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Seojun Lee, Dong-Won Kang
Compositional engineering of recently-arising methylammonium (MA) lead (Pb) halide based perovskites is an essential approach for finding better perovskite compositions to resolve still remaining issues of toxic Pb, and long-term instability, etc. In this work, we carried out crystallographic, morphological, optical, and photovoltaic characterization of compositional MASn0.6Pb0.4I3-xBrx by gradually introducing bromine (Br) into parental Pb-Sn binary perovskite (MASn0.6Pb0.4I3) to elucidate its function in Sn-rich (Sn : Pb = 6 : 4) perovskites...
June 26, 2017: ACS Applied Materials & Interfaces
Camelia V Stan, Rajkrishna Dutta, Robert J Cava, Vitali B Prakapenka, Thomas S Duffy
The effect of incorporation of Fe(2+) on the perovskite (Pbnm) and postperovskite (Cmcm) structures was investigated in the (Mg,Fe)GeO3 system at high pressures and temperatures using laser-heated diamond anvil cell and synchrotron X-ray diffraction. Samples with compositions of Mg# ≥ 48 were shown to transform to the perovskite (∼30 GPa and ∼1500 K) and postperovskite (>55 GPa, ∼1600-1800 K) structures. Compositions with Mg# ≥ 78 formed single-phase perovskite and postperovskite, whereas those with Mg# < 78 showed evidence for partial decomposition...
June 26, 2017: Inorganic Chemistry
Mohammad Khaja Nazeeruddin, Kasparas Rakstys, Sanghyun Paek, Giulia Grancini, Peng Gao, Vygintas Jankauskas, Abdullah M Asiri
The synthesis, characterization and photovoltaic performance of series of novel molecular hole transporting materials (HTMs) based on bistricyclic aromatic enes (BAEs) are presented. The new derivatives have been obtained following the simple and straightforward two-step procedure from inexpensive starting reagents mimicking the synthetically challenging 9,9'-spirobifluorene moiety of the well-studied spiro-OMeTAD. The novel HTMs are tested in mixed caions and anions perovskite solar cells (PSCs) yielding power conversion efficiency (PCE) of 19...
June 26, 2017: ChemSusChem
Bing Ai, Chao Liu, Zhao Deng, Jing Wang, Jianjun Han, Xiujian Zhao
The photoluminescence properties of perovskite CsPbBr3 QDs embedded in glasses were investigated at cryogenic temperature in the range of 40-240 K. CsPbBr3 QDs with radii of 3.3 nm, 4.2 nm and 4.8 nm were precipitated in phosphate glasses using conventional thermal treatment. Photoluminescence (PL) integral intensities, bandgap energies and full with at half maximum of the PL bands of CsPbBr3 QDs showed a strong dependence on temperature. An exciton binding energy of ∼40 meV was derived from the temperature-dependent emission intensity...
June 26, 2017: Physical Chemistry Chemical Physics: PCCP
Xuan Zheng, Lin Zhou, Ping-Ping Shi, Fu-Juan Geng, Da-Wei Fu, Qiong Ye
A new organic-inorganic perovskite-type compound [(CH3)3PCH2OH][CdBr3] exhibits a ferroelastic phase transition at 339 K. Domain structures were observed and analyzed. The origin of the phase transition can be attributed to the motion or reorientation of the [(CH3)3PCH2OH](+) cations and the displacement of Cd(2+) and Br(-) ions in solid-state crystals.
June 26, 2017: Chemical Communications: Chem Comm
Matthew R Leyden, Lingqiang Meng, Yan Jiang, Luis K Ono, Longbin Qiu, Emilio J Juárez-Pérez, Chuanjiang Qin, Chihaya Adachi, Yabing Qi
Organo-lead-halide perovskites are promising materials for optoelectronic applications. Perovskite solar cells have reached power conversion efficiencies over 22% and perovskite light emitting diodes have recently achieved over 11% external quantum efficiency. To date, most research on perovskite light emitting diodes has focused on solution processed films. There are many advantages of a vapor based growth process to prepare perovskite, including ease of patterning, ability to batch process, and material compatibility...
June 26, 2017: Journal of Physical Chemistry Letters
Yi-Fan Ruan, Nan Zhang, Yuan-Cheng Zhu, Wei-Wei Zhao, Jing-Juan Xu, Hong-Yuan Chen
We have developed sensitive photoelectrochemical (PEC) detection of cysteine using the gold nanoparticles (Au NPs) equipped perovskite Bi4NbO8Cl heterostructure. The Bi4NbO8Cl was prepared by a solid-state reaction, and the Au NPs/Bi4NbO8Cl electrode was made through electrostatic layer-by-layer self-assembly technique. The Au NPs/Bi4NbO8Cl electrode provided much enhanced photocurrent with great increase compared to the bare Bi4NbO8Cl electrode and allow for the plasmon-enhanced PEC detection of cysteine with good performance...
June 26, 2017: Analytical Chemistry
Daniel Errandonea, David Santamaria-Perez, Domingo Martinez-Garcia, Oscar Gomis, Rakesh Shukla, S Nagabhusan Achary, Avesh K Tyagi, Catalin Popescu
The effects of high pressure on the crystal structure of orthorhombic (Pnma) perovskite-type cerium scandate were studied in situ under high pressure by means of synchrotron X-ray powder diffraction, using a diamond-anvil cell. We found that the perovskite-type crystal structure remains stable up to 40 GPa, the highest pressure reached in the experiments. The evolution of unit-cell parameters with pressure indicated an anisotropic compression. The room-temperature pressure-volume equation of state (EOS) obtained from the experiments indicated the EOS parameters V0 = 262...
June 24, 2017: Inorganic Chemistry
Bin Hua, Meng Li, Yi-Fei Sun, Jian-Hui Li, Jing-Li Luo
Perovskite oxides have received a great deal of attentions as promising electrodes in both solid oxide fuel cells (SOFCs) and solid oxide electrolyzer cells (SOECs) because of their reasonable reactivity, impurity tolerance, tunable property, etc. Particular explorations are still required for advancing the perovskite electrodes, which normally suffer from slow kinetics in electrocatalysis. In the past decades, several experimental studies have developed new classes of perovskites with advanced characteristics and electrode kinetics at technical levels...
June 24, 2017: ChemSusChem
Yuhai Zhang, Jun Yin, Manas R Parida, Ghada H Ahmed, Jun Pan, Osman M Bakr, Jean-Luc Bredas, Omar F Mohammed
With record efficiencies achieved in lead halide perovskite-based photovoltaics, urgency has shifted towards finding alternative materials that are stable and less-toxic. Bismuth-based perovskite materials are currently one of the most promising candidates amongst those alternatives. However, the band structures of these materials, including the nature of the bandgaps, remain elusive due to extremely low photoluminescence quantum yield (PLQY) and scattering issues in their thin-film or bulk form. Here, we overcome those limitations and reveal the specific nature of the material's electronic transitions by realizing monodisperse colloidal nanocrystals (NCs) of hexagonal-phase Cs3Bi2X9 perovskites, which afford well-resolved PL features...
June 23, 2017: Journal of Physical Chemistry Letters
James F Scott, Donald M Evans, Ram S Katiyar, Raymond G P McQuaid, J Marty Gregg
Since the 1935 work of Landau-Lifshitz and of Kittel in 1946 all ferromagnetic, ferroelectric, and ferroelastic domains have been thought to be straight-sided with domain widths proportional to the square root of the sample thickness. We show in the present work that this is not true. We also discover period doubling domains predicted by Metaxas et al (2008 Phys. Rev. Lett. 99 217208) and modeled by Wang and Zhao (2015 Sci. Rep. 5 8887). We examine non-equilibrium ferroic domain structures in perovskite oxides with respect to folding, wrinkling, and relaxation and suggest that structures are kinetically limited and in the viscous flow regime predicted by Metaxas et al in 2008 but never observed experimentally...
June 23, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Jiandong Fan, Chong Liu, Hongliang Li, Cuilin Zhang, Wenze Li, Yaohua Mai
The Sn-based perovskite solar cells (PSCs) provide the possibility that swaps the Pb element toward toxic-free PSCs. Here, we innovatively employed a molecular self-assembly approach to obtain a series CH3NH3Pb(1-x)SnxI3 (0≤x≤1) perovskite thin films with full coverage. The optimized planar CH3NH3Pb0.75Sn0.25I3 PSCs with inverted structure was consequently realized with a maximum power conversion efficiency (PCE) over 14 %, which displayed a stabilized power output (SPO) over 12 % within 200 s at 0.6 V forward bias...
June 22, 2017: ChemSusChem
Alberto Fraccarollo, Lorenzo Canti, Leonardo Marchese, Maurizio Cossi
This article describes the structure and the electronic properties of a series of layered perovskites of a general formula (A(+))2(SnX4)(-2) where X = I, Br and A(+) is an organic cation, either formamidinium, 1-methylimidazolium, or phenylethylammonium. For each system, two conformations are considered, with eclipsed or staggered stacking of the adjacent inorganic layers. Geometry optimizations are performed at the density functional theory level with generalized gradient approximation (GGA) functional and semiempirical correction for dispersion energies; band profiles and bandgaps are computed including both spin orbit coupling (SOC) and correlation (GW) effects through an additive scheme...
June 21, 2017: Journal of Chemical Physics
Dominik Kubicki, Daniel Prochowicz, Albert Hofstetter, Peter Pechy, Shaik M Zakeeruddin, Michael Grätzel, Lyndon Emsley
Mixed cation organic lead halide perovskites attract unfaltering attention owing to their excellent photovoltaic properties. Currently, the best performing perovskite materials contains multiple cations and provide power conversion efficiencies up to around 22%. Here, we report the first quantitative, cation-specific data on cation reorientation dynamics in hybrid mixed-cation formamidinium (FA)/methylammonium (MA) lead halide perovskites. We use 14N, 2H, 13C and 1H solid-state MAS NMR to elucidate cation reorientation dynamics, microscopic phase composition, and the MA/FA ratio, in (MA)x(FA)1-xPbI3 between 100 and 330 K...
June 23, 2017: Journal of the American Chemical Society
Kwing To Lai, Iryna Antonyshyn, Yurii Prots, Martin Valldor
Through single-step solid-state reactions, a series of novel bichalcogenides with the general composition (Li2Fe)ChO (Ch = S, Se, Te) are successfully synthesized. (Li2Fe)ChO (Ch = S, Se) possess cubic anti-perovskite crystal structures, where Fe and Li are completely disordered on a common crystallographic site (3c). According to Goldschmidt calculations, Li(+) and Fe(2+) are too small for their common atomic position and exhibit large thermal displacements in the crys-tal structure models, implying high cation mobility...
June 23, 2017: Journal of the American Chemical Society
Yunlong Guo, Wataru Sato, Kazutaka Shoyama, Henry Halim, Yuki Itabashi, Rui Shang, Eiichi Nakamura
Solar cells made of lead perovskite crystals have attracted much attention for their high performance, but far less attention as a subject of crystal engineering. Here, we report that citric acid (CA) and chloride anion, working together modulate crystal growth of CH3NH3PbI3, producing sub-mm-sized cuboid crystals-a morphology more suitable for close packing in a thin film than the commonly observed elongated dodecahedral morphology. By using a 15-wt% CA-doped precursor solution, we formed a single layer of large, flat and oriented cuboid crystals with minimum crystal domain boundaries and maximum contact with neighboring layers, and fabricated an archetypal inverted-structured device of 4-mm2 area, which showed, reproducibly and with little hysteresis, 16...
June 23, 2017: Journal of the American Chemical Society
Wolfgang Tress
Metal halide perovskites are promising candidates for many classes of different optoelectronic devices. Apart from being a semiconductor, they additionally show ionic conductivity. It expresses itself in slow response times, reversible degradation, and hysteresis in the current-voltage characteristics of solar cells. This Perspective gives a condensed overview about experiments and theory on ion migration in metal halide perovskites focusing on its effects in solar cells. Apart from being a potential stability concern for photovoltaics, ion migration paired with the excellent optoelectronic properties of this material offers opportunities for novel devices such as optically controlled memristors and switchable diodes...
June 22, 2017: Journal of Physical Chemistry Letters
Yan Li, Jinguang Cheng, José Antonio Alonso, John B Goodenough, Jianshi Zhou
A SrRhO3 polytype with six-layered (6M) structure was synthesized under high pressure and high temperature. The crystal structure was obtained by refining X-ray powder diffraction with the monoclinic space group C2/c with lattice parameters a = 5.5650(1) Å, b = 9.5967(2) Å, c = 14.0224(4) Å, and β = 92.846(2)°. It is isostructural with SrIrO3 synthesized under ambient pressure and consists of dimers of the face-shared Rh(2)O6 octahedra connected by their vertices to the corner-shared Rh(1)O6 octahedra along the c axis with a stacking of SrO3 layers in the sequence of CCHCCH, where C and H denote cubic and hexagonal closed packing, respectively...
June 22, 2017: Inorganic Chemistry
Jung-Yao Chen, Yu-Cheng Chiu, Yen-Ting Li, Chu-Chen Chueh, Wen-Chang Chen
Solution-processable organic-inorganic hybrid perovskite materials with a wealth of exotic semiconducting properties have appeared as the promising front-runners for next-generation electronic devices. Further, regarding its well photoresponsibility, various perovskite-based photosensing devices are prosperously developed in recent years. However, most exploited devices to date only transiently transduce the optical signals into electrical circuits while under illumination, which necessitates using additional converters to further store the output signals for recording the occurrence of light stimulation...
June 22, 2017: Advanced Materials
Manukumara Manjappa, Yogesh Kumar Srivastava, Ankur Solanki, Abhishek Kumar, Tze Chien Sum, Ranjan Singh
The recent meteoric rise in the field of photovoltaics with the discovery of highly efficient solar-cell devices is inspired by solution-processed organic-inorganic lead halide perovskites that exhibit unprecedented light-to-electricity conversion efficiencies. The stunning performance of perovskites is attributed to their strong photoresponsive properties that are thoroughly utilized in designing excellent perovskite solar cells, light-emitting diodes, infrared lasers, and ultrafast photodetectors. However, optoelectronic application of halide perovskites in realizing highly efficient subwavelength photonic devices has remained a challenge...
June 22, 2017: Advanced Materials
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