Query: cesium lead mixed halide synthesis by larp

title: Mechanochemical synthesis of 0D and 3D cesium lead mixed halide perovskites.
abstract: A simplified mechanochemical synthesis approach for Cs containing mixed halide perovskite materials of lower and higher dimensionality (0D and 3D, respectively) is presented with stoichiometric control from their halide salts, CsX and PbX2 (X Cl, Br, I) Excellent optical bandgap tunability through halide substitution is supported by property measurements and changes to the materials' structure. Complementary NMR and XRD methods, along with support from DFT calculations, reveal highly crystalline 0D and 3D solid solutions with a complex arrangement of [PbX6 xXx']4 pseudooctahedra caused by halide distribution about the Pb centre.

title: Synthesis of Cesium Lead Halide Perovskite Nanocrystals in a Droplet Based Microfluidic Platform: Fast Parametric Space Mapping.
abstract: Prior to this work, fully inorganic nanocrystals of cesium lead halide perovskite (CsPbX3, X Br, I, Cl and Cl/Br and Br/I mixed halide systems) exhibiting bright and tunable photoluminescence, have been synthesized using conventional batch (flask based) reactions. Unfortunately, our understanding of the parameters governing the formation of these nanocrystals is still very limited due to extremely fast reaction kinetics and multiple variables involved in ion metathesis based synthesis of such multinary halide systems. Herein, we report the use of a droplet based microfluidic platform for the synthesis of CsPbX3 nanocrystals. The combination of online photoluminescence and absorption measurements and the fast mixing of reagents within such a platform allows the rigorous and rapid mapping of the reaction parameters, including molar ratios of Cs, Pb, and halide precursors, reaction temperatures, and reaction times. This translates into enormous savings in reagent usage and screening times when compared to analogous batch synthetic approaches. The early stage insight into the mechanism of nucleation of metal halide nanocrystals suggests similarities with multinary metal chalcogenide systems, albeit with much faster reaction kinetics in the case of halides. Furthermore, we show that microfluidics optimized synthesis parameters are also directly transferrable to the conventional flask based reaction.

title: Generation of cesium lead halide perovskite nanocrystals via a serially integrated microreactor system: Sequential anion exchange reaction
abstract: Inorganic perovskite nanocrystals (NCs) of cesium lead mixed halides (CsPb(X/Y)3, X Br, Y Cl and I) are promising optical materials for developing the high performance photonic devices. Traditionally, anion exchange reaction in perovskite halide NCs provides a simple substitutional way to tune the composition and emitting color with good luminescence properties in the human eye detectable visible spectral regions. However, prior synthetic procedures of perovskite NCs have employed conventional flask based reactions which limit the fine control of perovskite NCs because of extremely fast anion exchange kinetics. To overcome such problems, we demonstrate a droplet based microfluidic system with simple, fast, and high throughput parametric screening for the synthesis of perovskite NCs. By using the customized microfluidic operational system consisting of serially integrated two microfluidic reactors and heating block, we have successfully synthesized CsPbX3 perovskite NCs. In addition, we can finely control the anion exchange reaction which can generate the formation of CsPb(X/Y)3 perovskite NCs with a wide range of visible spectrum (410 630 nm) Ultimately, we have established their potential applications in the development of solid state lighting based flexible display systems.

title: Generalized colloidal synthesis of high quality, two dimensional cesium lead halide perovskite nanosheets and their applications in photodetectors.
abstract: All inorganic cesium lead halide perovskite (CsPbX3, X Cl, Br, and I) nanocrystals (NCs) are emerging as an important class of semiconductor materials with superior photophysical properties and wide potential applications in optoelectronic devices. So far, only a few studies have been conducted to control the shape and geometry of CsPbX3 NCs. Here we report a general approach to directly synthesize two dimensional (2D) CsPbX3 perovskite and mixed perovskite nanosheets with uniform and ultrathin thicknesses down to a few monolayers. The key to the high yield synthesis of perovskite nanosheets is the development of a new Cs oleate precursor. The as synthesized CsPbX3 nanosheets exhibit bright photoluminescence with broad wavelength tunability by composition modulation. The excellent optoelectronic properties of CsPbX3 nanosheets combined with their unique 2D geometry and large lateral dimensions make them ideal building blocks for building functional devices. To demonstrate their potential applications in optoelectronics, photodetectors based on CsPbBr3 nanosheets are fabricated, which exhibit high on/off ratios with a fast response time.

title: Solvent Polarity Engineered Controllable Synthesis of Highly Fluorescent Cesium Lead Halide Perovskite Quantum Dots and Their Use in White Light Emitting Diodes
abstract: Cesium lead halide quantum dots (QDs) have tunable photoluminescence that is capable of covering the entire visible spectrum and have high quantum yields, which make them a new fluorescent materials for various applications. Here, the synthesis of CsPbX3 (X Cl, Br, I, or mixed Cl/Br and Br/I) QDs by direct ion reactions in ether solvents is reported, and for the first time the synergetic effects of solvent polarity and reaction temperature on the nucleation and growth of QDs are demonstrated. The use of solvent with a low polarity enables controlled growth of QDs, which facilitates the synthesis of high quality CsPbX3 QDs with broadly tunable luminescence, narrow emission width, and high quantum yield. A QD white LED (WLED) is demonstrated by coating the highly fluorescent green emissive CsPbBr3 QDs together with red phosphors on a blue InGaN chip, which presents excellent warm white light emission with a high rendering index of 93.2 and color temperature of 5447 K, suggesting the potential applications of highly fluorescent cesium lead halide perovskite QDs as an alternative color converter in the fabrication of WLEDs.

title: Environmentally friendly synthesis of highly luminescent cesium lead halide perovskite nanocrystals using Sn based halide precursors
abstract: In the last several years, cesium lead halide perovskite (CsPbX 3 X Cl, Br, I) nanocrystals (NCs) have attracted much attention as promising kinds of optoelectronic and photonic materials. Via anion exchange reactions, the photoluminescence spectra of the CsPbX 3 NCs can be tuned over nearly the entire visible spectral region. However, the preparation of the anion exchange sources, mainly Pb based halide precursors or oleylammonium halide precursors, would use large amounts of PbX 2 (X Cl, Br, I) trioetylphosphine (TOP) and HX (X Cl, Br, I) These chemicals are toxic and environmentally hazardous. To solve this problem, we report the synthesis of CsPbX 3 (X Cl, Br, I or mixed halides) NCs through modified anion exchange reactions. Using two kinds of Sn based halide precursors as the anion exchange sources, we can finely tune the chemical compositions and optical properties of pre synthesized CsPbX 3 NCs. Considering no PbX 2 TOP and HX have been used in the preparation of the Sn based halide precursors, we can determine this two pot synthetic scheme as a step toward a green chemistry approach for synthesizing high quality CsPbX 3 NCs.

title: Mixed halide CsPb(Br1 xIx)3 nanocrystals for green, orange, and red light emitting diodes
abstract: Cesium lead halide (CsPbX3; X Cl, Br, and I) based nanocrystals (NCs) are an attractive optoelectronic material for next generation lighting and display applications. Except for green emitting CsPbBr3 based NCs, however, there are few investigations for another visible wavelength spectral ranged color emitters, such as yellow, orange, and red light emitting diodes (LEDs) This paper reports a facile synthesis of CsPb(Br1 xIx)3 NCs emitting wavelengths from green to red based on a halide exchange post treatment using a trimethylsilyl iodide (TMSI) additive. Microstructural and optical investigations showed that the TMSI modulated the iodine content of CsPb(Br1 xIx)3 NCs, resulting in a successive shift of photoluminescence peaks from 510 to 663 nm. Based on CsPb(Br1 xIx)3 NCs, LEDs emitting from green to red wavelengths were demonstrated. Interestingly, CsPb(Br1 xIx)3 NCs exhibited abnormal electroluminescence (EL) spectra, showing a large red shift and additional peaks corresponding to the pristine CsPbBr3 NCs. These were attributed to the modification of CsPb(Br1 xIx)3 NCs during the LED fabrication process as well as electrical field induced phase segregation during operation.

title: Controllable Synthesis of All Inorganic Lead Halide Perovskite Nanocrystals with Various Appearances in Multiligand Reaction System
abstract: All inorganic cesium lead halide (CsPbX3, X Cl, Br, I) perovskite nanocrystals (PNCs) exhibit promising applications in light emitting devices due to their excellent photophysical properties. Herein, we developed a low cost and convenient method for the preparation of CsPbX3 PNCs in a multiligand assisted reaction system where peanut oil is applied as a ligand source. The mixed halide PNCs with tunable optical band gap were prepared by mixing the single halide perovskite solutions at room temperature. The resulting PNCs had good monodispersity, with dimensions of 8 10 nm, high photoluminescence quantum yield (96.9% narrow emission widths (15 34 nm) and tunable emission wavelength (408 694 nm) covering the entire visible spectrum. Additionally, various morphologies of PNCs, such as nanospheres, nanocubes, and nanowires, were obtained by controlling reaction temperature and time, and the amount of oleamine with multiple ligands in peanut oil potentially playing a dominant role in the nucleation/growth processes of our PNCs. Finally, the resulting CsPbBr3 PNCs were employed to develop a white light emitting diode (WLED) demonstrating the potential lighting applications for our method.

title: Efficient Thermally Activated Delayed Fluorescence from All Inorganic Cesium Zirconium Halide Perovskite Nanocrystals.
abstract: Thermally activated delayed fluorescence (TADF) is generally observed in solid state organic molecules or metal organic complexes. However, TADF in all inorganic colloidal nanocrystals (NCs) is rare. Herein, we report the first colloidal synthesis of an air stable all inorganic lead free Cs 2 ZrCl 6 perovskite NCs. The Cs 2 ZrCl 6 NCs exhibit long lived triplet excited state (138.2 ms) featuring highly efficient photoluminescence (PL) quantum efficiency (QY= 60.37% due to TADF. The emission color can be easily tuned from blue to green by synthesizing the mixed halide Cs 2 ZrBr x Cl 6 x (0<=x<=1.5) NCs. Both femtosecond transient absorption and temperature dependent PL measurements are performed to clarify the emission mechanism. In addition, Bi 3+ ions are successfully doped into Cs 2 ZrCl 6 NCs, which further extends the PL properties. This work not only develops a new lead free perovskite Cs 2 ZrCl 6 NCs for potential optoelectronic applications, but also offers unique strategies for developing new inorganic phosphors.

title: Colloidal Synthesis and Optical Properties of Perovskite Inspired Cesium Zirconium Halide Nanocrystals
abstract: Optoelectronic devices based on lead halide perovskites are processed in facile ways, yet are remarkably efficient. There are extensive research efforts investigating lead free perovskite and perovskite related compounds, yet there are challenges to synthesize these materials in forms that can be directly integrated into thin film devices rather than as bulk powders. Here, we report on the colloidal synthesis and characterization of lead free, antifluorite Cs2ZrX6 (X Cl, Br) nanocrystals that are readily processed into thin films. We use transmission electron microscopy and powder X ray diffraction measurements to determine their size and structural properties, and solid state nuclear magnetic resonance measurements reveal the presence of oleate ligand, together with a disordered distribution of Cs surface sites. Density functional theory calculations reveal the band structure and fundamental band gaps of 5.06 and 3.91 eV for Cs2ZrCl6 and Cs2ZrBr6, respectively, consistent with experimental values. Finally, we demonstrate that the Cs2ZrCl6 and Cs2ZrBr6 nanocrystal thin films exhibit tunable, broad white photoluminescence with quantum yields of 45% for the latter, with respective peaks in the blue and green spectral regions and mixed systems exhibiting properties between them. Our work represents a critical step toward the application of lead free Cs2ZrX6 nanocrystal thin films into next generation light emitting applications.