- Self-template-directed synthesis of porous perovskite nanowires at room temperature for high-performance visible-light photodetectors
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The unique optoelectronic properties and promising photovoltaic applications of organolead halide perovskites have driven the exploration of facile strategies to synthesize organometal halide perovskites and corresponding hybrid materials and devices. Currently, the preparation of CH3NH3PbBr3 perovskite nanowires, especially those with porous features, is still a great challenge. An efficient self-template-directed synthesis of high-quality porous CH3NH3PbBr3 perovskite nanowires in solution at room temperature using the Pb-containing precursor nanowires as both the sacrificial template and the Pb2+ source in the presence of CH3NH3Br and HBr is now presented. The initial formation of CH3NH3PbBr3 perovskite layers on the surface of the precursor nanowires and the following dissolution of the organic component of the latter led to the formation of mesopores and the preservation of the 1D morphology. Furthermore, the perovskite nanowires are potential materials for visible-light photodetectors with high sensitivity and stability. In solution: Porous CH3NH3PbBr3 perovskite nanowires (PNW-CH3NH3PbBr3) were fabricated by an efficient self-template-directed synthesis using the Pb-containing precursor nanowires as both the sacrificial template and the Pb2+ source in the presence of CH3NH3Br and HBr in solution. The perovskite nanowires are potential materials for visible-light photodetectors.
- Zhuo, Sifei,Zhang, Jingfang,Shi, Yanmei,Huang, Yi,Zhang, Bin
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- Understanding the origin of broad-band emission in CH3NH3PbBr3
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Broad-band emissions related to self-trapped excitons (STEs) in the sub-bandgap region in organic-inorganic hybrid perovskites and double perovskite crystals have drawn attention in recent times due to their potential in optoelectronic device applications. In this study, we have shown that the formation of STEs in CH3NH3PbBr3single crystals can be controlled using a suitable sample synthesis procedure. We have observed a broad-band emission (FWHM ~ 80 nm) for crystals whose crystallization is fast, whereas it was absent if we follow slow crystallization procedures. Using UV-Visible absorption spectroscopy, temperature-dependent photoluminescence (PL), time-resolved PL (TRPL), and dc magnetization studies, we concluded that defect-assisted extrinsic self-trapping is dominant here over the intrinsic self-trapping process and excess Pb atoms in interstitial positions are predominantly responsible for the extrinsic self-trapping process.
- Nandi, Pronoy,Giri, Chandan,Topwal, Dinesh
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- 3D hybrid perovskite solid solutions: a facile approach for deposition of nanoparticles and thin films via B-site substitution
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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.
- Aamir, Muhammad,Mehmood, Rana Farhat,Butt, Arshad Farooq,Khan, Malik Dilshad,Malik, Mohammad Azad,Revaprasadu, Neerish,Nunzi, Jean-Michel,Sher, Muhammad,Akhtar, Javeed
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- Stable fluorescent NH3 sensor based on MAPbBr3 encapsulated by tetrabutylammonium cations
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Recently, organic-inorganic halide perovskite materials were investigated on gas sensing due to their excellent optical properties and gas sensitivities. Here, we designed a stable fluorescent perovskite-based sensor for NH3 detection, in which the CH3NH3PbBr3 (MAPbBr3) film was deposited on the GeO2 substrate and also capped by tetrabutylammonium (TBA) ligand as a stabilizing agent. This as-fabricated MAPbBr3-TBA-based sensor exhibited the relatively strong and stable photoluminescence (PL) intensity, thereby expanding the fluorescence response range for NH3 sensing. Upon exposure to NH3 gas, the PL intensity quenched rapidly by 62.5% with short response time (61 s) and recovery time (65 s). The sensor also possessed a linear relationship between the PL intensity and concentration of NH3 in the range of 0–100 ppm, and presented excellent reversibility, high gas selectivity, and humidity stability. Furthermore, the NH3 sensing mechanism was investigated based on X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Differential thermal analysis-Thermogravimetry (DTA-TG) and fluorescence lifetime measurements, in which the NH3 molecules might permeate the capped TBA ligand and then induce structure transformation of inner MAPbBr3 crystal. This study indicated that the as-prepared MAPbBr3-TBA-based sensor might provide promising applications on NH3 gas detection.
- Cheng, Ya,Chu, Junhao,Jia, Shicheng,Jing, Chengbin,Li, Guishun,Liu, Shaohua,She, Changkun,Yue, Fangyu,Zhang, Wenqian
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- Novel synthesis process of methyl ammonium bromide and effect of particle size on structural, optical and thermodynamic behavior of CH3NH3PbBr3 organometallic perovskite light harvester
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A simple, cost effective production approach having high stability is pertinent to any organic-inorganic perovskite solar cells. The main focus of the present work has been to formulate and estimate the stability of CH3NH3PbBr3 micro-cubes and nanoparticles based perovskite solar cells. Firstly, novel synthesis route has been introduced for the preparation of CH3NH3Br (MABr) electrolyte salt which is less time consuming, as well as cost effective than pristine methods. We also reported a facile single solution process to grow large scale CH3NH3PbBr3 (MAPbBr3) hybrid perovskite micro-cubes and nano-particles. The effect of different size (micro-cube & nano-particles) of perovskite material on structural, optical, thermal stability and degradation kinetics has been examined. X-ray diffraction spectra of MAPbBr3 perovskite reflect high crystallinity and cubic structure of the material at the room temperature. The surface morphology of micro-cubes and nano-particle MAPbBr3 has been obtained from scanning electron microscope (SEM). Broad absorption spectrum has found in the visible region with high absorption coefficient and PL spectra show the green emission which is in good agreement with the optical band gap of MAPbBr3 from absorption measurements. With decreasing the size of perovskite materials, band gap and emission spectra tuned towards the blue region. The simultaneous thermal analysis (STA) study indicates towards the more thermal stability of micro-cubes structures than nanoparticles material while the change in enthalpy (ΔH) and specific heat capacity (ΔCp) of nano particle have increased by reducing the particle size of perovskite due to modification of endothermic peaks.
- Singh, Rajan Kumar,Kumar, Ranveer,Kumar, Amit,Jain, Neha,Singh, Rajiv Kr.,Singh, Jai
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- Single-Source Thermal Ablation of halide perovskites, limitations and opportunities: The lesson of MAPbBr3
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Single-Source Thermal Ablation (SSTA) is a vacuum-based evaporation method that was only minorly employed in the preparation of hybrid perovskite materials for solar cells despite some promising early achievements. We study the preparation of MAPbBr3 films, showing that this material does not allow the reproducible preparation of thin films suitable for integration in multijunction devices due to the low adhesion of MABr to the substrate, on one hand, and to the proximity of decomposition and melting temperatures of MAPbBr3 combined with the high vapor pressure of MABr on the other. Based on the insights obtained on MAPbBr3 processing we demonstrate that, conversely, homogeneous fully-inorganic CsPbI2Br thin films can be prepared by SSTA with a stability comparable to that reported for films obtained by spin coating. This work provides guidelines for the selection of halide perovskites that can be successfully prepared by SSTA for thin film application.
- Calestani, Davide,Ferro, Patrizia,Fracassi, Francesco,Listorti, Andrea,Mezzadri, Francesco,Mosca, Roberto,Nasi, Lucia
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- Self-powered X-ray detector based on methylammonium lead tribromide single crystals
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Low-cost, high sensitivity and self-powered radiation detectors are highly demanded for photon flux detection. Here the fabrication of a self-powered X-ray detector with schottky structure is reported. Organic-inorganic perovskite CH3NH3PbBr3 single crystals have been grown on ITO glass with the solution-processed method at relatively low temperature. Low work function Ag has been deposited on the surface of the crystal to form schottky contact. The devices exhibit an obvious response to both the wavelength of 405 nm laser and X-ray photons without external bias. The achieved X-ray sensitivity is up to 2.35 × 10?4 μC μGy?1cm?2 under 35 kV X-ray exposure without bias. The results demonstrated that this schottky diode based on perovskite enable for energy-saving X-ray detection.
- Xu, Qiang,Zhang, Bohao,Nie, Jing,Zhang, Hang,Ouyang, Xiaoping,Liu, Jun,Liu, Yang
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- Transfer of Chiral Information from Silica Hosts to Achiral Luminescent Guests: a Simple Approach to Accessing Circularly Polarized Luminescent Systems
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Systems that show circularly polarized luminescence (CPL) are usually constructed in one of two possible ways: either covalently binding the chiral moieties (usually organic compounds) to luminophores (inorganic or organic compounds) or associating the luminophores as guests with chiral hosts (usually organic compounds). Herein, we propose inorganic-based CPL-active systems constructed by the “chiral host-luminescent guest” strategy, in which silica acts as a chiral host to endow various luminescent guests with CPL. The chiral silica was modified by silane coupling with amino or phenyl groups to allow interaction with luminescent guests, and then used in combination with acidic achiral dyes, lead-halide type perovskites, and aggregation-induced emission luminogens (AIEgens). Interestingly, when these achiral guests were noncovalently confined in surface-modified chiral silica, the guests showed chiroptical behavior in the circular dichroism (CD) spectra, and thus became CPL active, even though they are not inherently chiral. The surface functional groups on the silica play very important roles in transferring the chiral information from the silica to the guests. This work provides a new concept for constructing CPL-active systems using inorganic materials as a chiral source.
- Tsunega, Seiji,Jin, Ren-Hua,Nakashima, Takuya,Kawai, Tsuyoshi
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- Enhancing performances of hybrid perovskite light emitting diodes with thickness controlled PMMA interlayer
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Solution processed organic-inorganic halide perovskites emerged as efficient materials for the fabrication of lightemitting diodes (LEDs). Spin coating of perovskites on solid support for device integration leads to poor morphology with pinholes and leakage current through electrical shunt paths thereby decreasing the device efficiency. Here, we report a facile route to improve the performance of MAPbBr3 perovskite based LEDs by incorporating a poly(methyl methacrylate) (PMMA) interlayer in the device structure at the interface of ZnO and MAPbBr33layer. The thickness of PMMA interlayer was varied to achieve optimal device performance by overcoming the leakage current and reduced non-radiative recombination pathways. LEDs with optimal PMMA thickness showed a significant enhancement in device performance comparison to the devices without PMMA interlayer. The perovskite LEDs with ~7 nm PMMA interlayer exhibit a maximum luminance of ~3450 cdm-2, current efficiency of ~11.88 cdA-1, external quantum efficiency of ~2.82% and power efficiency of ~4.4 lmW-1 showing robust LED properties with 36-fold enhancement compared to a device without PMMA. Our route provides a convenient way to improve the efficiency of perovskite LEDs by controlling device structure with planar PMMA interlayer, which can be extended to other perovskite LEDs.
- Kumar, Gundam Sandeep,Pradhan, Bapi,Kamilya, Tapas,Acharya, Somobrata
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- Water driven photoluminescence enhancement and recovery of CH3NH3PbBr3/Silicon oil/PDMS-urea composite
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Lead halide perovskites (LHPs) are very promising for new optoelectronic devices due to their excellent optical and electronic properties. However, the poor stability against water, heat and UV light greatly restricts their practical applications. In this work, a CH3NH3PbBr3/silicon oil/PDMS-urea composite is prepared by encapsulating CH3NH3PbBr3 nanocrystals and silicon oil into the PDMS-urea polymer matrix. This composite shows characteristics of water-enhanced photoluminescence (PL) and water-driven PL recovery. After immersed in water, the photoluminescence quantum yield of the composite increases from initial 26.0%–52.2%, which is ascribed to the passivation of surface defects by the capping of polymer chains, H3O+ and OH?. The composite possesses superior stability against UV light illumination in water. Furthermore, the composite film exhibits a capability of water-driven PL recovery after UV light irradiation. By applying alternate water/UV treatments, the PL can be reversibly switched “on and off”. The “on/off” ratio value of the PL intensity reached more than 4. These advantages make this composite highly promising in applications utilising luminescent switching and for under water lighting.
- Huang, Sihui,Jiang, Chunli,Lin, Hechun,Liu, Mengqin,Luo, Chunhua,Peng, Hui,Qi, Ruijuan,Travas-Sejdic, Jadranka,Zhang, Ting
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- Electrochemistry and Electrochemiluminescence of Organometal Halide Perovskite Nanocrystals in Aqueous Medium
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The redox nature and electrochemiluminescence (ECL) of highly crystallized organometal halide perovskite CH3NH3PbBr3 nanocrystals (NCs) in aqueous medium were investigated for the first time. CH3NH3PbBr3 NCs could be electrochemically reduced to negative charge states by injecting electrons into the lowest unoccupied molecular orbitals and oxidized to positive charge states by removing electrons from the highest occupied molecular orbitals; charge transfer between NCs with positive and negative charge states could produce ECL. The redox sequence of CH3NH3PbBr3 NCs played an important role in the generation of charge-transfer-mediated ECL; transient ECL could be achieved only by electrochemically reducing positive-charged NCs in an annihilation route. A large redox current was unfavorable for ECL. Charge mobility within CH3NH3PbBr3 NCs had an important effect on ECL intensity in a co-reactant route, which is promising for photovoltaic and optoelectronic device applications. Importantly, the ECL spectra of CH3NH3PbBr3 NCs were almost identical to their photoluminescence spectra, with a maximum emission around 535 nm and full width at half-maximum around 25 nm; this might open a way to obtaining monochromatic ECL using highly crystallized NCs as emitters, which makes them promising for use in color-selective ECL analysis.
- Tan, Xiao,Zhang, Bin,Zou, Guizheng
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- The Key Role of the Interface in the Highly Sensitive Mechanochromic Luminescence Properties of Hybrid Perovskites
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Hybrid perovskite (HP) materials are of interest in photovoltaics and lighting applications. Here we report that hybrid perovskite composites, as crystallized powders, can behave as intelligent materials showing highly sensitive and reversible mechanochro
- Ben Haj Salah, Maroua,Mercier, Nicolas,Dittmer, Jens,Zouari, Nabil,Botta, Chiara
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- Structural, morphological and thermodynamic parameters investigation of tunable MAPb1?xCdxBr3–2xI2x hybrid perovskite
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Organic-inorganic hybrid perovskites are a leading successor for the next-generation electronic and optoelectronic devices, owing to their unique optical and electrical properties. There has been a concerted effort to understand how different elements can further allow us to tune these properties more favorably for different applications. Herein, we propose to tune these properties further via simultaneous cation-anion co-doping in CH3NH3PbBr3 perovskite using CdI2. We probed how the incorporation of carefully selected anionic and cationic dopants may synergically affect the perovskite properties, including the crystalline phase, thin-film morphology, optical and thermodynamic properties. We supplemented our studies with microscopy, namely SEM coupled with EDAX, to analyze the impact of double dopants on the grain size, pinhole morphology, and elemental composition of the hybrid perovskites. Spectroscopic measurements (UV–Vis–DRS and FTIR) were conducted on the hybrids to see how the interactions with Cd and I with the perovskite might additively modulate the energy band gap and functional group functionality. With the help of the simultaneous application of TGA and DSC, we were able to characterize the thermodynamic behavior (thermal stability and enthalpy change) of co-doped hybrids, which become especially important when operating at scale. This combined spectroscopic and thermodynamic study on the effects of co-doping will help to develop better algorithmic designs to choose multiple dopants which can synergically enhance desired optoelectronic properties at scale.
- Singh, Rajan Kumar,Sharma, Pushkal,Lu, Chung-Hsin,Kumar, Ranveer,Jain, Neha,Singh, Jai
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- Multicolored organic/inorganic hybrid perovskite light-emitting diodes
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(Graph Presented).Bright organic/inorganic hybrid perov-skite light-emitting diodes (PrLEDs) are realized by using CH3NH3PbBr3 as an emitting layer and self-organized buffer hole-injection layer (Buf-HIL). The PrLEDs show high luminance, current efficiency, and EQE of 417 cd m-2, 0.577 cd A-1, and 0.125%, respectively. Buf-HIL can facilitate hole injection into CH3NH3PbBr3 as well as block exciton quenching.
- Kim, Young-Hoon,Cho, Himchan,Heo, Jin Hyuck,Kim, Tae-Sik,Myoung, NoSoung,Lee, Chang-Lyoul,Im, Sang Hyuk,Lee, Tae-Woo
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- Collective and individual impacts of the cascade doping of alkali cations in perovskite single crystals
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Alkali ion (Cs+, Rb+ and K+) incorporated hybrid perovskite polycrystalline films have shown great potential for obtaining highly efficient and stable perovskite solar cells. A study on the intrinsic influence of different alkali ions on perovskites is urgently needed to gain insights into the optoelectronic performance improvement. Single crystals with fewer defects can be ideal candidates for the study of intrinsic properties. Herein, for the first time, we prepared a series of perovskite (FA0.85MA0.15PbI2.55Br0.45) single crystals with Cs+, Rb+, and K+ cascade doping using the inverse temperature crystallization method and systematically characterized their structure and optoelectronic properties, as well as phase, humidity and thermal stability. Our work highlights the structure-property relationship, that is, diversified A-site occupation (especially the FAMACsRb system) can significantly promote the carrier transport behavior of perovskites, as well as achieving better thermal and humidity stability, while K+ doping degrades the intrinsic properties of perovskites, which is probably due to the interstitial occupation of K+. These findings deepen the understanding of the influence of alkali ion doping on the intrinsic properties of perovskite materials, which will provide an exemplary paradigm for further exploration. This journal is
- Huang, Yuan,Si, Rui,Sun, Junliang,Wang, Xiaoge,Zhang, Yu,Zhou, Huanping
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- A Highly Sensitive Single Crystal Perovskite–Graphene Hybrid Vertical Photodetector
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Organolead trihalide perovskites have attracted significant attention for optoelectronic applications due to their excellent physical properties in the past decade. Generally, both grain boundaries in perovskite films and the device structure play key roles in determining the device performance, especially for horizontal-structured device. Here, the first optimized vertical-structured photodetector with the perovskite single crystal MAPbBr3 as the light absorber and graphene as the transport layer is shown. The hybrid device combines strong photoabsorption characteristics of perovskite and high carrier mobility of flexible graphene, exhibits excellent photoresponse performance with high photoresponsivity (≈1017.1 A W?1) and high photodetectivity (≈2.02 × 1013 Jones) in a low light intensity (0.66 mW cm?2) under the actuations of 3 V bias and laser irradiation at 532 nm. In particular, an ultrahigh photoconductive gain of ≈2.37 × 103 is attained because of fast charge transfer in the graphene and large recombination lifetime in the perovskite single crystal. The vertical architecture combining perovskite crystal with highly conductive graphene offers opportunities to fulfill the synergistic effect of perovskite and 2D materials, is thus promising for developing high-performance electronic and optoelectronic devices.
- Zou, Yuting,Zou, Tingting,Zhao, Chen,Wang, Bin,Xing, Jun,Yu, Zhi,Cheng, Jinluo,Xin, Wei,Yang, Jianjun,Yu, Weili,Dong, Huanli,Guo, Chunlei
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- High efficiency and stable photoluminescence of CH3NH3PbBr3@CsPbBr3perovskite quantum dots
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CH3NH3PbBr3@CsPbBr3quantum dots were prepared by epitaxially growing a CsPbBr3shell on the surface of CH3NH3PbBr3due to their similar crystal structures. The inorganic CsPbBr3shell provides enhanced stability for the CH3NH3PbBr3core. Compared with that of CH3NH3PbBr3, the photoluminescence of CH3NH3PbBr3@CsPbBr3quantum dots is not only strong, but also stable for months, in addition to having a high quantum yield.
- Wang, Yajing,Li, Ahui,Hu, Yizhen,Bao, Yanping,Zhang, Yongfan,Hu, Xiaolin,Zhuang, Naifeng
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p. 1356 - 1359
(2021/02/22)
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- Synthesis, crystal chemistry, and optical properties of two methylammonium silver halides: CH3NH3AgBr2and CH3NH3Ag2I3
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Two novel ternary compounds from the pseudobinary CH3NH3X-AgX (X = Br, I) phase diagrams are reported. CH3NH3AgBr2and CH3NH3Ag2I3were synthesizedviasolid state sealed tube reactions and the crystal structures were determined through a combination of single crystal and synchrotron X-ray powder diffraction. Structurally, both compounds consist of one-dimensional ribbons built from silver-centered tetrahedra. The structure of CH3NH3AgBr2possesses orthorhombicPnmasymmetry and is made up of zig-zag chains where each silver bromide tetrahedron shares two edges with neighboring tetrahedra. The tetrahedral coordination of silver is retained in CH3NH3Ag2I3, which has monoclinicP21/msymmetry, but the change in stoichiometry leads to a greater degree of edge-sharing connectivity within the silver iodide chains. With band gaps of 3.3 eV (CH3NH3Ag2I3) and 4.0 eV (CH3NH3AgBr2) the absorption onsets of the ternary phases are significantly blue shifted from the binary silver halides, AgBr and AgI, due in part to the decrease in electronic dimensionality. The compounds are stable for at least one month under ambient conditions and are thermally stable up to approximately 200 °C. Density functional theory calculations reveal very narrow valence bands and moderately disperse conduction bands with Ag 5s character. Bond valence calculations are used to analyze the hydrogen bonding between methylammonium cations and coordinatively unsaturated halide ions. The crystal chemistry of these compounds helps to explain the dearth of iodide double perovskites in the literature.
- Gray, Matthew B.,Harvey, Nicholas P.,Holzapfel, Noah P.,Liu, Tianyu,Woodward, Patrick M.,da Cruz Pinha Barbosa, Victor
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p. 9251 - 9260
(2021/08/05)
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- Thermal and Structural Characterization of Methylammonium- and Formamidinium-Halide Salts
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Four organic halide salts of interest to alloyed perovskite solar cell fabrication are characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (XRD), and thermogravimetric analysis. The chemical and crystal structures of methylammonium iodide (MAI), methylammonium bromide (MABr), and formamidinium iodide (FAI) are confirmed, and the experimental ATR-FTIR spectrum and XRD pattern of formamidinium bromide (FABr) are presented. The enthalpy, ΔH vap, and entropy, ΔS vap, of vaporization are quantified for each salt and are used to estimate their vapor pressures in the temperature range of 150–300 °C. MAI, MABr, and FAI have similar vapor pressures in this temperature range, whereas FABr has a higher vapor pressure in the temperature range of 150–240 °C. These data provide a foundation for achieving effective control of vapor phase concentrations for vapor processing of alloyed perovskite solar cells.
- Harding, Alexander J.,Dobson, Kevin D.,Ogunnaike, Babatunde A.,Shafarman, William N.
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- Structure and Optical Properties of Layered Perovskite (MA)2PbI2-xBrx(SCN)2(0 ≤ x < 1.6)
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The layered perovskite (MA)2PbI2(SCN)2 (MA = CH3NH3+) is a member of an emerging series of compounds derived from hybrid organic-inorganic perovskites. Here, we successfully synthesized (MA)2PbI2-xBrx(SCN)2 (0 ≤ x a solid-state reaction. Despite smaller bromide substitution for iodine, 1% linear expansion along the a axis was observed at x ~0.4 due to a change of the orientation of the SCN- anions. Diffuse reflectance spectra reveal that the optical band gap increases by the bromide substitution, which is supported by the DFT calculations. Curiously, bromine-rich compounds where x ≥ 0.8 are light sensitive, leading to partial decomposition after ~24 h. This study demonstrates that the layered perovskite (MA)2PbI2(SCN)2 tolerates a wide range of bromide substitution toward tuning the band gap energy.
- Yamamoto, Takafumi,Oswald, Iain W. H.,Savory, Christopher N.,Ohmi, Takuya,Koegel, Alexandra A.,Scanlon, David O.,Kageyama, Hiroshi,Neilson, James R.
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p. 17379 - 17384
(2020/12/22)
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- Solvent-free, solid phase synthesis of hybrid lead halide perovskites with superior purity
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A method of synthesizing a mixed-halide perovskite is disclosed herein. The method includes the steps of mixing a first single-halide perovskite and a second single-halide perovskite to form a solid phase mixture and heating the solid phase mixture at a temperature below a first decomposition temperature of the first single-halide perovskite and below a second decomposition temperature of the second single-halide perovskite for a time sufficient to form the mixed-halide perovskite. During the mixing, the first and second single-halide perovskite are both in the solid phase. A mixed-halide perovskite made according to the method is also disclosed herein. The mixed-halide perovskite is free of amorphous and/or semicrystalline phases. The mixed-halide perovskite can be utilized in a photovoltaic cell in a solar panel.
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Page/Page column 6-7
(2020/12/30)
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- Solvent-Free Mechanochemical Synthesis of a Systematic Series of Pure-Phase Mixed-Halide Perovskites MAPb(IxBr1?x)3 and MAPb(BrxCl1?x)3 for Continuous Composition and Band-Gap Tuning
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Hybrid perovskites have recently received much attention in optoelectronic applications. However, hybrid perovskites are unstable in a humid environment. Mixed halide perovskites (MHPs) show enhanced stability and band-gap tunability upon engineering of their halide composition. Here, MHPs are prepared through a solvent-free mechanochemical synthesis (MCS) route that allows superior control over halide compositions than the solvent synthesis routes (SS). The MCS route eliminates the problem in the preparation of MAPb(IxBr1?x)3 with continuously varying x, while maintaining the material properties and suppressing phase segregation present in SS routes. UV-vis absorption and X-ray diffraction patterns confirm the production of the desired pure-phase MHPs. For MAPb(IxBr1?x)3 (0≤x≤1), with increased ratio of halide (x), the cubic phase gradually transforms into the tetragonal phase and band-gap tunability is accomplished. The MCS route for the preparation of MHPs is a very promising and efficient technique for superior control in optoelectronic properties, leading to improved control in fabrication approaches.
- Tang, Sheng,Xiao, Xinyu,Hu, Jing,Gao, Bo,Chen, Hunglin,Peng, Zongyang,Wen, Jianchun,Era, Masanao,Zou, Dechun
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p. 240 - 246
(2020/02/21)
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- Blue-emitting NH4+-doped MAPbBr3perovskite quantum dots with near unity quantum yield and super stability
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Novel NH4+-doped MA1?x(NH4)xPbBr3perovskite quantum dots were synthesized at room temperature. The introduction of NH4+results in larger lattice formation energy and b
- Deng, Jidong,Xun, Jiao,Qin, Youcheng,Li, Ming,He, Rongxing
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supporting information
p. 11863 - 11866
(2020/10/13)
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- Precursor solution volume-dependent ligand-assisted synthesis of CH3NH3PbBr3 perovskite nanocrystals
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Ligand-assisted reprecipitation (LARP) technique is a powerful approach for the synthesis of organometal halide perovskite nanocrystals (PNCs). The morphology and surface property of the formed PNCs which determine their optical properties are ultrasensitive to the synthetic parameters. To guarantee the batch-to-batch reproducibility of PNCs with excellent optical properties, it is of central importance to better understand the factors influencing the formation of PNCs during LARP process. Herein the dual-factor of the amount of perovskite precursor and the polarity of mixture solvent was modified by varying precursor solution volume (PSV) in the LARP system. The concentration, size, surface state and optical properties of the synthesized CH3NH3PbBr3 PNCs as a function of PSV were systematically investigated aiming to understand the influence of the dual-factor on the nucleation and growth of PNCs. Experimental results revealed that few crystal nuclei was generated due to lower amount of precursor at lower PSV, which was favorable for the growth of large perovskite crystals. At the higher PSV, the inhibition of crystal growth with increased amount of precursor was compensated by increasing the polarity of mixture solvent, which led to the dissolution of surface ligands and eventually growth of large perovskite crystals. The obtained results on PSV-dependent synthesis of PNCs will be used as a guide to optimize the synthetic parameters in the LARP process.
- Tang, Yun,Yan, Nan,Wang, Zhiwei,Yuan, Hudie,Xin, Yalou,Yin, Hongfeng
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p. 227 - 233
(2018/10/02)
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- Crystal Growth, Structural Phase Transitions, and Optical Gap Evolution of CH3NH3Pb(Br1-xClx)3 Perovskites
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Chemically tuned inorganic-organic hybrid halide perovskites based on bromide and chloride anions CH3NH3Pb(Br1-xClx)3 have been crystallized and investigated by synchrotron X-ray diffraction (SXRD), scanning electron microscopy, and UV-vis spectroscopy. CH3NH3PbBr3 and CH3NH3PbCl3 experience successive phase transitions upon cooling, which are suppressed for intermediate compositions probably due to compositional disorder. For CH3NH3PbCl3, a transient phase, formerly described as tetragonal, was identified at 167.5 K; the analysis of SXRD data demonstrated that it is indeed orthorhombic, with space group Pnma, and a ≈ 2ap; b ≈ 2ap; c ≈ 2ap (ap is the ideal cubic perovskite unit-cell parameter). The band gap engineering brought about by the chemical management of CH3NH3Pb(Br1-xClx)3 perovskites can be controllably tuned: the gap progressively increases with the concentration of Cl ions from 2.2 to 2.9 eV, and shows a concomitant variation with the unit-cell parameters of the cubic phases at 295 K. This study provides an improved understanding of the structural and optical properties of the mixed CH3NH3Pb(Br1-xClx)3 perovskites.
- Alvarez-Galván,Alonso,López,López-Linares,Contreras,Lázaro,Fauth,Martínez-Huerta
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p. 918 - 924
(2019/01/11)
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- CONTROLLED HOMO-EPITAXIAL GROWTH OF HYBRID PEROVSKITES
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Organic-inorganic hybrid perovskite has demonstrated tremendous potential for the next generation of electronic and optoelectronic devices due to their remarkable carrier dynamics. However, current studies of electronic and optoelectronic devices have been focused on polycrystalline materials, due to the challenges in synthesizing device compatible high quality single crystalline materials. Here, we firstly report the epitaxial growth of single crystal hybrid perovskites with controlled locations, morphologies, and orientations, using combined strategies of lithography, homoepitaxy, and low temperature solution method. The crystals grow following a layer-by-layer model under controlled growth parameters. The process is robust and can be readily scaled up. The as-grown epitaxial single crystals were integrated in an array of light emitting diodes, each crystal as a pixel with enhanced quantum efficiencies. This capability opens up new opportunities for designing and fabricating a diverse range of high performance electronic and optoelectronic devices using crystalline hybrid perovskites.
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Paragraph 00059
(2019/06/09)
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- Controlled synthesis of brightly fluorescent CH3NH3PbBr3 perovskite nanocrystals employing Pb(C17H33COO)2 as the sole lead source
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Organometal halide perovskite nanocrystals hold vast potential for application in photovoltaics, light emitting diodes, low-threshold lasers, and photodetectors due to their size-tunable bandgap energies and photoluminescence as well as excellent electron and hole mobilities. However, the synthesis of such nanocrystals typically suffers from poor structural stability in solution and the coexistence of lamellate nanocrystals (nanoplatelets) and spherical nanocrystals (nanoparticles). Here we show that the pure nanoparticle morphology of CH3NH3PbBr3 nanocrystals can be realized by employing lead oleate (Pb(C17H33COO)2) as the sole lead source and controlled using short- and long-chain mixed alkyl ammonium. These nanocrystals are monodispersed (2.2 ± 0.4 nm in diameter), highly fluorescent (with a quantum yield approaching 85%), and highly stable in the solution (for more than 30 days). Comparative studies reveal that the shape of CH3NH3PbBr3 nanocrystals is strongly dependent on the lead source, PbBr2 and Pb(C17H33COO)2, and evolves as a function of the ratio of short- and long-chain alkyl ammoniums in the precursors. At an optimal short to long-chain alkyl ammonium ratio of 4:6, the growth of CH3NH3PbBr3 nanoplatelets can be selectively suppressed with Pb(C17H33COO)2 as the sole lead source, enhancing the overall photoluminescence quantum yield of the produced CH3NH3PbBr3 nanocrystals. This work reveals important new insights for controlled synthesis of perovskite nanocrystals with pure crystal shape and significantly improved photoluminescence properties and stability.
- Fu, Xiaoming,Peng, Zhiwei,Zhang, Chi,Xia, Yong,Zhang, Jianbing,Luo, Wei,Guo, L. Jay,Li, Honglang,Wang, Yuhuang,Zhang, Daoli
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p. 1132 - 1139
(2018/01/17)
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- Universal Approach toward Hysteresis-Free Perovskite Solar Cell via Defect Engineering
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Organic-inorganic halide perovskite is believed to be a potential candidate for high efficiency solar cells because power conversion efficiency (PCE) was certified to be more than 22%. Nevertheless, mismatch of PCE due to current density (J)-voltage (V) hysteresis in perovskite solar cells is an obstacle to overcome. There has been much lively debate on the origin of J-V hysteresis; however, effective methodology to solve the hysteric problem has not been developed. Here we report a universal approach for hysteresis-free perovskite solar cells via defect engineering. A severe hysteresis observed from the normal mesoscopic structure employing TiO2 and spiro-MeOTAD is almost removed or does not exist upon doping the pure perovskites, CH3NH3PbI3 and HC(NH2)2PbI3, and the mixed cation/anion perovskites, FA0.85MA0.15PbI2.55Br0.45 and FA0.85MA0.1Cs0.05PbI2.7Br0.3, with potassium iodide. Substantial reductions in low-frequency capacitance and bulk trap density are measured from the KI-doped perovskite, which is indicative of trap-hysteresis correlation. A series of experiments with alkali metal iodides of LiI, NaI, KI, RbI and CsI reveals that potassium ion is the right element for hysteresis-free perovskite. Theoretical studies suggest that the atomistic origin of the hysteresis of perovskite solar cells is not the migration of iodide vacancy but results from the formation of iodide Frenkel defect. Potassium ion is able to prevent the formation of Frenkel defect since K+ energetically prefers the interstitial site. A complete removal of hysteresis is more pronounced at mixed perovskite system as compared to pure perovskites, which is explained by lower formation energy of K interstitial (-0.65 V for CH3NH3PbI3 vs -1.17 V for mixed perovskite). The developed KI doping methodology is universally adapted for hysteresis-free perovskite regardless of perovskite composition and device structure.
- Son, Dae-Yong,Kim, Seul-Gi,Seo, Ja-Young,Lee, Seon-Hee,Shin, Hyunjung,Lee, Donghwa,Park, Nam-Gyu
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supporting information
p. 1358 - 1364
(2018/02/09)
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- Surface-enhanced Raman scattering on organic-inorganic hybrid perovskites
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Surface-enhanced Raman scattering (SERS) on organic-inorganic hybrid perovskites is explored and for the first time the SERS activity (EF ≥ 104) of the nanostructured CH3NH3PbBr3 has been proved. Here, the SERS
- Su, Xiaoyue,Ma, Hao,Wang, He,Li, Xueliang,Han, Xiao Xia,Zhao, Bing
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supporting information
p. 2134 - 2137
(2018/03/06)
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- Excellent microwave absorption of lead halide perovskites with high stability
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Given the remarkable progress in physical and structural performances of organic-inorganic lead halide perovskites as a superstar in the photovoltaic field, the study of some of their intrinsic properties is still missing. Herein, we report the microwave absorption performance of MAPbX3 (MA = CH3NH3+, X = I-, Br- or Cl-) perovskite crystals in terms of complex permittivity and permeability. We find that the MAPbI3, MAPbBr3 and MAPbCl3 perovskites possess excellent microwave absorbability, and the optimum reflection losses reach -55.23, -54.70 and -46.44 dB at 16.77, 15.46 and 13.54 GHz with a matching thickness of 1.62, 1.76 and 1.95 mm, respectively. Thereafter, we explore the absorption mechanism and find that the microwave absorption properties can be ascribed to the combination of dielectric loss and magnetic loss, but mainly dielectric loss. In addition, the stability of microwave absorbability is also investigated and it is proved to depend significantly on the decomposition of corresponding perovskites. These results highlight the importance of the discovery of microwave absorbability of organic-inorganic lead halide perovskites. More importantly, our study provides perovskite absorbers as a new variable to be considered in the quest for future microwave devices.
- Guo, Heng,Yang, Jian,Pu, Bingxue,Chen, Haiyuan,Li, Yulan,Wang, Zhiming,Niu, Xiaobin
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p. 4201 - 4207
(2018/04/27)
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- Solvent-Free Solid-State Synthesis of High Yield Mixed Halide Perovskites for Easily Tunable Composition and Band Gap
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We report the preparation of mixed halide hybrid perovskites (CH3NH3PbI3-xBrx) using a solvent-less mechanosynthesis route. Compositional analysis using EDXRF microscopy has confirmed the production of the desir
- Sadhukhan, Priyabrata,Kundu, Samapti,Roy, Atanu,Ray, Apurba,Maji, Prasenjit,Dutta, Hema,Pradhan,Das, Sachindranath
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p. 3428 - 3432
(2018/05/31)
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- Highly stable hole-conductor-free CH3NH3Pb(I1-xBrx)3 perovskite solar cells with carbon counter electrode
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In this work, high stable perovskite solar cells (PSCs) based carbon counter electrode were fabricated in the air environment with 30% of humidity, in which the perovskite CH3NH3Pb(I1-xBrx)3 were used
- Zong, Beibei,Fu, Wuyou,Liu, Huijing,Huang, Liwen,Bala, Hari,Wang, Xiaodong,Sun, Guang,Cao, Jianliang,Zhang, Zhanying
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p. 1006 - 1012
(2018/04/03)
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- PHOTOELECTRIC CONVERSION ELEMENT, SOLAR CELL, AND COMPOUND
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Provided is a photoelectric conversion element including at least a first electrode that includes a conductive support, a photosensitive layer that contains a light absorbing agent, a hole transport layer that contains an organic hole transporting material, and a second electrode. At least one of the photosensitive layer or the hole transport layer is provided on the conductive support to constitute the first electrode in combination with the conductive support. The photosensitive layer includes at least a compound having a perovskite-type crystal structure that includes a cation of an element of Group 1 in the periodic table or a cationic organic group A, a cation of a metal atom M other than elements of Group 1 in the periodic table, and an anion of an anionic atom or atomic group X as the light absorbing agent. The hole transport layer includes at least a compound represented by the following Formula 1 as the organic hole transporting material.
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Paragraph 0664; 0665
(2018/06/04)
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- Method for producing methyl ammonium halide for perovskite solar cell
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The invention relates to a method for producing methyl ammonium halide for a perovskite solar cell. The method is low in cost and comprises the following steps: uniformly mixing ammonium halide powder and solid paraformaldehyde powder according to a molar ratio of 1:(2-2.4), wherein the granularity of the crushed ammonium halide powder and solid paraformaldehyde powder reaches 0.01-0.5 mm; heating to 120-180 DEG C to trigger a 1-6 hours' reaction of the solid powder mixture under the molten condition, and further heating to 190-210 DEG C to continue the reaction till no clear gas is released; and dissolving the produced methyl ammonium halide at 50-70 DEG C by using a C1-C4 aliphatic alcohol and C1-C4 aliphatic ether mixed solvent, slowly cooling the obtained solution to negative 5 DEG C to 5 DEG C, separating out a white methyl ammonium halide crystal, and carrying out vacuum filtering and drying to obtain a high-purity white methyl ammonium halide crystal, wherein the content of high-purity methyl ammonium halide is 99.0-99.5% and the content of impurities is 0.01-0.2%. According to the method provided by the invention, a by-product and an excessive raw material, namely formic acid and formaldehyde, can be subjected to gas-phase volatile separation, and high-purity methyl ammonium halide is easy to obtain.
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Paragraph 0014
(2017/06/08)
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- CH3NH3PbBr3 Perovskite Nanocrystals as Efficient Light-Harvesting Antenna for Fluorescence Resonance Energy Transfer
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Hybrid perovskites have created enormous research interest as a low-cost material for high-performance photovoltaic devices, light-emitting diodes, photodetectors, memory devices and sensors. Perovskite materials in nanocrystal form that display intense luminescence due to the quantum confinement effect were found to be particularly suitable for most of these applications. However, the potential use of perovskite nanocrystals as a light-harvesting antenna for possible applications in artificial photosynthesis systems is not yet explored. In the present work, we study the light-harvesting antenna properties of luminescent methylammonium lead bromide (CH3NH3PbBr3)-based perovskite nanocrystals using fluorescent dyes (rhodamine B, rhodamine 101, and nile red) as energy acceptors. Our studies revealed that CH3NH3PbBr3 nanocrystals are an excellent light-harvesting antenna, and efficient fluorescence resonance energy transfer occurs from the nanocrystals to fluorescent dyes. Further, the energy transfer efficiency is found to be highly dependent on the number of anchoring groups and binding ability of the dyes to the surface of the nanocrystals. These observations may have significant implications for perovskite-based light-harvesting devices and their possible use in artificial photosynthesis systems.
- Muthu, Chinnadurai,Vijayan, Anuja,Nair, Vijayakumar C.
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p. 988 - 995
(2017/05/10)
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- Efficient perovskite solar cells employing a solution-processable copper phthalocyanine as a hole-transporting material
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The development of alternative low-cost and high-performing hole-transporting materials (HTMs) is of great significance for the potential large-scale application of perovskite solar cells (PSCs) in the future. Here, a facilely synthesized solution-processable copper tetra-(2,4-dimethyl-3-pentoxy) phthalocyanine (CuPc-DMP) via only two simple steps, has been incorporated as a hole-transporting material (HTM) in mesoscopic perovskite solar cells (PSCs). The optimized devices based on such a HTM afford a very competitive power conversion efficiency (PCE) of up to 17.1% measured at 100 mW cm–2 AM 1.5G irradiation, which is on par with that of the well-known 2,2′,7,7′-tetrakis(N,N′-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) (16.7%) under equivalent conditions. This is, to the best of our knowledge, the highest value reported so far for metal organic complex-based HTMs in PSCs. The advantages of this HTM observed, such as facile synthetic procedure, superior hole transport characteristic, high photovoltaic performance together with the feasibility of tailoring the molecular structure would make solution-processable copper phthalocyanines as a class of promising HTM that can be further explored in PSCs. The present finding highlights the potential application of solution processed metal organic complexes as HTMs for cost-effective and high-performing PSCs.
- Jiang, Xiaoqing,Yu, Ze,Lai, Jianbo,Zhang, Yuchen,Lei, Ning,Wang, Dongping,Sun, Licheng
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p. 423 - 430
(2017/03/13)
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- Solvent-free, mechanochemical syntheses of bulk trihalide perovskites and their nanoparticles
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For the first time, we have synthesized APbBr3 (A = Cs+/MA+/FA+, where MA+ = CH3NH3+ and FA+ = CH(NH2)2+) bulk as well as nanoparticles (NPs) by solid-state reactions at room temperature. This facile strategy yields different shape structures e.g. square and rectangular (CsPbBr3), spherical (MAPbBr3) and parallelogram (FAPbBr3) NPs.
- Jana, Atanu,Mittal, Mona,Singla, Aayushi,Sapra, Sameer
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supporting information
p. 3046 - 3049
(2017/03/17)
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- Long-distance charge carrier funneling in perovskite nanowires enabled by built-in halide gradient
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The excellent charge carrier transportation in organolead halide perovskites is one major contributor to the high performance of many perovskite-based devices. There still exists a possibility for further enhancement of carrier transportation through nanoscale engineering, owing to the versatile wet-chemistry synthesis and processing of perovskites. Here we report the successful synthesis of bromide-gradient CH3NH3PbBrxI3-x singlecrystalline nanowires (NWs) by a solid-to-solid ion exchange reaction starting from one end of pure CH3NH3PM3 NWs, which was confirmed by local photoluminescence (PL) and energy dispersive X-ray spectroscopy (EDS) measurements. Due to the built-in halide gradient, the long-distance carrier transportation was driven by the energy funnel, rather than the spontaneous carrier diffusion. Indeed, local PL kinetics demonstrated effective charge carrier transportation only from the high-bandgap bromide-rich region to the lowbandgap iodine-rich region over a few micrometers. Therefore, these halide gradient NWs might find applications in various optoelectronic devices requiring long-distance and directional delivery of excitation energy.
- Tian, Wenming,Leng, Jing,Zhao, Chunyi,Jin, Shengye
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supporting information
p. 579 - 582
(2017/05/15)
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- Synthesis, Crystal and Electronic Structures, and Optical Properties of (CH3NH3)2CdX4 (X = Cl, Br, I)
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We report the synthesis, crystal and electronic structures, as well as optical properties of the hybrid organic-inorganic compounds MA2CdX4 (MA = CH3NH3; X = Cl, Br, I). MA2CdI4 is a new compound, whereas, for MA2CdCl4 and MA2CdBr4, structural investigations have already been conducted but electronic structures and optical properties are reported here for the first time. Single crystals were grown through slow evaporation of MA2CdX4 solutions with optimized conditions yielding mm-sized colorless (X = Cl, Br) and pale yellow (X = I) crystals. Single crystal and variable temperature powder X-ray diffraction measurements suggest that MA2CdCl4 forms a 2D layered perovskite structure and has two structural transitions at 283 and 173 K. In contrast, MA2CdBr4 and MA2CdI4 adopt 0D K2SO4-derived crystal structures based on isolated CdX4 tetrahedra and show no phase transitions down to 20 K. The contrasting crystal structures and chemical compositions in the MA2CdX4 family impact their air stabilities, investigated for the first time in this work; MA2CdCl4 is air-stable, whereas MA2CdBr4 and MA2CdI4 partially decompose when left in air. Optical absorption measurements suggest that MA2CdX4 have large optical band gaps above 3.9 eV. Room temperature photoluminescence spectra of MA2CdX4 yield broad peaks in the 375-955 nm range with full width at half-maximum values up to 208 nm. These PL peaks are tentatively assigned to self-trapped excitons in MA2CdX4 following the crystal and electronic structure considerations. The bands around the Fermi level have small dispersions, which is indicative of high charge localization with significant exciton binding energies in MA2CdX4. On the basis of our combined experimental and computational results, MA2CdX4 and related compounds may be of interest for white-light-emitting phosphors and scintillator applications.
- Roccanova, Rachel,Ming, Wenmei,Whiteside, Vincent R.,McGuire, Michael A.,Sellers, Ian R.,Du, Mao-Hua,Saparov, Bayrammurad
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p. 13878 - 13888
(2017/11/24)
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- Stabilization of Organic-Inorganic Perovskite Layers by Partial Substitution of Iodide by Bromide in Methylammonium Lead Iodide
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Thin films of the methylammonium lead halides CH3NH3Pb(I1-xBrx)3 are prepared on fluorine-doped tin oxide substrates and exposed to humid air in the dark and under illumination. To characterize the st
- Ruess, Raffael,Benfer, Felix,B?cher, Felix,Stumpp, Martina,Schlettwein, Derck
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p. 1505 - 1511
(2016/06/01)
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- Mesoscale Growth and Assembly of Bright Luminescent Organolead Halide Perovskite Quantum Wires
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The long carrier lifetimes and low nonradiative recombination rates of organic-inorganic hybrid perovskites have opened new avenues in fabrication of highly efficient solar cells, light-emitting diodes, and lasers. Controlling shapes and organization of newly synthesized perovskite nanostructures should greatly expand their practical application. Here, we report a colloidal synthetic approach to the preparation of methylammonium lead bromide (CH3NH3PbBr3) quantum wires by controlling their surface ligand chemistry to achieve well-defined superstructures. Quantum wire formation was proceeded by the appearance of pearl-necklace assemblies of spherical CH3NH3PbBr3 nanocrystals as intermediates formed mainly through dipolar interactions. The diameter of the quantum wires (~3.8 nm) was found to be larger than the precursor spherical CH3NH3PbBr3 nanocrystals (~2.4 nm). Our experimental findings support mesoscale growth and assembly into CH3NH3PbBr3 quantum wires driven by cooperative interactions between nanocrystals caused by van der Waals interactions and chain interdigitation of surface passivating ligands. The quantum wires displayed an aspect ratio as high as 250 with photoluminescence quantum yield of ~60% and lifetime of ~90 ns, and were aligned in bundles. Our simple colloidal synthetic approach and detailed characterization will inspire rational design of methodologies to prepare diverse anisotropic semiconductor perovskite nanostructures and superstructures, which together will increase the versatility and performance of perovskite materials in optoelectronic and photovoltaic device applications.
- Teunis, Meghan B.,Jana, Atanu,Dutta, Poulami,Johnson, Merrell A.,Mandal, Manik,Muhoberac, Barry B.,Sardar, Rajesh
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p. 5043 - 5054
(2016/08/05)
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- Highly luminescent and stable layered perovskite as the emitter for light emitting diodes
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Air instability and poor exciton recombination of 3D perovskites MAPbX3 (MA = CH3NH3, X = halogens) seriously hinder their applications in light emitting diodes. Herein, we report a promising alternative to solve these two critical drawbacks. Layered perovskite OA2(MA)n?1PbnBr3n+1 (OA = C8H17NH3) has higher binding energy and is passivated by long organic chain, which can be synthesized using a facile method. By increasing the OA+ ratio in layered perovskite, strong quantum confinement effect and obvious features of exciton were observed in photoluminescence and UV-Vis absorption spectra. Notably, the photoluminescence quantum yield (PLQY) of (OA)2(MA)2Pb3Br10 (n = 3 layered perovskite) can be up to 67.3% due to the enhanced exciton recombination, significantly higher than its 3D counterpart. Moreover, layered perovskite exhibits promoted stability in air than that of the 3D perovskite. The layered perovskite (OA)2(MA)2Pb3Br10-based perovskite light emitting diodes (PeLEDs) with a maximum current efficiency, a maximum power efficiency and the external quantum efficiency (EQE) of 1.43 cd A?1, 0.89 lm W?1, and 0.53% was demonstrated, which can be compared with that of the best-reported perovskite quantum dots LEDs so far. The demonstration of layered perovskite renders its bright future in optoelectronic applications, such as displays and photodetections.
- Wei, Mingyang,Sun, Weihai,Liu, Yang,Liu, Zhiwei,Xiao, Lixin,Bian, Zuqiang,Chen, Zhijian
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p. 2727 - 2732
(2016/10/20)
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- 4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions
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Irradiation of N-protected p-hydroxyphenacyl (pHP) ammonium caged derivatives at 313 nm releases primary and secondary amines or ammonia in nearly quantitative yields via the photo-Favorskii reaction when conducted in acidic or neutral aqueous buffered media. The reaction efficiencies are strongly dependent on the pH with the most efficient and highest yields obtained when the pH of the media maintains the ammonium and p-hydroxyl groups as their conjugate acids. For example, the overall quantum yields of simple secondary amines release are 0.5 at acidic pH from 3.9 to 6.6 dropping to 0.1 at neutral pH 7.0 and 0.01 at pH 8.4. Speciation studies provide an acid-base profile that helps define the scope and limitations of the reaction. When the pKa of the ammonium group is lower than that of the phenolic hydroxyl group, as is the case for the α-amino-protected amino acids, the more acidic ammonium ion deprotonates as the media pH is changed from acidic toward neutral or basic, thus diminishing the leaving group ability of the amino group. This, in turn, lowers the propensity for the photo-Favorskii rearrangement reaction to occur and opens the reaction pathway to alternative competing photoreduction process.
- Bownik, Iwona,?ebej, Peter,Literák, Jaromír,Heger, Dominik,?imek, Zdeněk,Givens, Richard S.,Klán, Petr
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p. 9713 - 9721
(2015/10/12)
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- Stable and low-cost mesoscopic CH3NH3PbI2Br perovskite solar cells by using a thin poly(3-hexylthiophene) layer as a hole transporter
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Mesoscopic perovskite solar cells using stable CH3NH3PbI2Br as a light absorber and low-cost poly(3-hexylthiophene) (P3HT) as hole-transporting layer were fabricated, and a power conversion efficiency of 6.64% was achieved. The partial substitution of iodine with bromine in the perovskite led to remarkably prolonged charge carrier lifetime. Meanwhile, the replacement of conventional thick spiro-MeOTAD layer with a thin P3HT layer has significantly reduced the fabrication cost. The solar cells retained their photovoltaic performance well when they were exposed to air without any encapsulation, presenting a favorable stability. The combination of CH3NH3PbI2Br and P3HT may render a practical and cost-effective solid-state photovoltaic system. The superior stability of CH3NH3PbI2Br is also promising for other photoconversion applications.
- Zhang, Meng,Lyu, Miaoqiang,Yu, Hua,Yun, Jung-Ho,Wang, Qiong,Wang, Lianzhou
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p. 434 - 439
(2015/05/19)
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- Visualizing Carrier Diffusion in Individual Single-Crystal Organolead Halide Perovskite Nanowires and Nanoplates
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Single-crystal CH3NH3PbX3 (X = I-, Cl-, Br-) perovskite nanowires (NWs) and nanoplates (NPs), which demonstrate ultracompact sizes and exceptional photophysical properties, offer promises f
- Tian, Wenming,Zhao, Chunyi,Leng, Jing,Cui, Rongrong,Jin, Shengye
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supporting information
p. 12458 - 12461
(2015/10/20)
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- Morphology-Controlled Synthesis of Organometal Halide Perovskite Inverse Opals
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The booming development of organometal halide perovskites in recent years has prompted the exploration of morphology-control strategies to improve their performance in photovoltaic, photonic, and optoelectronic applications. However, the preparation of organometal halide perovskites with high hierarchical architecture is still highly challenging and a general morphology-control method for various organometal halide perovskites has not been achieved. A mild and scalable method to prepare organometal halide perovskites in inverse opal morphology is presented that uses a polystyrene-based artificial opal as hard template. Our method is flexible and compatible with different halides and organic ammonium compositions. Thus, the perovskite inverse opal maintains the advantage of straightforward structure and band gap engineering. Furthermore, optoelectronic investigations reveal that morphology exerted influence on the conducting nature of organometal halide perovskites.
- Chen, Kun,Tüysüz, Harun
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supporting information
p. 13806 - 13810
(2015/11/16)
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- Composition-dependent photoluminescence intensity and prolonged recombination lifetime of perovskite CH3NH3PbBr3-xClx films
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Mixed halide perovskites CH3NH3PbBr3-xClx (x = 0.6-1.2) with different compositions of halogens exhibit drastically changed optical properties. In particular, the thin films prepared with these perovskites demonstrate extraordinary photoluminescence emission intensities and prolonged recombination lifetimes up to 446 ns, which are desirable for light emitting and photovoltaic applications. This journal is
- Zhang, Meng,Yu, Hua,Lyu, Miaoqiang,Wang, Qiong,Yun, Jung-Ho,Wang, Lianzhou
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supporting information
p. 11727 - 11730
(2015/05/20)
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- Ambient pressure aerosol-assisted chemical vapour deposition of (CH 3NH3)PbBr3, an inorganic-organic perovskite important in photovoltaics
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The inorganic-organic perovskite (CH3NH3)PbBr 3, which is potentially important in photovoltaics, has been deposited using aerosol-assisted chemical vapour deposition (AACVD). the Partner Organisations 2014.
- Lewis, David J.,O'Brien, Paul
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supporting information
p. 6319 - 6321
(2014/06/09)
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- Influence of moisture on the preparation, crystal structure, and photophysical properties of organohalide perovskites
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The effect of preparing lead-based organohalide perovskites under inert conditions has been investigated. We find that when prepared under anhydrous conditions, only poorly crystalline powders were obtained. On exposure to small amounts of moisture a rapid crystallization into the expected cubic unit cell for CH3NH3PbBr3 and tetragonal cell for CH3NH3PbI3 is observed. While the as-prepared iodide phase is non-emissive, the lifetime of the emission for the bromide is found to be much longer when prepared under atmospheric conditions.
- Bass, Kelsey K.,McAnally, R. Eric,Zhou, Shiliang,Djurovich, Peter I.,Thompson, Mark E.,Melot, Brent C.
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p. 15819 - 15822
(2015/02/19)
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- EFFECT OF THE STRUCTURE OF AMINES ON RATE AND MECHANISM OF THEIR REACTIONS WITH 2-(β,β-DIBROMOVINYL)-5-NITROFURAN IN ACETONITRILE
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The kinetics of the reaction of 2-(β,β-dibromovinyl)-5-nitrofuran with alkylamines of various types (primary, secondary, and tertiary) in acetonitrile at 55 deg C were studied.It was shown that enamines are formed quantitatively in the case of the reactions with secondary amines.At the same time the products from the reactions with primary amines are the corresponding amidines.Here the monosubstitution product is formed at the first stage, as in the case of the reactions with secondary amines, and rearranges to the imidoyl halide with subsequent substitution of the halogen atom at the imidoyl carbon atom.A quantitative assessment is made of the effect of the structure of the enamine on the rate of the processes.
- Kravchenko, V. V.,Kotenko, A. A.,Popov, A. F.,Kostenko, L. I.,Vegh, D.,Kovac, J.
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p. 2140 - 2143
(2007/10/02)
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