybrid perovskites are promising candidates for several optoelectronic devices, such as solar cells, light-emitting diodes, and photodetectors. Particularly, methylammonium lead iodide (MAPbI3) has been widely used as a light harvester in photovoltaic devices. However, MAPbI3 has a fatal weakness in long-term stabilities of humidity and high temperature. In this work, we fabricated extremely stable quasi-2D structures of hybrid perovskite films by introducing methylammonium formate (MAF) and propylammonium formate (PAF) ionic liquids. We found that the perovskite films using the ionic liquids exhibited low-dimensional structures to contribute to improved environmental and thermal stabilities. We believe that this work elucidates the importance of solvent mediated crystal growing process and somehow guides the design of stable low-dimensional perovskites. [ABSTRACT FROM AUTHOR]

First-principles calculations predict that the cubic phase of methylammonium lead iodide (CH3NH3PbI3), a well-known perovskite material containing no rare metals, will show thermoelectric properties for temperatures below 200 °C. Our work confirms this prediction. A densely packed compact of CH3NH3PbI3 which enables us to measure the properties was easily fabricated from the powder by uniaxial pressure formation. Although the electrical resistance was high, excellent thermal conductivity was observed for the use of CH3NH3PbI3 as a thermoelectric material. [ABSTRACT FROM AUTHOR]

In this work, the effects of annealing temperature and time for one-step fabrication of mixed metal halide perovskite films were investigated. The photovoltaic performance of perovskite solar cells (PSCs) improved from 8.30 to 10.85% after being annealed at 100 °C for 10 min and exhibited negligible photocurrent hysteresis when prepared at an ambient humidity of 70%. Besides, a high annealing temperature for a short time (150 °C; 1 min) shows comparable power conversion efficiency with perovskite annealed at 100 °C for 10 min. The electronic properties of PSCs were characterized by photo induced charge extraction via linearly increasing the voltage (photo-CELIV), impedance, and intensity modulated photovoltage spectroscopy. Our finding suggests that the improvement in photovoltaic performance is correlated to the improved charge mobility, suppressed charge trapping, and prolonged recombination lifetime. [ABSTRACT FROM AUTHOR]

Thiuram disulfide intercalates of lead(II) and cadmium(II) were prepared by the reaction of binary layered metal iodides with five dithiocarbamates in air. The intercalates were characterized by elemental analysis, Powder X-ray diffraction (XRD), infrared (IR), ultraviolet–visible spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM) techniques. IR showed increased contribution of the thioureide bond and the presence of weak disulfide stretching frequency. Powder XRD showed the characteristic intermediate 2θ signal confirming the intercalation. Powder XRD clearly differentiated intercalates from the iodinated product of dithiocarbamate. As the bulkiness of substituents on disulfide increased, “d” also increased. The higher thermal stability associated with intercalates clearly suggests a strong ionic interaction and a difficult de-intercalation. SEM images of lead intercalates indicated crystalline nature. The intercalates appeared as rods or spheres. The diallyl-intercalate, [PbI2](H5C3)2NCSS-SSCN(C3H5)2(where (H5C3)2NCSS-SSCN(C3H5)2is diallylthiuram disulfide), shows “net like structures.” Intercalation of oxidized dithiocarbamates in the “galleries” of layered PbI2/CdI2is observed. HRTEM and AFM analysis of intercalates showed the particles to be nano-rods. [ABSTRACT FROM PUBLISHER]

Developments in the field of organic-inorganic lead halide perovskite based solar cells have metaphorically opened the door to an exciting new solid state photovoltaic technology that retains the low cost and processability benefits of dye sensitised solar cells (DSCs). Encouraging device efficiencies of greater than 10% on both titania and alumina, and as a planar device, have been reported in the literature. Here we report the characteristics of a series of lead iodide/bromide perovskites. As one might expect, changing the halide(s) alters the crystal structure and band gap of the perovskite which results in the possibility of vivid and colourful solar cells; a characteristic which is seen as one of the main benefits of DSCs. X-ray diffraction and scanning electron microscopy with elemental mapping via energy dispersive X-ray analysis has been used to characterise perovskites on sensitised thin films. UV-vis and diffuse reflectance has been used to study the optical characteristics of crystallised perovskite thin films. Finally device performance is evaluated and suitability for use in photovoltaic devices is discussed. [ABSTRACT FROM AUTHOR]

A new Lewis-base adduct of the iodo-bridged lead(II) compound {[PbI2(DPP)]·DMF} n (1) (DPP = 4,7-diphenyl-1,10-phentheanthroline) has been synthesized and structurally determined. The compound 1 crystallizes in the monoclinic system, space group P21/a, with unit cell parameters a = 9.1129(3), b = 24.0033(5), c = 24.4016(6) Å, β = 95.9460(9)°, V = 5308.9(2) Å3, Z = 8, M r = 866.48, D c = 2.168g/cm3, F(000) = 3216, μ(MoKα) = 8.706, and the final R = 0.0373 and wR = 0.0902 for 9408 observed reflections with I ≥ 2σ(I). In 1, the lead centers are in a distorted octahedral environment with stereochemical active 6s2 lone pair, and a one-dimensional chain via edge-sharing of PbI4N2 octahedra can be observed. Furthermore, π···π interaction and hydrogen bonds contribute to the formation of a three-dimensional (3-D) network. The optical band gap of 1 is 2.66 eV, judged from the absorption spectrum. Its fluorescence has also been discussed. Density function theory (DFT) calculation was executed for its electronic structure. [ABSTRACT FROM AUTHOR]