In‐Situ Microfluidic Study of Biphasic Nanocrystal Ligand‐Exchange Reactions Using an Oscillatory Flow Reactor

Shen, Yulong; Abolhasani, Milad; Chen, Yue; Xie, Lisi; Lu, Yang; Coley, Connor W.; Bawendi, Moungi G.; Jensen, Klavs F.

doi:10.1002/anie.201710899

Cited by 37 publications

(32 citation statements)

References 28 publications

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“…Microfluidic reactors allow for the addition of multiple reagents in a user-defined manner, rapid thermal and mass transfer, and quantitative kinetic investigation of reactions, thus defining an ideal medium for preparing semiconductor NCs with well-defined morphologies and physicochemical properties. 100 − 103 In addition, the advances in robust microfluidic configurations, 100 , 103 real-time detection methods, 104 − 111 continuous purification 112 , 113 and ligand-exchange 114 systems, and optimization algorithms 115 − 117 make microfluidic reactors ideal for the detailed investigation of rapid and complex reaction kinetics 77 , 78 , 106 , 118 and for the discovery of multicomponent semiconductor NCs. 77 , 78 , 119 …”

Section: Resultsmentioning

confidence: 99%

Exploration of Near-Infrared-Emissive Colloidal Multinary Lead Halide Perovskite Nanocrystals Using an Automated Microfluidic Platform

et al. 2018

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Hybrid organic–inorganic and fully inorganic lead halide perovskite nanocrystals (NCs) have recently emerged as versatile solution-processable light-emitting and light-harvesting optoelectronic materials. A particularly difficult challenge lies in warranting the practical utility of such semiconductor NCs in the red and infrared spectral regions. In this context, all three archetypal A-site monocationic perovskites—CH3NH3PbI3, CH(NH2)2PbI3, and CsPbI3—suffer from either chemical or thermodynamic instabilities in their bulk form. A promising approach toward the mitigation of these challenges lies in the formation of multinary compositions (mixed cation and mixed anion). In the case of multinary colloidal NCs, such as quinary CsxFA1–xPb(Br1–yIy)3 NCs, the outcome of the synthesis is defined by a complex interplay between the bulk thermodynamics of the solid solutions, crystal surface energies, energetics, dynamics of capping ligands, and the multiple effects of the reagents in solution. Accordingly, the rational synthesis of such NCs is a formidable challenge. Herein, we show that droplet-based microfluidics can successfully tackle this problem and synthesize CsxFA1–xPbI3 and CsxFA1–xPb(Br1–yIy)3 NCs in both a time- and cost-efficient manner. Rapid in situ photoluminescence and absorption measurements allow for thorough parametric screening, thereby permitting precise optical engineering of these NCs. In this showcase study, we fine-tune the photoluminescence maxima of such multinary NCs between 700 and 800 nm, minimize their emission line widths (to below 40 nm), and maximize their photoluminescence quantum efficiencies (up to 89%) and phase/chemical stabilities. Detailed structural analysis revealed that the CsxFA1–xPb(Br1–yIy)3 NCs adopt a cubic perovskite structure of FAPbI3, with iodide anions partially substituted by bromide ions. Most importantly, we demonstrate the excellent transference of reaction parameters from microfluidics to a conventional flask-based environment, thereby enabling up-scaling and further implementation in optoelectronic devices. As an example, CsxFA1–xPb(Br1–yIy)3 NCs with an emission maximum at 735 nm were integrated into light-emitting diodes, exhibiting a high external quantum efficiency of 5.9% and a very narrow electroluminescence spectral bandwidth of 27 nm.

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Section: Resultsmentioning

confidence: 99%

Exploration of Near-Infrared-Emissive Colloidal Multinary Lead Halide Perovskite Nanocrystals Using an Automated Microfluidic Platform

et al. 2018

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“…Furthermore, Hersam et al. demonstrated that the same approach could be expanded to exfoliate bulk BP, another class of layered 2D semiconductors . BP shows a high charge‐carrier mobility but is readily oxidized under ambient conditions, which hinders its practical use.…”

Section: Exfoliation Approachesmentioning

confidence: 99%

Exfoliation of 2D Materials for Energy and Environmental Applications

Kim

et al. 2020

Chemistry A European J

113

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The fascinating properties of single‐layer graphene isolated by mechanical exfoliation have inspired extensive research efforts toward two‐dimensional (2D) materials. Layered compounds serve as precursors for atomically thin 2D materials (briefly, 2D nanomaterials) owing to their strong intraplane chemical bonding but weak interplane van der Waals interactions. There are newly emerging 2D materials beyond graphene, and it is becoming increasingly important to develop cost‐effective, scalable methods for producing 2D nanomaterials with controlled microstructures and properties. The variety of developed synthetic techniques can be categorized into two classes: bottom‐up and top‐down approaches. Of top‐down approaches, the exfoliation of bulk 2D materials into single or few layers is the most common. This review highlights chemical and physical exfoliation methods that allow for the production of 2D nanomaterials in large quantities. In addition, remarkable examples of utilizing exfoliated 2D nanomaterials in energy and environmental applications are introduced.

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“…Until recently, a detailed kinetic understanding of heterogeneous ligand exchange reactions was limited by the labor-intensive phase separation and purification required for offline spectroscopic measurements. Using a single-droplet oscillatory microfluidic reactor with online absorption spectroscopy, Shen and Abolhasani et al [122] studied the biphasic ligand exchange kinetics of oleate (OA)-and octadecylphosphonic acid (ODPA)-capped CdSe QDs (in toluene) with sulfide anions (in formamide), shown in Figure 7C panel I. Because of a difference in the relative velocity of the engulfed polar phase (formamide) and the wetting phase (toluene), the polar phase displaced to the front of the biphasic droplet at the ends of the horseshoe-shaped microfluidic reactor, allowing for straightforward delineation of each phase for online UV-vis absorption analysis.…”

Section: Surface Functionalizationmentioning

confidence: 99%

Accelerated Development of Colloidal Nanomaterials Enabled by Modular Microfluidic Reactors: Toward Autonomous Robotic Experimentation

2020

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Solution-processed organic, [1-3] metallic, [4-6] and semiconductor [7,8] nanomaterials, possess unique size-related physicochemical, optical, magnetic, and electronic properties. These materials have enabled groundbreaking advancements in a variety of applications including catalysis, [9-11] drug delivery, [12,13] data storage, [14] and solar cells. [15] Different nucleation and growth models such as LaMer burst nucleation, [16] Ostwald ripening, [17] Finke-Watzky two-step mechanism, [18] orientated attachment, [19] and coalescence [20] have attempted to explain the mechanisms through which nanoparticles are formed in In recent years, microfluidic technologies have emerged as a powerful approach for the advanced synthesis and rapid optimization of various solution-processed nanomaterials, including semiconductor quantum dots and nanoplatelets, and metal plasmonic and reticular framework nanoparticles. These fluidic systems offer access to previously unattainable measurements and synthesis conditions at unparalleled efficiencies and sampling rates. Despite these advantages, microfluidic systems have yet to be extensively adopted by the colloidal nanomaterial community. To help bridge the gap, this progress report details the basic principles of microfluidic reactor design and performance, as well as the current state of online diagnostics and autonomous robotic experimentation strategies, toward the size, shape, and composition-controlled synthesis of various colloidal nanomaterials. By discussing the application of fluidic platforms in recent high-priority colloidal nanomaterial studies and their potential for integration with rapidly emerging artificial intelligence-based decision-making strategies, this report seeks to encourage interdisciplinary collaborations between microfluidic reactor engineers and colloidal nanomaterial chemists. Full convergence of these two research efforts offers significantly expedited and enhanced nanomaterial discovery, optimization, and manufacturing.

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In‐Situ Microfluidic Study of Biphasic Nanocrystal Ligand‐Exchange Reactions Using an Oscillatory Flow Reactor

Cited by 37 publications

References 28 publications

Exploration of Near-Infrared-Emissive Colloidal Multinary Lead Halide Perovskite Nanocrystals Using an Automated Microfluidic Platform

Exploration of Near-Infrared-Emissive Colloidal Multinary Lead Halide Perovskite Nanocrystals Using an Automated Microfluidic Platform

Exfoliation of 2D Materials for Energy and Environmental Applications

Accelerated Development of Colloidal Nanomaterials Enabled by Modular Microfluidic Reactors: Toward Autonomous Robotic Experimentation

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