10101-63-0Relevant articles and documents
Synthetic Variation and Structural Trends in Layered Two-Dimensional Alkylammonium Lead Halide Perovskites
Paritmongkol, Watcharaphol,Dahod, Nabeel S.,Stollmann, Alexia,Mao, Nannan,Settens, Charles,Zheng, Shao-Liang,Tisdale, William A.
, p. 5592 - 5607 (2019)
We report the cooling-induced crystallization of layered two-dimensional (2D) lead halide perovskites with controllable inorganic quantum-well thicknesses (n = 1, 2, 3, and 4), organic-spacer chain lengths (butyl-, pentyl-, and hexylammonium), A-site cations (methylammonium and formamidinium), and halide anions (iodide and bromide). Using single-crystal X-ray diffraction, we refined crystal structures for the iodide family as a function of these compositional parameters and across their temperature-dependent phase transitions. In general, lower-symmetry crystal structures, increasing extents of organic-spacer interdigitation, and increasing organic-spacer corrugation tilts are observed at low temperature. Moreover, greater structural distortions are observed in lead halide octahedra closest to the organic-spacer layer, and higher-n structures exhibit periodic variation in Pb-I bond lengths. These structural trends are used to explain corresponding temperature-dependent changes in the photoluminescence spectra. We also provide detailed guidance regarding the combination of synthetic parameters needed to achieve phase-pure crystals of each composition and discuss difficulties encountered when trying to synthesize particular members of the 2D perovskite family containing formamidinium or cesium as the A-site cation. These results provide a foundation for understanding structural trends in 2D lead halide perovskites and the effects these trends have on their thermal, electronic, and optical properties.
Controllable perovskite crystallization at a gas-solid interface for hole conductor-free solar cells with steady power conversion efficiency over 10%
Hao, Feng,Stoumpos, Constantinos C.,Liu, Zhao,Chang, Robert P. H.,Kanatzidis, Mercouri G.
, p. 16411 - 16419 (2014)
Depositing a pinhole-free perovskite film is of paramount importance to achieve high performance perovskite solar cells, especially in a heterojunction device format that is free of hole transport material (HTM). Here, we report that high-quality pinhole-free CH3NH3PbI3 perovskite film can be controllably deposited via a facile low-temperature (3NH3PbI3·DMF and CH3NH3PbI3·H2O) have been recognized as the main cause for the incomplete coverage of the resultant film. By avoiding these intermediates, the films crystallized at the gas-solid interface offer several beneficial features for device performance including high surface coverage, small surface roughness, as well as controllable grain size. Highly efficient HTM-free perovskite solar cells were constructed with these pinhole-free CH3NH3PbI3 films, exhibiting significant enhancement of the light harvesting in the long wavelength regime with respect to the conventional solution processed one. Overall, the gas-solid method yields devices with an impressive power conversion efficiency of 10.6% with high reproducibility displaying a negligible deviation of 0.1% for a total of 30 cells.
Chemical and Size Characterization of Layered Lead Iodide Quantum Dots via Optical Spectroscopy and Atomic Force Microscopy
Mu, R.,Tung, Y. S.,Ueda, A.,Henderson, D. O.
, p. 19927 - 19932 (1996)
Lead iodide (PbI2) clusters were synthesized from the chemical reaction of NaI (or KI) with Pb(NO3)2 in H2O, D2O, CH3OH, and C3H7OH solvents.The observation of absorption features between the 550 and 350 nm region obtained with an integrating sphere stron
Crystal structure of the high-temperature polymorph of C(NH2)3PbI3 and its thermal decomposition
Dimitrovska-Lazova, Sandra,Bukleski, Miha,Tzvetkov, Peter,Aleksovska, Slobotka,Kovacheva, Daniela
, (2021)
The synthesis of guanidinium lead iodide, C(NH2)3PbI3 (GUAPbI3), was conducted by slow evaporation of the mixture obtained by dissolving PbI2 and C(NH2)3I in acetonitrile. When the evaporation is done at 40 oC, a yellow needle-like crystals are being formed. The sample was characterized by elemental analysis, density measurements, scanning electron microscopy, thermal analyses, high-temperature X-ray powder diffraction and infrared spectroscopy measurements. The elemental analysis of the obtained crystals confirmed the proposed stoichiometry. The performed thermal analyses showed an endothermic peak associated with structural transition around 160 oC. On the other hand, the endothermic temperature effects above 300 oC are accompanied with mass loss and were interpreted as compound degradation. The crystal structure of high temperature polymorph between 160 oC and 300 oC was determined using high-temperature powder diffraction data measurements at 280 oC using simulated annealing technique in order to obtain initial structural model. The structure was refined using the Rietveld method. At temperatures higher than 160 oC, C(NH2)3PbI3 crystallizes in hexagonal space group P63mc with unit cell parameter a increasing from 9.269 ? to 9.337 ? between 160 oC and 300 oC and c parameter increasing from 15.211 ? to 15.287 ? in the same temperature range. The structure consists of PbI6 octahedra couples sharing a common face, linked with corners. Guanidinium cations are situated in the channels between Pb2I9 couples in a manner that the plane of the molecule is perpendicular to the c-axis.
Spatial-confinement effect on phonons and excitons in PbI2 microcrystallites
Saito, Shingo,Goto, Takenari
, (1995)
We have measured resonant Raman specta and exciton absorption spectra ofPbI2 microcrystallites embedded in ethylene metacrylic acid (E-MAA) cop olymer at 77 and 2 K, respectively. The microcrystallites are platelike and vary in thickness. In the resonant Raman spectra, a new line is observed in the acoustic-phonon energy region, which is intimately related to the excitonabsorption band in the ultrathin microcrystallite with finite number of layers. The phonon energy as a function of the crystal thickness is explained on the basis of a finite chain model. From this analysis, the relationship between the exciton absorption band and the numberof layers is confirmed. Using this relation, we interpret the dependenc e of the exciton energy on the layer thickness, which has been measured previously. Consequently, the thickness dependence of the exciton energyis well explained by the quantum confinement model of the exciton trans lational motion in the crystallites with more than five layers. In crystallites with thinner layers, however, the exciton energies deviate from the theoretical values.
Role of Gravity in the Formation of Liesegang Patterns
Garcia-Ruiz, J. M.,Rondon, D.,Garcia-Romero, A.,Otalora, F.
, p. 8854 - 8860 (1996)
We report the results obtained in four different kinds of experiments designed to test the effect of gravity on the formation of Liesegang patterns.Both reacting solutions (KI and Pb(NO3)2) were gelled with agarose L.The position of the PbI2 precipitates was determined by image analysis, and the kinetic coefficients km = (Xn+1 - Xn)/Xn and kp = (Xn/A)1/n were obtained at different relative orientations of the gravitational field with respect to the direction of the advance of the precipitation front.We conclude that there is not an apparent influence of the gravitational forces on the kinetics of the pattern formation when it is obtained in gelled media at an agarose concentration of 1percent (w/v).When the experiments were performed with agarose at 0.5percent (w/v) or when one of the reacting solutions was ungelled, our tests show clearly the effect of gravity.
Rapid sonochemical preparation of shape-selective lead iodide
Huang, Baojun,He, Qin,Fa, Wenjun,Li, Pinjiang,Zhang, Yange,Zheng, Zhi
, p. 2599 - 2604 (2012)
Lead iodide (PbI2) films/crystals with various nano/micro morphologies (e.g., Nanoflake, block and microrod) were rapidly synthesized by taking advantage of a simple sonochemical method. The PbI2 crystals with uniform nanoflake structures could be fabricated directly on lead foils with the irradiation time as short as 36 s via interfacial reaction between lead foils and elemental iodine in ethanol at ambient temperature. It was found experimentally that the morphologies of the resulting thin films/crystals could be well controlled by the adjustment of several parameters including irradiation time, reaction solvents, iodine concentration, ultrasonic power, and reaction temperature. Most importantly, the resultant PbI2 films are stable enough to resist rolling under the drastic ultrasound irradiation in a liquid media. This method is believed to be the fastest way for in situ fabrication of morphology-controlled semiconductor films on various metal substrates for subsequent applications related to the other metal iodide or metal sulfide semiconductor films.
Dye J-aggregate-semiconductor nanocrystal hybrid nanostructures in reverse micelles: An experimental study
Nikolenko,Brichkin,Razumov
, p. 1196 - 1202 (2011)
Reverse micelle solutions can be used for the assembly of hybrid nanostructures of the composition dye monomer-Ag2S nanocrystal, dye J-aggregate-CuI nanocrystal, and dye J-aggregate-PbI2 nanocrystal. The assembly is effected by means
A novel water-resistant and thermally stable black lead halide perovskite, phenyl viologen lead iodide C22H18N2(PbI3)2
Latini, Alessandro,Quaranta, Simone,Menchini, Francesca,Lisi, Nicola,Di Girolamo, Diego,Tarquini, Ombretta,Colapietro, Marcello,Barba, Luisa,Demitri, Nicola,Cassetta, Alberto
, p. 2616 - 2627 (2020)
A novel black organoammonium iodoplumbate semiconductor, namely phenyl viologen lead iodide C22H18N2(PbI3)2 (PhVPI), was successfully synthesized and characterized. This material showed physical and chemical properties suitable for photovoltaic applications. Indeed, low direct allowed band gap energy (Eg = 1.32 eV) and high thermal stability (up to at least 300 °C) compared to methylammonium lead iodide CH3NH3PbI3 (MAPI, Eg = 1.5 eV) render PhVPI potentially attractive for solar cell fabrication. The compound was extensively characterized by means of X-ray diffraction (performed on both powder and single crystals), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), UV-photoelectron spectroscopy (UPS), FT-IR spectroscopy, TG-DTA, and CHNS analysis. Reactivity towards water was monitored through X-ray powder diffraction carried out after prolonged immersion of the material in water at room temperature. Unlike its methyl ammonium counterpart, PhVPI proved to be unaffected by water exposure. The lack of reactivity towards water is to be attributed to the quaternary nature of the nitrogen atoms of the phenyl viologen units that prevents the formation of acid-base equilibria when in contact with water. On the other hand, PhVPI's thermal stability was evaluated by temperature-controlled powder XRD measurements following an hour-long isothermal treatment at 250 and 300 °C. In both cases no signs of decomposition could be detected. However, the compound melted incongruently at 332 °C producing, upon cooling, a mostly amorphous material. PhVPI was found to be slightly soluble in DMF (～5 mM) and highly soluble in DMSO. Nevertheless, its solubility in DMF can be dramatically increased by adding an equimolar amount of DMSO. Therefore, phenyl viologen lead iodide can be amenable for the fabrication of solar devices by spin coating as actually done for MAPI-based cells. The crystal structure, determined by means of single crystal X-ray diffraction using synchrotron radiation, turned out to be triclinic and consequently differs from the prototypal perovskite structure. In fact, it comprises infinite double chains of corner-sharing PbI6 octahedra along the a-axis direction with phenyl viologen cations positioned between the columns. Finally, the present determination of PhVPI's electronic band structure achieved through UPS and UV-Vis DRS is instrumental in using the material for solar cells.
Predominance of covalency in water-vapor-responsive MMX-type chain complexes revealed by 129I Moessbauer spectroscopy
Iguchi, Hiroaki,Kitao, Shinji,Seto, Makoto,Takaishi, Shinya,Yamashita, Masahiro
, p. 8767 - 8773 (2014)
129I Moessbauer spectroscopy was applied to water-vapor-responsive MMX-type quasi-one-dimensional iodide-bridged Pt complexes (MMX chains) in order to investigate their electronic state quantitatively. Two sets of octuplets observed in K2(H 3NC3H6NH3)[Pt2(pop) 4I]·4H2O (2·4H2O) and one octuplet observed in K2(cis-H3NCH2CHCHCH 2NH3)[Pt2(pop)4I]·4H 2O (1·4H2O) and dehydrated complexes (1 and 2) indicate a unique alternating charge-polarization + charge-density-wave (ACP + CDW) electronic state and a charge-density-wave (CDW) electronic state, respectively. These spectra correspond to their crystal structure and the change of electronic states upon dehydration. Since these complexes consist of an alternating array of positively charged and negatively charged layers, the charge on the iodide ion (ρIS) was discussed on the basis of the isomer shift (IS). The ρIS of the water-vapor-responsive MMX chains was mainly -0.13 to -0.21, which are the smallest of all MMX chains reported so far. Hence, it indicates that the negative charge on the iodide ion is strongly donated to the Pt ion in these complexes. This covalent interaction predominates in the ACP + CDW state as well as in the CDW state. Therefore, the ACP + CDW state is in fact the CDW state with the ACP-type lattice distortion. Because the ρIS became smaller with the decreasing Pt-I-Pt distance, it can be concluded that the covalent interaction plays an important role in determining the electronic states of the MMX chains with pop (= P 2H2O52-) ligands.
